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![Joe Lawrence](/assets/img/avatar_default.png)
Tidy up and use cond_resched_rcu_qs when calling cond_resched and reporting potential quiescent state to RCU. Splitting this change in this way allows easy backporting to -stable for kernel versions not having cond_resched_rcu_qs(). Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
4903 lines
136 KiB
C
4903 lines
136 KiB
C
/*
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* kernel/workqueue.c - generic async execution with shared worker pool
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*
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* Copyright (C) 2002 Ingo Molnar
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*
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* Derived from the taskqueue/keventd code by:
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* David Woodhouse <dwmw2@infradead.org>
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* Andrew Morton
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* Kai Petzke <wpp@marie.physik.tu-berlin.de>
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* Theodore Ts'o <tytso@mit.edu>
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*
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* Made to use alloc_percpu by Christoph Lameter.
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*
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* Copyright (C) 2010 SUSE Linux Products GmbH
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* Copyright (C) 2010 Tejun Heo <tj@kernel.org>
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*
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* This is the generic async execution mechanism. Work items as are
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* executed in process context. The worker pool is shared and
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* automatically managed. There are two worker pools for each CPU (one for
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* normal work items and the other for high priority ones) and some extra
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* pools for workqueues which are not bound to any specific CPU - the
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* number of these backing pools is dynamic.
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*
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* Please read Documentation/workqueue.txt for details.
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*/
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#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/init.h>
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#include <linux/signal.h>
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#include <linux/completion.h>
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#include <linux/workqueue.h>
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#include <linux/slab.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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#include <linux/kthread.h>
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#include <linux/hardirq.h>
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#include <linux/mempolicy.h>
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#include <linux/freezer.h>
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#include <linux/kallsyms.h>
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#include <linux/debug_locks.h>
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#include <linux/lockdep.h>
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#include <linux/idr.h>
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#include <linux/jhash.h>
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#include <linux/hashtable.h>
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#include <linux/rculist.h>
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#include <linux/nodemask.h>
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#include <linux/moduleparam.h>
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#include <linux/uaccess.h>
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#include "workqueue_internal.h"
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enum {
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/*
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* worker_pool flags
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*
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* A bound pool is either associated or disassociated with its CPU.
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* While associated (!DISASSOCIATED), all workers are bound to the
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* CPU and none has %WORKER_UNBOUND set and concurrency management
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* is in effect.
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*
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* While DISASSOCIATED, the cpu may be offline and all workers have
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* %WORKER_UNBOUND set and concurrency management disabled, and may
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* be executing on any CPU. The pool behaves as an unbound one.
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*
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* Note that DISASSOCIATED should be flipped only while holding
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* attach_mutex to avoid changing binding state while
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* worker_attach_to_pool() is in progress.
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*/
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POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
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/* worker flags */
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WORKER_DIE = 1 << 1, /* die die die */
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WORKER_IDLE = 1 << 2, /* is idle */
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WORKER_PREP = 1 << 3, /* preparing to run works */
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WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
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WORKER_UNBOUND = 1 << 7, /* worker is unbound */
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WORKER_REBOUND = 1 << 8, /* worker was rebound */
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WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE |
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WORKER_UNBOUND | WORKER_REBOUND,
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NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */
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UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */
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BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
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MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
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IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
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MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2,
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/* call for help after 10ms
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(min two ticks) */
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MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
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CREATE_COOLDOWN = HZ, /* time to breath after fail */
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/*
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* Rescue workers are used only on emergencies and shared by
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* all cpus. Give MIN_NICE.
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*/
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RESCUER_NICE_LEVEL = MIN_NICE,
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HIGHPRI_NICE_LEVEL = MIN_NICE,
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WQ_NAME_LEN = 24,
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};
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/*
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* Structure fields follow one of the following exclusion rules.
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*
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* I: Modifiable by initialization/destruction paths and read-only for
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* everyone else.
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*
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* P: Preemption protected. Disabling preemption is enough and should
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* only be modified and accessed from the local cpu.
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*
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* L: pool->lock protected. Access with pool->lock held.
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*
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* X: During normal operation, modification requires pool->lock and should
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* be done only from local cpu. Either disabling preemption on local
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* cpu or grabbing pool->lock is enough for read access. If
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* POOL_DISASSOCIATED is set, it's identical to L.
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*
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* A: pool->attach_mutex protected.
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*
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* PL: wq_pool_mutex protected.
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*
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* PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads.
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*
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* WQ: wq->mutex protected.
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*
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* WR: wq->mutex protected for writes. Sched-RCU protected for reads.
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*
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* MD: wq_mayday_lock protected.
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*/
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/* struct worker is defined in workqueue_internal.h */
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struct worker_pool {
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spinlock_t lock; /* the pool lock */
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int cpu; /* I: the associated cpu */
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int node; /* I: the associated node ID */
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int id; /* I: pool ID */
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unsigned int flags; /* X: flags */
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struct list_head worklist; /* L: list of pending works */
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int nr_workers; /* L: total number of workers */
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/* nr_idle includes the ones off idle_list for rebinding */
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int nr_idle; /* L: currently idle ones */
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struct list_head idle_list; /* X: list of idle workers */
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struct timer_list idle_timer; /* L: worker idle timeout */
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struct timer_list mayday_timer; /* L: SOS timer for workers */
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/* a workers is either on busy_hash or idle_list, or the manager */
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DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
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/* L: hash of busy workers */
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/* see manage_workers() for details on the two manager mutexes */
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struct mutex manager_arb; /* manager arbitration */
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struct mutex attach_mutex; /* attach/detach exclusion */
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struct list_head workers; /* A: attached workers */
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struct completion *detach_completion; /* all workers detached */
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struct ida worker_ida; /* worker IDs for task name */
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struct workqueue_attrs *attrs; /* I: worker attributes */
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struct hlist_node hash_node; /* PL: unbound_pool_hash node */
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int refcnt; /* PL: refcnt for unbound pools */
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/*
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* The current concurrency level. As it's likely to be accessed
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* from other CPUs during try_to_wake_up(), put it in a separate
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* cacheline.
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*/
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atomic_t nr_running ____cacheline_aligned_in_smp;
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/*
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* Destruction of pool is sched-RCU protected to allow dereferences
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* from get_work_pool().
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*/
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struct rcu_head rcu;
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} ____cacheline_aligned_in_smp;
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/*
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* The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS
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* of work_struct->data are used for flags and the remaining high bits
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* point to the pwq; thus, pwqs need to be aligned at two's power of the
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* number of flag bits.
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*/
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struct pool_workqueue {
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struct worker_pool *pool; /* I: the associated pool */
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struct workqueue_struct *wq; /* I: the owning workqueue */
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int work_color; /* L: current color */
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int flush_color; /* L: flushing color */
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int refcnt; /* L: reference count */
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int nr_in_flight[WORK_NR_COLORS];
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/* L: nr of in_flight works */
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int nr_active; /* L: nr of active works */
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int max_active; /* L: max active works */
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struct list_head delayed_works; /* L: delayed works */
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struct list_head pwqs_node; /* WR: node on wq->pwqs */
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struct list_head mayday_node; /* MD: node on wq->maydays */
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/*
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* Release of unbound pwq is punted to system_wq. See put_pwq()
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* and pwq_unbound_release_workfn() for details. pool_workqueue
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* itself is also sched-RCU protected so that the first pwq can be
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* determined without grabbing wq->mutex.
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*/
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struct work_struct unbound_release_work;
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struct rcu_head rcu;
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} __aligned(1 << WORK_STRUCT_FLAG_BITS);
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/*
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* Structure used to wait for workqueue flush.
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*/
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struct wq_flusher {
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struct list_head list; /* WQ: list of flushers */
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int flush_color; /* WQ: flush color waiting for */
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struct completion done; /* flush completion */
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};
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struct wq_device;
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/*
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* The externally visible workqueue. It relays the issued work items to
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* the appropriate worker_pool through its pool_workqueues.
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*/
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struct workqueue_struct {
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struct list_head pwqs; /* WR: all pwqs of this wq */
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struct list_head list; /* PL: list of all workqueues */
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struct mutex mutex; /* protects this wq */
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int work_color; /* WQ: current work color */
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int flush_color; /* WQ: current flush color */
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atomic_t nr_pwqs_to_flush; /* flush in progress */
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struct wq_flusher *first_flusher; /* WQ: first flusher */
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struct list_head flusher_queue; /* WQ: flush waiters */
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struct list_head flusher_overflow; /* WQ: flush overflow list */
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struct list_head maydays; /* MD: pwqs requesting rescue */
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struct worker *rescuer; /* I: rescue worker */
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int nr_drainers; /* WQ: drain in progress */
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int saved_max_active; /* WQ: saved pwq max_active */
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struct workqueue_attrs *unbound_attrs; /* WQ: only for unbound wqs */
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struct pool_workqueue *dfl_pwq; /* WQ: only for unbound wqs */
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#ifdef CONFIG_SYSFS
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struct wq_device *wq_dev; /* I: for sysfs interface */
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#endif
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#ifdef CONFIG_LOCKDEP
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struct lockdep_map lockdep_map;
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#endif
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char name[WQ_NAME_LEN]; /* I: workqueue name */
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/* hot fields used during command issue, aligned to cacheline */
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unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */
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struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */
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struct pool_workqueue __rcu *numa_pwq_tbl[]; /* FR: unbound pwqs indexed by node */
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};
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static struct kmem_cache *pwq_cache;
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static cpumask_var_t *wq_numa_possible_cpumask;
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/* possible CPUs of each node */
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static bool wq_disable_numa;
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module_param_named(disable_numa, wq_disable_numa, bool, 0444);
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/* see the comment above the definition of WQ_POWER_EFFICIENT */
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#ifdef CONFIG_WQ_POWER_EFFICIENT_DEFAULT
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static bool wq_power_efficient = true;
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#else
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static bool wq_power_efficient;
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#endif
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module_param_named(power_efficient, wq_power_efficient, bool, 0444);
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static bool wq_numa_enabled; /* unbound NUMA affinity enabled */
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/* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
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static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf;
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static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */
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static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
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static LIST_HEAD(workqueues); /* PL: list of all workqueues */
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static bool workqueue_freezing; /* PL: have wqs started freezing? */
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/* the per-cpu worker pools */
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static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS],
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cpu_worker_pools);
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static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */
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/* PL: hash of all unbound pools keyed by pool->attrs */
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static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER);
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/* I: attributes used when instantiating standard unbound pools on demand */
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static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS];
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/* I: attributes used when instantiating ordered pools on demand */
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static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS];
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struct workqueue_struct *system_wq __read_mostly;
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EXPORT_SYMBOL(system_wq);
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struct workqueue_struct *system_highpri_wq __read_mostly;
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EXPORT_SYMBOL_GPL(system_highpri_wq);
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struct workqueue_struct *system_long_wq __read_mostly;
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EXPORT_SYMBOL_GPL(system_long_wq);
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struct workqueue_struct *system_unbound_wq __read_mostly;
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EXPORT_SYMBOL_GPL(system_unbound_wq);
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struct workqueue_struct *system_freezable_wq __read_mostly;
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EXPORT_SYMBOL_GPL(system_freezable_wq);
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struct workqueue_struct *system_power_efficient_wq __read_mostly;
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EXPORT_SYMBOL_GPL(system_power_efficient_wq);
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struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly;
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EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq);
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static int worker_thread(void *__worker);
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static void copy_workqueue_attrs(struct workqueue_attrs *to,
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const struct workqueue_attrs *from);
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#define CREATE_TRACE_POINTS
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#include <trace/events/workqueue.h>
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#define assert_rcu_or_pool_mutex() \
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rcu_lockdep_assert(rcu_read_lock_sched_held() || \
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lockdep_is_held(&wq_pool_mutex), \
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"sched RCU or wq_pool_mutex should be held")
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#define assert_rcu_or_wq_mutex(wq) \
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rcu_lockdep_assert(rcu_read_lock_sched_held() || \
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lockdep_is_held(&wq->mutex), \
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"sched RCU or wq->mutex should be held")
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#define for_each_cpu_worker_pool(pool, cpu) \
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for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
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(pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
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(pool)++)
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/**
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* for_each_pool - iterate through all worker_pools in the system
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* @pool: iteration cursor
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* @pi: integer used for iteration
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*
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* This must be called either with wq_pool_mutex held or sched RCU read
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* locked. If the pool needs to be used beyond the locking in effect, the
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* caller is responsible for guaranteeing that the pool stays online.
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*
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* The if/else clause exists only for the lockdep assertion and can be
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* ignored.
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*/
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#define for_each_pool(pool, pi) \
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idr_for_each_entry(&worker_pool_idr, pool, pi) \
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if (({ assert_rcu_or_pool_mutex(); false; })) { } \
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else
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/**
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* for_each_pool_worker - iterate through all workers of a worker_pool
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* @worker: iteration cursor
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* @pool: worker_pool to iterate workers of
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*
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* This must be called with @pool->attach_mutex.
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*
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* The if/else clause exists only for the lockdep assertion and can be
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* ignored.
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*/
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#define for_each_pool_worker(worker, pool) \
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list_for_each_entry((worker), &(pool)->workers, node) \
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if (({ lockdep_assert_held(&pool->attach_mutex); false; })) { } \
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else
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/**
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* for_each_pwq - iterate through all pool_workqueues of the specified workqueue
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* @pwq: iteration cursor
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* @wq: the target workqueue
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*
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* This must be called either with wq->mutex held or sched RCU read locked.
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* If the pwq needs to be used beyond the locking in effect, the caller is
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* responsible for guaranteeing that the pwq stays online.
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*
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* The if/else clause exists only for the lockdep assertion and can be
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* ignored.
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*/
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#define for_each_pwq(pwq, wq) \
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list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \
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if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \
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else
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#ifdef CONFIG_DEBUG_OBJECTS_WORK
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static struct debug_obj_descr work_debug_descr;
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static void *work_debug_hint(void *addr)
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{
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return ((struct work_struct *) addr)->func;
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}
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/*
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* fixup_init is called when:
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* - an active object is initialized
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*/
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static int work_fixup_init(void *addr, enum debug_obj_state state)
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{
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struct work_struct *work = addr;
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switch (state) {
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case ODEBUG_STATE_ACTIVE:
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cancel_work_sync(work);
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debug_object_init(work, &work_debug_descr);
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return 1;
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default:
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return 0;
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}
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}
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/*
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* fixup_activate is called when:
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* - an active object is activated
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* - an unknown object is activated (might be a statically initialized object)
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*/
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static int work_fixup_activate(void *addr, enum debug_obj_state state)
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{
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struct work_struct *work = addr;
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switch (state) {
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case ODEBUG_STATE_NOTAVAILABLE:
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/*
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* This is not really a fixup. The work struct was
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* statically initialized. We just make sure that it
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* is tracked in the object tracker.
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*/
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if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
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debug_object_init(work, &work_debug_descr);
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debug_object_activate(work, &work_debug_descr);
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return 0;
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}
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WARN_ON_ONCE(1);
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return 0;
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case ODEBUG_STATE_ACTIVE:
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WARN_ON(1);
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default:
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return 0;
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}
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}
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/*
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* fixup_free is called when:
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* - an active object is freed
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*/
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static int work_fixup_free(void *addr, enum debug_obj_state state)
|
|
{
|
|
struct work_struct *work = addr;
|
|
|
|
switch (state) {
|
|
case ODEBUG_STATE_ACTIVE:
|
|
cancel_work_sync(work);
|
|
debug_object_free(work, &work_debug_descr);
|
|
return 1;
|
|
default:
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
static struct debug_obj_descr work_debug_descr = {
|
|
.name = "work_struct",
|
|
.debug_hint = work_debug_hint,
|
|
.fixup_init = work_fixup_init,
|
|
.fixup_activate = work_fixup_activate,
|
|
.fixup_free = work_fixup_free,
|
|
};
|
|
|
|
static inline void debug_work_activate(struct work_struct *work)
|
|
{
|
|
debug_object_activate(work, &work_debug_descr);
|
|
}
|
|
|
|
static inline void debug_work_deactivate(struct work_struct *work)
|
|
{
|
|
debug_object_deactivate(work, &work_debug_descr);
|
|
}
|
|
|
|
void __init_work(struct work_struct *work, int onstack)
|
|
{
|
|
if (onstack)
|
|
debug_object_init_on_stack(work, &work_debug_descr);
|
|
else
|
|
debug_object_init(work, &work_debug_descr);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__init_work);
|
|
|
|
void destroy_work_on_stack(struct work_struct *work)
|
|
{
|
|
debug_object_free(work, &work_debug_descr);
|
|
}
|
|
EXPORT_SYMBOL_GPL(destroy_work_on_stack);
|
|
|
|
void destroy_delayed_work_on_stack(struct delayed_work *work)
|
|
{
|
|
destroy_timer_on_stack(&work->timer);
|
|
debug_object_free(&work->work, &work_debug_descr);
|
|
}
|
|
EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack);
|
|
|
|
#else
|
|
static inline void debug_work_activate(struct work_struct *work) { }
|
|
static inline void debug_work_deactivate(struct work_struct *work) { }
|
|
#endif
|
|
|
|
/**
|
|
* worker_pool_assign_id - allocate ID and assing it to @pool
|
|
* @pool: the pool pointer of interest
|
|
*
|
|
* Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned
|
|
* successfully, -errno on failure.
|
|
*/
|
|
static int worker_pool_assign_id(struct worker_pool *pool)
|
|
{
|
|
int ret;
|
|
|
|
lockdep_assert_held(&wq_pool_mutex);
|
|
|
|
ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE,
|
|
GFP_KERNEL);
|
|
if (ret >= 0) {
|
|
pool->id = ret;
|
|
return 0;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* unbound_pwq_by_node - return the unbound pool_workqueue for the given node
|
|
* @wq: the target workqueue
|
|
* @node: the node ID
|
|
*
|
|
* This must be called either with pwq_lock held or sched RCU read locked.
|
|
* If the pwq needs to be used beyond the locking in effect, the caller is
|
|
* responsible for guaranteeing that the pwq stays online.
|
|
*
|
|
* Return: The unbound pool_workqueue for @node.
|
|
*/
|
|
static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq,
|
|
int node)
|
|
{
|
|
assert_rcu_or_wq_mutex(wq);
|
|
return rcu_dereference_raw(wq->numa_pwq_tbl[node]);
|
|
}
|
|
|
|
static unsigned int work_color_to_flags(int color)
|
|
{
|
|
return color << WORK_STRUCT_COLOR_SHIFT;
|
|
}
|
|
|
|
static int get_work_color(struct work_struct *work)
|
|
{
|
|
return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
|
|
((1 << WORK_STRUCT_COLOR_BITS) - 1);
|
|
}
|
|
|
|
static int work_next_color(int color)
|
|
{
|
|
return (color + 1) % WORK_NR_COLORS;
|
|
}
|
|
|
|
/*
|
|
* While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
|
|
* contain the pointer to the queued pwq. Once execution starts, the flag
|
|
* is cleared and the high bits contain OFFQ flags and pool ID.
|
|
*
|
|
* set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
|
|
* and clear_work_data() can be used to set the pwq, pool or clear
|
|
* work->data. These functions should only be called while the work is
|
|
* owned - ie. while the PENDING bit is set.
|
|
*
|
|
* get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
|
|
* corresponding to a work. Pool is available once the work has been
|
|
* queued anywhere after initialization until it is sync canceled. pwq is
|
|
* available only while the work item is queued.
|
|
*
|
|
* %WORK_OFFQ_CANCELING is used to mark a work item which is being
|
|
* canceled. While being canceled, a work item may have its PENDING set
|
|
* but stay off timer and worklist for arbitrarily long and nobody should
|
|
* try to steal the PENDING bit.
|
|
*/
|
|
static inline void set_work_data(struct work_struct *work, unsigned long data,
|
|
unsigned long flags)
|
|
{
|
|
WARN_ON_ONCE(!work_pending(work));
|
|
atomic_long_set(&work->data, data | flags | work_static(work));
|
|
}
|
|
|
|
static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq,
|
|
unsigned long extra_flags)
|
|
{
|
|
set_work_data(work, (unsigned long)pwq,
|
|
WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags);
|
|
}
|
|
|
|
static void set_work_pool_and_keep_pending(struct work_struct *work,
|
|
int pool_id)
|
|
{
|
|
set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT,
|
|
WORK_STRUCT_PENDING);
|
|
}
|
|
|
|
static void set_work_pool_and_clear_pending(struct work_struct *work,
|
|
int pool_id)
|
|
{
|
|
/*
|
|
* The following wmb is paired with the implied mb in
|
|
* test_and_set_bit(PENDING) and ensures all updates to @work made
|
|
* here are visible to and precede any updates by the next PENDING
|
|
* owner.
|
|
*/
|
|
smp_wmb();
|
|
set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0);
|
|
}
|
|
|
|
static void clear_work_data(struct work_struct *work)
|
|
{
|
|
smp_wmb(); /* see set_work_pool_and_clear_pending() */
|
|
set_work_data(work, WORK_STRUCT_NO_POOL, 0);
|
|
}
|
|
|
|
static struct pool_workqueue *get_work_pwq(struct work_struct *work)
|
|
{
|
|
unsigned long data = atomic_long_read(&work->data);
|
|
|
|
if (data & WORK_STRUCT_PWQ)
|
|
return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
|
|
else
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* get_work_pool - return the worker_pool a given work was associated with
|
|
* @work: the work item of interest
|
|
*
|
|
* Pools are created and destroyed under wq_pool_mutex, and allows read
|
|
* access under sched-RCU read lock. As such, this function should be
|
|
* called under wq_pool_mutex or with preemption disabled.
|
|
*
|
|
* All fields of the returned pool are accessible as long as the above
|
|
* mentioned locking is in effect. If the returned pool needs to be used
|
|
* beyond the critical section, the caller is responsible for ensuring the
|
|
* returned pool is and stays online.
|
|
*
|
|
* Return: The worker_pool @work was last associated with. %NULL if none.
|
|
*/
|
|
static struct worker_pool *get_work_pool(struct work_struct *work)
|
|
{
|
|
unsigned long data = atomic_long_read(&work->data);
|
|
int pool_id;
|
|
|
|
assert_rcu_or_pool_mutex();
|
|
|
|
if (data & WORK_STRUCT_PWQ)
|
|
return ((struct pool_workqueue *)
|
|
(data & WORK_STRUCT_WQ_DATA_MASK))->pool;
|
|
|
|
pool_id = data >> WORK_OFFQ_POOL_SHIFT;
|
|
if (pool_id == WORK_OFFQ_POOL_NONE)
|
|
return NULL;
|
|
|
|
return idr_find(&worker_pool_idr, pool_id);
|
|
}
|
|
|
|
/**
|
|
* get_work_pool_id - return the worker pool ID a given work is associated with
|
|
* @work: the work item of interest
|
|
*
|
|
* Return: The worker_pool ID @work was last associated with.
|
|
* %WORK_OFFQ_POOL_NONE if none.
|
|
*/
|
|
static int get_work_pool_id(struct work_struct *work)
|
|
{
|
|
unsigned long data = atomic_long_read(&work->data);
|
|
|
|
if (data & WORK_STRUCT_PWQ)
|
|
return ((struct pool_workqueue *)
|
|
(data & WORK_STRUCT_WQ_DATA_MASK))->pool->id;
|
|
|
|
return data >> WORK_OFFQ_POOL_SHIFT;
|
|
}
|
|
|
|
static void mark_work_canceling(struct work_struct *work)
|
|
{
|
|
unsigned long pool_id = get_work_pool_id(work);
|
|
|
|
pool_id <<= WORK_OFFQ_POOL_SHIFT;
|
|
set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING);
|
|
}
|
|
|
|
static bool work_is_canceling(struct work_struct *work)
|
|
{
|
|
unsigned long data = atomic_long_read(&work->data);
|
|
|
|
return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING);
|
|
}
|
|
|
|
/*
|
|
* Policy functions. These define the policies on how the global worker
|
|
* pools are managed. Unless noted otherwise, these functions assume that
|
|
* they're being called with pool->lock held.
|
|
*/
|
|
|
|
static bool __need_more_worker(struct worker_pool *pool)
|
|
{
|
|
return !atomic_read(&pool->nr_running);
|
|
}
|
|
|
|
/*
|
|
* Need to wake up a worker? Called from anything but currently
|
|
* running workers.
|
|
*
|
|
* Note that, because unbound workers never contribute to nr_running, this
|
|
* function will always return %true for unbound pools as long as the
|
|
* worklist isn't empty.
|
|
*/
|
|
static bool need_more_worker(struct worker_pool *pool)
|
|
{
|
|
return !list_empty(&pool->worklist) && __need_more_worker(pool);
|
|
}
|
|
|
|
/* Can I start working? Called from busy but !running workers. */
|
|
static bool may_start_working(struct worker_pool *pool)
|
|
{
|
|
return pool->nr_idle;
|
|
}
|
|
|
|
/* Do I need to keep working? Called from currently running workers. */
|
|
static bool keep_working(struct worker_pool *pool)
|
|
{
|
|
return !list_empty(&pool->worklist) &&
|
|
atomic_read(&pool->nr_running) <= 1;
|
|
}
|
|
|
|
/* Do we need a new worker? Called from manager. */
|
|
static bool need_to_create_worker(struct worker_pool *pool)
|
|
{
|
|
return need_more_worker(pool) && !may_start_working(pool);
|
|
}
|
|
|
|
/* Do we have too many workers and should some go away? */
|
|
static bool too_many_workers(struct worker_pool *pool)
|
|
{
|
|
bool managing = mutex_is_locked(&pool->manager_arb);
|
|
int nr_idle = pool->nr_idle + managing; /* manager is considered idle */
|
|
int nr_busy = pool->nr_workers - nr_idle;
|
|
|
|
return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
|
|
}
|
|
|
|
/*
|
|
* Wake up functions.
|
|
*/
|
|
|
|
/* Return the first idle worker. Safe with preemption disabled */
|
|
static struct worker *first_idle_worker(struct worker_pool *pool)
|
|
{
|
|
if (unlikely(list_empty(&pool->idle_list)))
|
|
return NULL;
|
|
|
|
return list_first_entry(&pool->idle_list, struct worker, entry);
|
|
}
|
|
|
|
/**
|
|
* wake_up_worker - wake up an idle worker
|
|
* @pool: worker pool to wake worker from
|
|
*
|
|
* Wake up the first idle worker of @pool.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(pool->lock).
|
|
*/
|
|
static void wake_up_worker(struct worker_pool *pool)
|
|
{
|
|
struct worker *worker = first_idle_worker(pool);
|
|
|
|
if (likely(worker))
|
|
wake_up_process(worker->task);
|
|
}
|
|
|
|
/**
|
|
* wq_worker_waking_up - a worker is waking up
|
|
* @task: task waking up
|
|
* @cpu: CPU @task is waking up to
|
|
*
|
|
* This function is called during try_to_wake_up() when a worker is
|
|
* being awoken.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(rq->lock)
|
|
*/
|
|
void wq_worker_waking_up(struct task_struct *task, int cpu)
|
|
{
|
|
struct worker *worker = kthread_data(task);
|
|
|
|
if (!(worker->flags & WORKER_NOT_RUNNING)) {
|
|
WARN_ON_ONCE(worker->pool->cpu != cpu);
|
|
atomic_inc(&worker->pool->nr_running);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* wq_worker_sleeping - a worker is going to sleep
|
|
* @task: task going to sleep
|
|
* @cpu: CPU in question, must be the current CPU number
|
|
*
|
|
* This function is called during schedule() when a busy worker is
|
|
* going to sleep. Worker on the same cpu can be woken up by
|
|
* returning pointer to its task.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(rq->lock)
|
|
*
|
|
* Return:
|
|
* Worker task on @cpu to wake up, %NULL if none.
|
|
*/
|
|
struct task_struct *wq_worker_sleeping(struct task_struct *task, int cpu)
|
|
{
|
|
struct worker *worker = kthread_data(task), *to_wakeup = NULL;
|
|
struct worker_pool *pool;
|
|
|
|
/*
|
|
* Rescuers, which may not have all the fields set up like normal
|
|
* workers, also reach here, let's not access anything before
|
|
* checking NOT_RUNNING.
|
|
*/
|
|
if (worker->flags & WORKER_NOT_RUNNING)
|
|
return NULL;
|
|
|
|
pool = worker->pool;
|
|
|
|
/* this can only happen on the local cpu */
|
|
if (WARN_ON_ONCE(cpu != raw_smp_processor_id() || pool->cpu != cpu))
|
|
return NULL;
|
|
|
|
/*
|
|
* The counterpart of the following dec_and_test, implied mb,
|
|
* worklist not empty test sequence is in insert_work().
|
|
* Please read comment there.
|
|
*
|
|
* NOT_RUNNING is clear. This means that we're bound to and
|
|
* running on the local cpu w/ rq lock held and preemption
|
|
* disabled, which in turn means that none else could be
|
|
* manipulating idle_list, so dereferencing idle_list without pool
|
|
* lock is safe.
|
|
*/
|
|
if (atomic_dec_and_test(&pool->nr_running) &&
|
|
!list_empty(&pool->worklist))
|
|
to_wakeup = first_idle_worker(pool);
|
|
return to_wakeup ? to_wakeup->task : NULL;
|
|
}
|
|
|
|
/**
|
|
* worker_set_flags - set worker flags and adjust nr_running accordingly
|
|
* @worker: self
|
|
* @flags: flags to set
|
|
*
|
|
* Set @flags in @worker->flags and adjust nr_running accordingly.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(pool->lock)
|
|
*/
|
|
static inline void worker_set_flags(struct worker *worker, unsigned int flags)
|
|
{
|
|
struct worker_pool *pool = worker->pool;
|
|
|
|
WARN_ON_ONCE(worker->task != current);
|
|
|
|
/* If transitioning into NOT_RUNNING, adjust nr_running. */
|
|
if ((flags & WORKER_NOT_RUNNING) &&
|
|
!(worker->flags & WORKER_NOT_RUNNING)) {
|
|
atomic_dec(&pool->nr_running);
|
|
}
|
|
|
|
worker->flags |= flags;
|
|
}
|
|
|
|
/**
|
|
* worker_clr_flags - clear worker flags and adjust nr_running accordingly
|
|
* @worker: self
|
|
* @flags: flags to clear
|
|
*
|
|
* Clear @flags in @worker->flags and adjust nr_running accordingly.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(pool->lock)
|
|
*/
|
|
static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
|
|
{
|
|
struct worker_pool *pool = worker->pool;
|
|
unsigned int oflags = worker->flags;
|
|
|
|
WARN_ON_ONCE(worker->task != current);
|
|
|
|
worker->flags &= ~flags;
|
|
|
|
/*
|
|
* If transitioning out of NOT_RUNNING, increment nr_running. Note
|
|
* that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
|
|
* of multiple flags, not a single flag.
|
|
*/
|
|
if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
|
|
if (!(worker->flags & WORKER_NOT_RUNNING))
|
|
atomic_inc(&pool->nr_running);
|
|
}
|
|
|
|
/**
|
|
* find_worker_executing_work - find worker which is executing a work
|
|
* @pool: pool of interest
|
|
* @work: work to find worker for
|
|
*
|
|
* Find a worker which is executing @work on @pool by searching
|
|
* @pool->busy_hash which is keyed by the address of @work. For a worker
|
|
* to match, its current execution should match the address of @work and
|
|
* its work function. This is to avoid unwanted dependency between
|
|
* unrelated work executions through a work item being recycled while still
|
|
* being executed.
|
|
*
|
|
* This is a bit tricky. A work item may be freed once its execution
|
|
* starts and nothing prevents the freed area from being recycled for
|
|
* another work item. If the same work item address ends up being reused
|
|
* before the original execution finishes, workqueue will identify the
|
|
* recycled work item as currently executing and make it wait until the
|
|
* current execution finishes, introducing an unwanted dependency.
|
|
*
|
|
* This function checks the work item address and work function to avoid
|
|
* false positives. Note that this isn't complete as one may construct a
|
|
* work function which can introduce dependency onto itself through a
|
|
* recycled work item. Well, if somebody wants to shoot oneself in the
|
|
* foot that badly, there's only so much we can do, and if such deadlock
|
|
* actually occurs, it should be easy to locate the culprit work function.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(pool->lock).
|
|
*
|
|
* Return:
|
|
* Pointer to worker which is executing @work if found, %NULL
|
|
* otherwise.
|
|
*/
|
|
static struct worker *find_worker_executing_work(struct worker_pool *pool,
|
|
struct work_struct *work)
|
|
{
|
|
struct worker *worker;
|
|
|
|
hash_for_each_possible(pool->busy_hash, worker, hentry,
|
|
(unsigned long)work)
|
|
if (worker->current_work == work &&
|
|
worker->current_func == work->func)
|
|
return worker;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* move_linked_works - move linked works to a list
|
|
* @work: start of series of works to be scheduled
|
|
* @head: target list to append @work to
|
|
* @nextp: out paramter for nested worklist walking
|
|
*
|
|
* Schedule linked works starting from @work to @head. Work series to
|
|
* be scheduled starts at @work and includes any consecutive work with
|
|
* WORK_STRUCT_LINKED set in its predecessor.
|
|
*
|
|
* If @nextp is not NULL, it's updated to point to the next work of
|
|
* the last scheduled work. This allows move_linked_works() to be
|
|
* nested inside outer list_for_each_entry_safe().
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(pool->lock).
|
|
*/
|
|
static void move_linked_works(struct work_struct *work, struct list_head *head,
|
|
struct work_struct **nextp)
|
|
{
|
|
struct work_struct *n;
|
|
|
|
/*
|
|
* Linked worklist will always end before the end of the list,
|
|
* use NULL for list head.
|
|
*/
|
|
list_for_each_entry_safe_from(work, n, NULL, entry) {
|
|
list_move_tail(&work->entry, head);
|
|
if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If we're already inside safe list traversal and have moved
|
|
* multiple works to the scheduled queue, the next position
|
|
* needs to be updated.
|
|
*/
|
|
if (nextp)
|
|
*nextp = n;
|
|
}
|
|
|
|
/**
|
|
* get_pwq - get an extra reference on the specified pool_workqueue
|
|
* @pwq: pool_workqueue to get
|
|
*
|
|
* Obtain an extra reference on @pwq. The caller should guarantee that
|
|
* @pwq has positive refcnt and be holding the matching pool->lock.
|
|
*/
|
|
static void get_pwq(struct pool_workqueue *pwq)
|
|
{
|
|
lockdep_assert_held(&pwq->pool->lock);
|
|
WARN_ON_ONCE(pwq->refcnt <= 0);
|
|
pwq->refcnt++;
|
|
}
|
|
|
|
/**
|
|
* put_pwq - put a pool_workqueue reference
|
|
* @pwq: pool_workqueue to put
|
|
*
|
|
* Drop a reference of @pwq. If its refcnt reaches zero, schedule its
|
|
* destruction. The caller should be holding the matching pool->lock.
|
|
*/
|
|
static void put_pwq(struct pool_workqueue *pwq)
|
|
{
|
|
lockdep_assert_held(&pwq->pool->lock);
|
|
if (likely(--pwq->refcnt))
|
|
return;
|
|
if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND)))
|
|
return;
|
|
/*
|
|
* @pwq can't be released under pool->lock, bounce to
|
|
* pwq_unbound_release_workfn(). This never recurses on the same
|
|
* pool->lock as this path is taken only for unbound workqueues and
|
|
* the release work item is scheduled on a per-cpu workqueue. To
|
|
* avoid lockdep warning, unbound pool->locks are given lockdep
|
|
* subclass of 1 in get_unbound_pool().
|
|
*/
|
|
schedule_work(&pwq->unbound_release_work);
|
|
}
|
|
|
|
/**
|
|
* put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
|
|
* @pwq: pool_workqueue to put (can be %NULL)
|
|
*
|
|
* put_pwq() with locking. This function also allows %NULL @pwq.
|
|
*/
|
|
static void put_pwq_unlocked(struct pool_workqueue *pwq)
|
|
{
|
|
if (pwq) {
|
|
/*
|
|
* As both pwqs and pools are sched-RCU protected, the
|
|
* following lock operations are safe.
|
|
*/
|
|
spin_lock_irq(&pwq->pool->lock);
|
|
put_pwq(pwq);
|
|
spin_unlock_irq(&pwq->pool->lock);
|
|
}
|
|
}
|
|
|
|
static void pwq_activate_delayed_work(struct work_struct *work)
|
|
{
|
|
struct pool_workqueue *pwq = get_work_pwq(work);
|
|
|
|
trace_workqueue_activate_work(work);
|
|
move_linked_works(work, &pwq->pool->worklist, NULL);
|
|
__clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
|
|
pwq->nr_active++;
|
|
}
|
|
|
|
static void pwq_activate_first_delayed(struct pool_workqueue *pwq)
|
|
{
|
|
struct work_struct *work = list_first_entry(&pwq->delayed_works,
|
|
struct work_struct, entry);
|
|
|
|
pwq_activate_delayed_work(work);
|
|
}
|
|
|
|
/**
|
|
* pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
|
|
* @pwq: pwq of interest
|
|
* @color: color of work which left the queue
|
|
*
|
|
* A work either has completed or is removed from pending queue,
|
|
* decrement nr_in_flight of its pwq and handle workqueue flushing.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(pool->lock).
|
|
*/
|
|
static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color)
|
|
{
|
|
/* uncolored work items don't participate in flushing or nr_active */
|
|
if (color == WORK_NO_COLOR)
|
|
goto out_put;
|
|
|
|
pwq->nr_in_flight[color]--;
|
|
|
|
pwq->nr_active--;
|
|
if (!list_empty(&pwq->delayed_works)) {
|
|
/* one down, submit a delayed one */
|
|
if (pwq->nr_active < pwq->max_active)
|
|
pwq_activate_first_delayed(pwq);
|
|
}
|
|
|
|
/* is flush in progress and are we at the flushing tip? */
|
|
if (likely(pwq->flush_color != color))
|
|
goto out_put;
|
|
|
|
/* are there still in-flight works? */
|
|
if (pwq->nr_in_flight[color])
|
|
goto out_put;
|
|
|
|
/* this pwq is done, clear flush_color */
|
|
pwq->flush_color = -1;
|
|
|
|
/*
|
|
* If this was the last pwq, wake up the first flusher. It
|
|
* will handle the rest.
|
|
*/
|
|
if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush))
|
|
complete(&pwq->wq->first_flusher->done);
|
|
out_put:
|
|
put_pwq(pwq);
|
|
}
|
|
|
|
/**
|
|
* try_to_grab_pending - steal work item from worklist and disable irq
|
|
* @work: work item to steal
|
|
* @is_dwork: @work is a delayed_work
|
|
* @flags: place to store irq state
|
|
*
|
|
* Try to grab PENDING bit of @work. This function can handle @work in any
|
|
* stable state - idle, on timer or on worklist.
|
|
*
|
|
* Return:
|
|
* 1 if @work was pending and we successfully stole PENDING
|
|
* 0 if @work was idle and we claimed PENDING
|
|
* -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
|
|
* -ENOENT if someone else is canceling @work, this state may persist
|
|
* for arbitrarily long
|
|
*
|
|
* Note:
|
|
* On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
|
|
* interrupted while holding PENDING and @work off queue, irq must be
|
|
* disabled on entry. This, combined with delayed_work->timer being
|
|
* irqsafe, ensures that we return -EAGAIN for finite short period of time.
|
|
*
|
|
* On successful return, >= 0, irq is disabled and the caller is
|
|
* responsible for releasing it using local_irq_restore(*@flags).
|
|
*
|
|
* This function is safe to call from any context including IRQ handler.
|
|
*/
|
|
static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
|
|
unsigned long *flags)
|
|
{
|
|
struct worker_pool *pool;
|
|
struct pool_workqueue *pwq;
|
|
|
|
local_irq_save(*flags);
|
|
|
|
/* try to steal the timer if it exists */
|
|
if (is_dwork) {
|
|
struct delayed_work *dwork = to_delayed_work(work);
|
|
|
|
/*
|
|
* dwork->timer is irqsafe. If del_timer() fails, it's
|
|
* guaranteed that the timer is not queued anywhere and not
|
|
* running on the local CPU.
|
|
*/
|
|
if (likely(del_timer(&dwork->timer)))
|
|
return 1;
|
|
}
|
|
|
|
/* try to claim PENDING the normal way */
|
|
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
|
|
return 0;
|
|
|
|
/*
|
|
* The queueing is in progress, or it is already queued. Try to
|
|
* steal it from ->worklist without clearing WORK_STRUCT_PENDING.
|
|
*/
|
|
pool = get_work_pool(work);
|
|
if (!pool)
|
|
goto fail;
|
|
|
|
spin_lock(&pool->lock);
|
|
/*
|
|
* work->data is guaranteed to point to pwq only while the work
|
|
* item is queued on pwq->wq, and both updating work->data to point
|
|
* to pwq on queueing and to pool on dequeueing are done under
|
|
* pwq->pool->lock. This in turn guarantees that, if work->data
|
|
* points to pwq which is associated with a locked pool, the work
|
|
* item is currently queued on that pool.
|
|
*/
|
|
pwq = get_work_pwq(work);
|
|
if (pwq && pwq->pool == pool) {
|
|
debug_work_deactivate(work);
|
|
|
|
/*
|
|
* A delayed work item cannot be grabbed directly because
|
|
* it might have linked NO_COLOR work items which, if left
|
|
* on the delayed_list, will confuse pwq->nr_active
|
|
* management later on and cause stall. Make sure the work
|
|
* item is activated before grabbing.
|
|
*/
|
|
if (*work_data_bits(work) & WORK_STRUCT_DELAYED)
|
|
pwq_activate_delayed_work(work);
|
|
|
|
list_del_init(&work->entry);
|
|
pwq_dec_nr_in_flight(pwq, get_work_color(work));
|
|
|
|
/* work->data points to pwq iff queued, point to pool */
|
|
set_work_pool_and_keep_pending(work, pool->id);
|
|
|
|
spin_unlock(&pool->lock);
|
|
return 1;
|
|
}
|
|
spin_unlock(&pool->lock);
|
|
fail:
|
|
local_irq_restore(*flags);
|
|
if (work_is_canceling(work))
|
|
return -ENOENT;
|
|
cpu_relax();
|
|
return -EAGAIN;
|
|
}
|
|
|
|
/**
|
|
* insert_work - insert a work into a pool
|
|
* @pwq: pwq @work belongs to
|
|
* @work: work to insert
|
|
* @head: insertion point
|
|
* @extra_flags: extra WORK_STRUCT_* flags to set
|
|
*
|
|
* Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
|
|
* work_struct flags.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(pool->lock).
|
|
*/
|
|
static void insert_work(struct pool_workqueue *pwq, struct work_struct *work,
|
|
struct list_head *head, unsigned int extra_flags)
|
|
{
|
|
struct worker_pool *pool = pwq->pool;
|
|
|
|
/* we own @work, set data and link */
|
|
set_work_pwq(work, pwq, extra_flags);
|
|
list_add_tail(&work->entry, head);
|
|
get_pwq(pwq);
|
|
|
|
/*
|
|
* Ensure either wq_worker_sleeping() sees the above
|
|
* list_add_tail() or we see zero nr_running to avoid workers lying
|
|
* around lazily while there are works to be processed.
|
|
*/
|
|
smp_mb();
|
|
|
|
if (__need_more_worker(pool))
|
|
wake_up_worker(pool);
|
|
}
|
|
|
|
/*
|
|
* Test whether @work is being queued from another work executing on the
|
|
* same workqueue.
|
|
*/
|
|
static bool is_chained_work(struct workqueue_struct *wq)
|
|
{
|
|
struct worker *worker;
|
|
|
|
worker = current_wq_worker();
|
|
/*
|
|
* Return %true iff I'm a worker execuing a work item on @wq. If
|
|
* I'm @worker, it's safe to dereference it without locking.
|
|
*/
|
|
return worker && worker->current_pwq->wq == wq;
|
|
}
|
|
|
|
static void __queue_work(int cpu, struct workqueue_struct *wq,
|
|
struct work_struct *work)
|
|
{
|
|
struct pool_workqueue *pwq;
|
|
struct worker_pool *last_pool;
|
|
struct list_head *worklist;
|
|
unsigned int work_flags;
|
|
unsigned int req_cpu = cpu;
|
|
|
|
/*
|
|
* While a work item is PENDING && off queue, a task trying to
|
|
* steal the PENDING will busy-loop waiting for it to either get
|
|
* queued or lose PENDING. Grabbing PENDING and queueing should
|
|
* happen with IRQ disabled.
|
|
*/
|
|
WARN_ON_ONCE(!irqs_disabled());
|
|
|
|
debug_work_activate(work);
|
|
|
|
/* if draining, only works from the same workqueue are allowed */
|
|
if (unlikely(wq->flags & __WQ_DRAINING) &&
|
|
WARN_ON_ONCE(!is_chained_work(wq)))
|
|
return;
|
|
retry:
|
|
if (req_cpu == WORK_CPU_UNBOUND)
|
|
cpu = raw_smp_processor_id();
|
|
|
|
/* pwq which will be used unless @work is executing elsewhere */
|
|
if (!(wq->flags & WQ_UNBOUND))
|
|
pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
|
|
else
|
|
pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
|
|
|
|
/*
|
|
* If @work was previously on a different pool, it might still be
|
|
* running there, in which case the work needs to be queued on that
|
|
* pool to guarantee non-reentrancy.
|
|
*/
|
|
last_pool = get_work_pool(work);
|
|
if (last_pool && last_pool != pwq->pool) {
|
|
struct worker *worker;
|
|
|
|
spin_lock(&last_pool->lock);
|
|
|
|
worker = find_worker_executing_work(last_pool, work);
|
|
|
|
if (worker && worker->current_pwq->wq == wq) {
|
|
pwq = worker->current_pwq;
|
|
} else {
|
|
/* meh... not running there, queue here */
|
|
spin_unlock(&last_pool->lock);
|
|
spin_lock(&pwq->pool->lock);
|
|
}
|
|
} else {
|
|
spin_lock(&pwq->pool->lock);
|
|
}
|
|
|
|
/*
|
|
* pwq is determined and locked. For unbound pools, we could have
|
|
* raced with pwq release and it could already be dead. If its
|
|
* refcnt is zero, repeat pwq selection. Note that pwqs never die
|
|
* without another pwq replacing it in the numa_pwq_tbl or while
|
|
* work items are executing on it, so the retrying is guaranteed to
|
|
* make forward-progress.
|
|
*/
|
|
if (unlikely(!pwq->refcnt)) {
|
|
if (wq->flags & WQ_UNBOUND) {
|
|
spin_unlock(&pwq->pool->lock);
|
|
cpu_relax();
|
|
goto retry;
|
|
}
|
|
/* oops */
|
|
WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",
|
|
wq->name, cpu);
|
|
}
|
|
|
|
/* pwq determined, queue */
|
|
trace_workqueue_queue_work(req_cpu, pwq, work);
|
|
|
|
if (WARN_ON(!list_empty(&work->entry))) {
|
|
spin_unlock(&pwq->pool->lock);
|
|
return;
|
|
}
|
|
|
|
pwq->nr_in_flight[pwq->work_color]++;
|
|
work_flags = work_color_to_flags(pwq->work_color);
|
|
|
|
if (likely(pwq->nr_active < pwq->max_active)) {
|
|
trace_workqueue_activate_work(work);
|
|
pwq->nr_active++;
|
|
worklist = &pwq->pool->worklist;
|
|
} else {
|
|
work_flags |= WORK_STRUCT_DELAYED;
|
|
worklist = &pwq->delayed_works;
|
|
}
|
|
|
|
insert_work(pwq, work, worklist, work_flags);
|
|
|
|
spin_unlock(&pwq->pool->lock);
|
|
}
|
|
|
|
/**
|
|
* queue_work_on - queue work on specific cpu
|
|
* @cpu: CPU number to execute work on
|
|
* @wq: workqueue to use
|
|
* @work: work to queue
|
|
*
|
|
* We queue the work to a specific CPU, the caller must ensure it
|
|
* can't go away.
|
|
*
|
|
* Return: %false if @work was already on a queue, %true otherwise.
|
|
*/
|
|
bool queue_work_on(int cpu, struct workqueue_struct *wq,
|
|
struct work_struct *work)
|
|
{
|
|
bool ret = false;
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
|
|
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
|
|
__queue_work(cpu, wq, work);
|
|
ret = true;
|
|
}
|
|
|
|
local_irq_restore(flags);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(queue_work_on);
|
|
|
|
void delayed_work_timer_fn(unsigned long __data)
|
|
{
|
|
struct delayed_work *dwork = (struct delayed_work *)__data;
|
|
|
|
/* should have been called from irqsafe timer with irq already off */
|
|
__queue_work(dwork->cpu, dwork->wq, &dwork->work);
|
|
}
|
|
EXPORT_SYMBOL(delayed_work_timer_fn);
|
|
|
|
static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
|
|
struct delayed_work *dwork, unsigned long delay)
|
|
{
|
|
struct timer_list *timer = &dwork->timer;
|
|
struct work_struct *work = &dwork->work;
|
|
|
|
WARN_ON_ONCE(timer->function != delayed_work_timer_fn ||
|
|
timer->data != (unsigned long)dwork);
|
|
WARN_ON_ONCE(timer_pending(timer));
|
|
WARN_ON_ONCE(!list_empty(&work->entry));
|
|
|
|
/*
|
|
* If @delay is 0, queue @dwork->work immediately. This is for
|
|
* both optimization and correctness. The earliest @timer can
|
|
* expire is on the closest next tick and delayed_work users depend
|
|
* on that there's no such delay when @delay is 0.
|
|
*/
|
|
if (!delay) {
|
|
__queue_work(cpu, wq, &dwork->work);
|
|
return;
|
|
}
|
|
|
|
timer_stats_timer_set_start_info(&dwork->timer);
|
|
|
|
dwork->wq = wq;
|
|
dwork->cpu = cpu;
|
|
timer->expires = jiffies + delay;
|
|
|
|
if (unlikely(cpu != WORK_CPU_UNBOUND))
|
|
add_timer_on(timer, cpu);
|
|
else
|
|
add_timer(timer);
|
|
}
|
|
|
|
/**
|
|
* queue_delayed_work_on - queue work on specific CPU after delay
|
|
* @cpu: CPU number to execute work on
|
|
* @wq: workqueue to use
|
|
* @dwork: work to queue
|
|
* @delay: number of jiffies to wait before queueing
|
|
*
|
|
* Return: %false if @work was already on a queue, %true otherwise. If
|
|
* @delay is zero and @dwork is idle, it will be scheduled for immediate
|
|
* execution.
|
|
*/
|
|
bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
|
|
struct delayed_work *dwork, unsigned long delay)
|
|
{
|
|
struct work_struct *work = &dwork->work;
|
|
bool ret = false;
|
|
unsigned long flags;
|
|
|
|
/* read the comment in __queue_work() */
|
|
local_irq_save(flags);
|
|
|
|
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
|
|
__queue_delayed_work(cpu, wq, dwork, delay);
|
|
ret = true;
|
|
}
|
|
|
|
local_irq_restore(flags);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(queue_delayed_work_on);
|
|
|
|
/**
|
|
* mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
|
|
* @cpu: CPU number to execute work on
|
|
* @wq: workqueue to use
|
|
* @dwork: work to queue
|
|
* @delay: number of jiffies to wait before queueing
|
|
*
|
|
* If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
|
|
* modify @dwork's timer so that it expires after @delay. If @delay is
|
|
* zero, @work is guaranteed to be scheduled immediately regardless of its
|
|
* current state.
|
|
*
|
|
* Return: %false if @dwork was idle and queued, %true if @dwork was
|
|
* pending and its timer was modified.
|
|
*
|
|
* This function is safe to call from any context including IRQ handler.
|
|
* See try_to_grab_pending() for details.
|
|
*/
|
|
bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
|
|
struct delayed_work *dwork, unsigned long delay)
|
|
{
|
|
unsigned long flags;
|
|
int ret;
|
|
|
|
do {
|
|
ret = try_to_grab_pending(&dwork->work, true, &flags);
|
|
} while (unlikely(ret == -EAGAIN));
|
|
|
|
if (likely(ret >= 0)) {
|
|
__queue_delayed_work(cpu, wq, dwork, delay);
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
/* -ENOENT from try_to_grab_pending() becomes %true */
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mod_delayed_work_on);
|
|
|
|
/**
|
|
* worker_enter_idle - enter idle state
|
|
* @worker: worker which is entering idle state
|
|
*
|
|
* @worker is entering idle state. Update stats and idle timer if
|
|
* necessary.
|
|
*
|
|
* LOCKING:
|
|
* spin_lock_irq(pool->lock).
|
|
*/
|
|
static void worker_enter_idle(struct worker *worker)
|
|
{
|
|
struct worker_pool *pool = worker->pool;
|
|
|
|
if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) ||
|
|
WARN_ON_ONCE(!list_empty(&worker->entry) &&
|
|
(worker->hentry.next || worker->hentry.pprev)))
|
|
return;
|
|
|
|
/* can't use worker_set_flags(), also called from create_worker() */
|
|
worker->flags |= WORKER_IDLE;
|
|
pool->nr_idle++;
|
|
worker->last_active = jiffies;
|
|
|
|
/* idle_list is LIFO */
|
|
list_add(&worker->entry, &pool->idle_list);
|
|
|
|
if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
|
|
mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
|
|
|
|
/*
|
|
* Sanity check nr_running. Because wq_unbind_fn() releases
|
|
* pool->lock between setting %WORKER_UNBOUND and zapping
|
|
* nr_running, the warning may trigger spuriously. Check iff
|
|
* unbind is not in progress.
|
|
*/
|
|
WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
|
|
pool->nr_workers == pool->nr_idle &&
|
|
atomic_read(&pool->nr_running));
|
|
}
|
|
|
|
/**
|
|
* worker_leave_idle - leave idle state
|
|
* @worker: worker which is leaving idle state
|
|
*
|
|
* @worker is leaving idle state. Update stats.
|
|
*
|
|
* LOCKING:
|
|
* spin_lock_irq(pool->lock).
|
|
*/
|
|
static void worker_leave_idle(struct worker *worker)
|
|
{
|
|
struct worker_pool *pool = worker->pool;
|
|
|
|
if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE)))
|
|
return;
|
|
worker_clr_flags(worker, WORKER_IDLE);
|
|
pool->nr_idle--;
|
|
list_del_init(&worker->entry);
|
|
}
|
|
|
|
static struct worker *alloc_worker(int node)
|
|
{
|
|
struct worker *worker;
|
|
|
|
worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node);
|
|
if (worker) {
|
|
INIT_LIST_HEAD(&worker->entry);
|
|
INIT_LIST_HEAD(&worker->scheduled);
|
|
INIT_LIST_HEAD(&worker->node);
|
|
/* on creation a worker is in !idle && prep state */
|
|
worker->flags = WORKER_PREP;
|
|
}
|
|
return worker;
|
|
}
|
|
|
|
/**
|
|
* worker_attach_to_pool() - attach a worker to a pool
|
|
* @worker: worker to be attached
|
|
* @pool: the target pool
|
|
*
|
|
* Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and
|
|
* cpu-binding of @worker are kept coordinated with the pool across
|
|
* cpu-[un]hotplugs.
|
|
*/
|
|
static void worker_attach_to_pool(struct worker *worker,
|
|
struct worker_pool *pool)
|
|
{
|
|
mutex_lock(&pool->attach_mutex);
|
|
|
|
/*
|
|
* set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
|
|
* online CPUs. It'll be re-applied when any of the CPUs come up.
|
|
*/
|
|
set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
|
|
|
|
/*
|
|
* The pool->attach_mutex ensures %POOL_DISASSOCIATED remains
|
|
* stable across this function. See the comments above the
|
|
* flag definition for details.
|
|
*/
|
|
if (pool->flags & POOL_DISASSOCIATED)
|
|
worker->flags |= WORKER_UNBOUND;
|
|
|
|
list_add_tail(&worker->node, &pool->workers);
|
|
|
|
mutex_unlock(&pool->attach_mutex);
|
|
}
|
|
|
|
/**
|
|
* worker_detach_from_pool() - detach a worker from its pool
|
|
* @worker: worker which is attached to its pool
|
|
* @pool: the pool @worker is attached to
|
|
*
|
|
* Undo the attaching which had been done in worker_attach_to_pool(). The
|
|
* caller worker shouldn't access to the pool after detached except it has
|
|
* other reference to the pool.
|
|
*/
|
|
static void worker_detach_from_pool(struct worker *worker,
|
|
struct worker_pool *pool)
|
|
{
|
|
struct completion *detach_completion = NULL;
|
|
|
|
mutex_lock(&pool->attach_mutex);
|
|
list_del(&worker->node);
|
|
if (list_empty(&pool->workers))
|
|
detach_completion = pool->detach_completion;
|
|
mutex_unlock(&pool->attach_mutex);
|
|
|
|
/* clear leftover flags without pool->lock after it is detached */
|
|
worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND);
|
|
|
|
if (detach_completion)
|
|
complete(detach_completion);
|
|
}
|
|
|
|
/**
|
|
* create_worker - create a new workqueue worker
|
|
* @pool: pool the new worker will belong to
|
|
*
|
|
* Create and start a new worker which is attached to @pool.
|
|
*
|
|
* CONTEXT:
|
|
* Might sleep. Does GFP_KERNEL allocations.
|
|
*
|
|
* Return:
|
|
* Pointer to the newly created worker.
|
|
*/
|
|
static struct worker *create_worker(struct worker_pool *pool)
|
|
{
|
|
struct worker *worker = NULL;
|
|
int id = -1;
|
|
char id_buf[16];
|
|
|
|
/* ID is needed to determine kthread name */
|
|
id = ida_simple_get(&pool->worker_ida, 0, 0, GFP_KERNEL);
|
|
if (id < 0)
|
|
goto fail;
|
|
|
|
worker = alloc_worker(pool->node);
|
|
if (!worker)
|
|
goto fail;
|
|
|
|
worker->pool = pool;
|
|
worker->id = id;
|
|
|
|
if (pool->cpu >= 0)
|
|
snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id,
|
|
pool->attrs->nice < 0 ? "H" : "");
|
|
else
|
|
snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id);
|
|
|
|
worker->task = kthread_create_on_node(worker_thread, worker, pool->node,
|
|
"kworker/%s", id_buf);
|
|
if (IS_ERR(worker->task))
|
|
goto fail;
|
|
|
|
set_user_nice(worker->task, pool->attrs->nice);
|
|
|
|
/* prevent userland from meddling with cpumask of workqueue workers */
|
|
worker->task->flags |= PF_NO_SETAFFINITY;
|
|
|
|
/* successful, attach the worker to the pool */
|
|
worker_attach_to_pool(worker, pool);
|
|
|
|
/* start the newly created worker */
|
|
spin_lock_irq(&pool->lock);
|
|
worker->pool->nr_workers++;
|
|
worker_enter_idle(worker);
|
|
wake_up_process(worker->task);
|
|
spin_unlock_irq(&pool->lock);
|
|
|
|
return worker;
|
|
|
|
fail:
|
|
if (id >= 0)
|
|
ida_simple_remove(&pool->worker_ida, id);
|
|
kfree(worker);
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* destroy_worker - destroy a workqueue worker
|
|
* @worker: worker to be destroyed
|
|
*
|
|
* Destroy @worker and adjust @pool stats accordingly. The worker should
|
|
* be idle.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(pool->lock).
|
|
*/
|
|
static void destroy_worker(struct worker *worker)
|
|
{
|
|
struct worker_pool *pool = worker->pool;
|
|
|
|
lockdep_assert_held(&pool->lock);
|
|
|
|
/* sanity check frenzy */
|
|
if (WARN_ON(worker->current_work) ||
|
|
WARN_ON(!list_empty(&worker->scheduled)) ||
|
|
WARN_ON(!(worker->flags & WORKER_IDLE)))
|
|
return;
|
|
|
|
pool->nr_workers--;
|
|
pool->nr_idle--;
|
|
|
|
list_del_init(&worker->entry);
|
|
worker->flags |= WORKER_DIE;
|
|
wake_up_process(worker->task);
|
|
}
|
|
|
|
static void idle_worker_timeout(unsigned long __pool)
|
|
{
|
|
struct worker_pool *pool = (void *)__pool;
|
|
|
|
spin_lock_irq(&pool->lock);
|
|
|
|
while (too_many_workers(pool)) {
|
|
struct worker *worker;
|
|
unsigned long expires;
|
|
|
|
/* idle_list is kept in LIFO order, check the last one */
|
|
worker = list_entry(pool->idle_list.prev, struct worker, entry);
|
|
expires = worker->last_active + IDLE_WORKER_TIMEOUT;
|
|
|
|
if (time_before(jiffies, expires)) {
|
|
mod_timer(&pool->idle_timer, expires);
|
|
break;
|
|
}
|
|
|
|
destroy_worker(worker);
|
|
}
|
|
|
|
spin_unlock_irq(&pool->lock);
|
|
}
|
|
|
|
static void send_mayday(struct work_struct *work)
|
|
{
|
|
struct pool_workqueue *pwq = get_work_pwq(work);
|
|
struct workqueue_struct *wq = pwq->wq;
|
|
|
|
lockdep_assert_held(&wq_mayday_lock);
|
|
|
|
if (!wq->rescuer)
|
|
return;
|
|
|
|
/* mayday mayday mayday */
|
|
if (list_empty(&pwq->mayday_node)) {
|
|
/*
|
|
* If @pwq is for an unbound wq, its base ref may be put at
|
|
* any time due to an attribute change. Pin @pwq until the
|
|
* rescuer is done with it.
|
|
*/
|
|
get_pwq(pwq);
|
|
list_add_tail(&pwq->mayday_node, &wq->maydays);
|
|
wake_up_process(wq->rescuer->task);
|
|
}
|
|
}
|
|
|
|
static void pool_mayday_timeout(unsigned long __pool)
|
|
{
|
|
struct worker_pool *pool = (void *)__pool;
|
|
struct work_struct *work;
|
|
|
|
spin_lock_irq(&wq_mayday_lock); /* for wq->maydays */
|
|
spin_lock(&pool->lock);
|
|
|
|
if (need_to_create_worker(pool)) {
|
|
/*
|
|
* We've been trying to create a new worker but
|
|
* haven't been successful. We might be hitting an
|
|
* allocation deadlock. Send distress signals to
|
|
* rescuers.
|
|
*/
|
|
list_for_each_entry(work, &pool->worklist, entry)
|
|
send_mayday(work);
|
|
}
|
|
|
|
spin_unlock(&pool->lock);
|
|
spin_unlock_irq(&wq_mayday_lock);
|
|
|
|
mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
|
|
}
|
|
|
|
/**
|
|
* maybe_create_worker - create a new worker if necessary
|
|
* @pool: pool to create a new worker for
|
|
*
|
|
* Create a new worker for @pool if necessary. @pool is guaranteed to
|
|
* have at least one idle worker on return from this function. If
|
|
* creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
|
|
* sent to all rescuers with works scheduled on @pool to resolve
|
|
* possible allocation deadlock.
|
|
*
|
|
* On return, need_to_create_worker() is guaranteed to be %false and
|
|
* may_start_working() %true.
|
|
*
|
|
* LOCKING:
|
|
* spin_lock_irq(pool->lock) which may be released and regrabbed
|
|
* multiple times. Does GFP_KERNEL allocations. Called only from
|
|
* manager.
|
|
*
|
|
* Return:
|
|
* %false if no action was taken and pool->lock stayed locked, %true
|
|
* otherwise.
|
|
*/
|
|
static bool maybe_create_worker(struct worker_pool *pool)
|
|
__releases(&pool->lock)
|
|
__acquires(&pool->lock)
|
|
{
|
|
if (!need_to_create_worker(pool))
|
|
return false;
|
|
restart:
|
|
spin_unlock_irq(&pool->lock);
|
|
|
|
/* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
|
|
mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
|
|
|
|
while (true) {
|
|
if (create_worker(pool) || !need_to_create_worker(pool))
|
|
break;
|
|
|
|
schedule_timeout_interruptible(CREATE_COOLDOWN);
|
|
|
|
if (!need_to_create_worker(pool))
|
|
break;
|
|
}
|
|
|
|
del_timer_sync(&pool->mayday_timer);
|
|
spin_lock_irq(&pool->lock);
|
|
/*
|
|
* This is necessary even after a new worker was just successfully
|
|
* created as @pool->lock was dropped and the new worker might have
|
|
* already become busy.
|
|
*/
|
|
if (need_to_create_worker(pool))
|
|
goto restart;
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* manage_workers - manage worker pool
|
|
* @worker: self
|
|
*
|
|
* Assume the manager role and manage the worker pool @worker belongs
|
|
* to. At any given time, there can be only zero or one manager per
|
|
* pool. The exclusion is handled automatically by this function.
|
|
*
|
|
* The caller can safely start processing works on false return. On
|
|
* true return, it's guaranteed that need_to_create_worker() is false
|
|
* and may_start_working() is true.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(pool->lock) which may be released and regrabbed
|
|
* multiple times. Does GFP_KERNEL allocations.
|
|
*
|
|
* Return:
|
|
* %false if the pool don't need management and the caller can safely start
|
|
* processing works, %true indicates that the function released pool->lock
|
|
* and reacquired it to perform some management function and that the
|
|
* conditions that the caller verified while holding the lock before
|
|
* calling the function might no longer be true.
|
|
*/
|
|
static bool manage_workers(struct worker *worker)
|
|
{
|
|
struct worker_pool *pool = worker->pool;
|
|
bool ret = false;
|
|
|
|
/*
|
|
* Anyone who successfully grabs manager_arb wins the arbitration
|
|
* and becomes the manager. mutex_trylock() on pool->manager_arb
|
|
* failure while holding pool->lock reliably indicates that someone
|
|
* else is managing the pool and the worker which failed trylock
|
|
* can proceed to executing work items. This means that anyone
|
|
* grabbing manager_arb is responsible for actually performing
|
|
* manager duties. If manager_arb is grabbed and released without
|
|
* actual management, the pool may stall indefinitely.
|
|
*/
|
|
if (!mutex_trylock(&pool->manager_arb))
|
|
return ret;
|
|
|
|
ret |= maybe_create_worker(pool);
|
|
|
|
mutex_unlock(&pool->manager_arb);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* process_one_work - process single work
|
|
* @worker: self
|
|
* @work: work to process
|
|
*
|
|
* Process @work. This function contains all the logics necessary to
|
|
* process a single work including synchronization against and
|
|
* interaction with other workers on the same cpu, queueing and
|
|
* flushing. As long as context requirement is met, any worker can
|
|
* call this function to process a work.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(pool->lock) which is released and regrabbed.
|
|
*/
|
|
static void process_one_work(struct worker *worker, struct work_struct *work)
|
|
__releases(&pool->lock)
|
|
__acquires(&pool->lock)
|
|
{
|
|
struct pool_workqueue *pwq = get_work_pwq(work);
|
|
struct worker_pool *pool = worker->pool;
|
|
bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE;
|
|
int work_color;
|
|
struct worker *collision;
|
|
#ifdef CONFIG_LOCKDEP
|
|
/*
|
|
* It is permissible to free the struct work_struct from
|
|
* inside the function that is called from it, this we need to
|
|
* take into account for lockdep too. To avoid bogus "held
|
|
* lock freed" warnings as well as problems when looking into
|
|
* work->lockdep_map, make a copy and use that here.
|
|
*/
|
|
struct lockdep_map lockdep_map;
|
|
|
|
lockdep_copy_map(&lockdep_map, &work->lockdep_map);
|
|
#endif
|
|
/* ensure we're on the correct CPU */
|
|
WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
|
|
raw_smp_processor_id() != pool->cpu);
|
|
|
|
/*
|
|
* A single work shouldn't be executed concurrently by
|
|
* multiple workers on a single cpu. Check whether anyone is
|
|
* already processing the work. If so, defer the work to the
|
|
* currently executing one.
|
|
*/
|
|
collision = find_worker_executing_work(pool, work);
|
|
if (unlikely(collision)) {
|
|
move_linked_works(work, &collision->scheduled, NULL);
|
|
return;
|
|
}
|
|
|
|
/* claim and dequeue */
|
|
debug_work_deactivate(work);
|
|
hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work);
|
|
worker->current_work = work;
|
|
worker->current_func = work->func;
|
|
worker->current_pwq = pwq;
|
|
work_color = get_work_color(work);
|
|
|
|
list_del_init(&work->entry);
|
|
|
|
/*
|
|
* CPU intensive works don't participate in concurrency management.
|
|
* They're the scheduler's responsibility. This takes @worker out
|
|
* of concurrency management and the next code block will chain
|
|
* execution of the pending work items.
|
|
*/
|
|
if (unlikely(cpu_intensive))
|
|
worker_set_flags(worker, WORKER_CPU_INTENSIVE);
|
|
|
|
/*
|
|
* Wake up another worker if necessary. The condition is always
|
|
* false for normal per-cpu workers since nr_running would always
|
|
* be >= 1 at this point. This is used to chain execution of the
|
|
* pending work items for WORKER_NOT_RUNNING workers such as the
|
|
* UNBOUND and CPU_INTENSIVE ones.
|
|
*/
|
|
if (need_more_worker(pool))
|
|
wake_up_worker(pool);
|
|
|
|
/*
|
|
* Record the last pool and clear PENDING which should be the last
|
|
* update to @work. Also, do this inside @pool->lock so that
|
|
* PENDING and queued state changes happen together while IRQ is
|
|
* disabled.
|
|
*/
|
|
set_work_pool_and_clear_pending(work, pool->id);
|
|
|
|
spin_unlock_irq(&pool->lock);
|
|
|
|
lock_map_acquire_read(&pwq->wq->lockdep_map);
|
|
lock_map_acquire(&lockdep_map);
|
|
trace_workqueue_execute_start(work);
|
|
worker->current_func(work);
|
|
/*
|
|
* While we must be careful to not use "work" after this, the trace
|
|
* point will only record its address.
|
|
*/
|
|
trace_workqueue_execute_end(work);
|
|
lock_map_release(&lockdep_map);
|
|
lock_map_release(&pwq->wq->lockdep_map);
|
|
|
|
if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
|
|
pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
|
|
" last function: %pf\n",
|
|
current->comm, preempt_count(), task_pid_nr(current),
|
|
worker->current_func);
|
|
debug_show_held_locks(current);
|
|
dump_stack();
|
|
}
|
|
|
|
/*
|
|
* The following prevents a kworker from hogging CPU on !PREEMPT
|
|
* kernels, where a requeueing work item waiting for something to
|
|
* happen could deadlock with stop_machine as such work item could
|
|
* indefinitely requeue itself while all other CPUs are trapped in
|
|
* stop_machine. At the same time, report a quiescent RCU state so
|
|
* the same condition doesn't freeze RCU.
|
|
*/
|
|
cond_resched_rcu_qs();
|
|
|
|
spin_lock_irq(&pool->lock);
|
|
|
|
/* clear cpu intensive status */
|
|
if (unlikely(cpu_intensive))
|
|
worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
|
|
|
|
/* we're done with it, release */
|
|
hash_del(&worker->hentry);
|
|
worker->current_work = NULL;
|
|
worker->current_func = NULL;
|
|
worker->current_pwq = NULL;
|
|
worker->desc_valid = false;
|
|
pwq_dec_nr_in_flight(pwq, work_color);
|
|
}
|
|
|
|
/**
|
|
* process_scheduled_works - process scheduled works
|
|
* @worker: self
|
|
*
|
|
* Process all scheduled works. Please note that the scheduled list
|
|
* may change while processing a work, so this function repeatedly
|
|
* fetches a work from the top and executes it.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(pool->lock) which may be released and regrabbed
|
|
* multiple times.
|
|
*/
|
|
static void process_scheduled_works(struct worker *worker)
|
|
{
|
|
while (!list_empty(&worker->scheduled)) {
|
|
struct work_struct *work = list_first_entry(&worker->scheduled,
|
|
struct work_struct, entry);
|
|
process_one_work(worker, work);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* worker_thread - the worker thread function
|
|
* @__worker: self
|
|
*
|
|
* The worker thread function. All workers belong to a worker_pool -
|
|
* either a per-cpu one or dynamic unbound one. These workers process all
|
|
* work items regardless of their specific target workqueue. The only
|
|
* exception is work items which belong to workqueues with a rescuer which
|
|
* will be explained in rescuer_thread().
|
|
*
|
|
* Return: 0
|
|
*/
|
|
static int worker_thread(void *__worker)
|
|
{
|
|
struct worker *worker = __worker;
|
|
struct worker_pool *pool = worker->pool;
|
|
|
|
/* tell the scheduler that this is a workqueue worker */
|
|
worker->task->flags |= PF_WQ_WORKER;
|
|
woke_up:
|
|
spin_lock_irq(&pool->lock);
|
|
|
|
/* am I supposed to die? */
|
|
if (unlikely(worker->flags & WORKER_DIE)) {
|
|
spin_unlock_irq(&pool->lock);
|
|
WARN_ON_ONCE(!list_empty(&worker->entry));
|
|
worker->task->flags &= ~PF_WQ_WORKER;
|
|
|
|
set_task_comm(worker->task, "kworker/dying");
|
|
ida_simple_remove(&pool->worker_ida, worker->id);
|
|
worker_detach_from_pool(worker, pool);
|
|
kfree(worker);
|
|
return 0;
|
|
}
|
|
|
|
worker_leave_idle(worker);
|
|
recheck:
|
|
/* no more worker necessary? */
|
|
if (!need_more_worker(pool))
|
|
goto sleep;
|
|
|
|
/* do we need to manage? */
|
|
if (unlikely(!may_start_working(pool)) && manage_workers(worker))
|
|
goto recheck;
|
|
|
|
/*
|
|
* ->scheduled list can only be filled while a worker is
|
|
* preparing to process a work or actually processing it.
|
|
* Make sure nobody diddled with it while I was sleeping.
|
|
*/
|
|
WARN_ON_ONCE(!list_empty(&worker->scheduled));
|
|
|
|
/*
|
|
* Finish PREP stage. We're guaranteed to have at least one idle
|
|
* worker or that someone else has already assumed the manager
|
|
* role. This is where @worker starts participating in concurrency
|
|
* management if applicable and concurrency management is restored
|
|
* after being rebound. See rebind_workers() for details.
|
|
*/
|
|
worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND);
|
|
|
|
do {
|
|
struct work_struct *work =
|
|
list_first_entry(&pool->worklist,
|
|
struct work_struct, entry);
|
|
|
|
if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
|
|
/* optimization path, not strictly necessary */
|
|
process_one_work(worker, work);
|
|
if (unlikely(!list_empty(&worker->scheduled)))
|
|
process_scheduled_works(worker);
|
|
} else {
|
|
move_linked_works(work, &worker->scheduled, NULL);
|
|
process_scheduled_works(worker);
|
|
}
|
|
} while (keep_working(pool));
|
|
|
|
worker_set_flags(worker, WORKER_PREP);
|
|
sleep:
|
|
/*
|
|
* pool->lock is held and there's no work to process and no need to
|
|
* manage, sleep. Workers are woken up only while holding
|
|
* pool->lock or from local cpu, so setting the current state
|
|
* before releasing pool->lock is enough to prevent losing any
|
|
* event.
|
|
*/
|
|
worker_enter_idle(worker);
|
|
__set_current_state(TASK_INTERRUPTIBLE);
|
|
spin_unlock_irq(&pool->lock);
|
|
schedule();
|
|
goto woke_up;
|
|
}
|
|
|
|
/**
|
|
* rescuer_thread - the rescuer thread function
|
|
* @__rescuer: self
|
|
*
|
|
* Workqueue rescuer thread function. There's one rescuer for each
|
|
* workqueue which has WQ_MEM_RECLAIM set.
|
|
*
|
|
* Regular work processing on a pool may block trying to create a new
|
|
* worker which uses GFP_KERNEL allocation which has slight chance of
|
|
* developing into deadlock if some works currently on the same queue
|
|
* need to be processed to satisfy the GFP_KERNEL allocation. This is
|
|
* the problem rescuer solves.
|
|
*
|
|
* When such condition is possible, the pool summons rescuers of all
|
|
* workqueues which have works queued on the pool and let them process
|
|
* those works so that forward progress can be guaranteed.
|
|
*
|
|
* This should happen rarely.
|
|
*
|
|
* Return: 0
|
|
*/
|
|
static int rescuer_thread(void *__rescuer)
|
|
{
|
|
struct worker *rescuer = __rescuer;
|
|
struct workqueue_struct *wq = rescuer->rescue_wq;
|
|
struct list_head *scheduled = &rescuer->scheduled;
|
|
bool should_stop;
|
|
|
|
set_user_nice(current, RESCUER_NICE_LEVEL);
|
|
|
|
/*
|
|
* Mark rescuer as worker too. As WORKER_PREP is never cleared, it
|
|
* doesn't participate in concurrency management.
|
|
*/
|
|
rescuer->task->flags |= PF_WQ_WORKER;
|
|
repeat:
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
|
|
/*
|
|
* By the time the rescuer is requested to stop, the workqueue
|
|
* shouldn't have any work pending, but @wq->maydays may still have
|
|
* pwq(s) queued. This can happen by non-rescuer workers consuming
|
|
* all the work items before the rescuer got to them. Go through
|
|
* @wq->maydays processing before acting on should_stop so that the
|
|
* list is always empty on exit.
|
|
*/
|
|
should_stop = kthread_should_stop();
|
|
|
|
/* see whether any pwq is asking for help */
|
|
spin_lock_irq(&wq_mayday_lock);
|
|
|
|
while (!list_empty(&wq->maydays)) {
|
|
struct pool_workqueue *pwq = list_first_entry(&wq->maydays,
|
|
struct pool_workqueue, mayday_node);
|
|
struct worker_pool *pool = pwq->pool;
|
|
struct work_struct *work, *n;
|
|
|
|
__set_current_state(TASK_RUNNING);
|
|
list_del_init(&pwq->mayday_node);
|
|
|
|
spin_unlock_irq(&wq_mayday_lock);
|
|
|
|
worker_attach_to_pool(rescuer, pool);
|
|
|
|
spin_lock_irq(&pool->lock);
|
|
rescuer->pool = pool;
|
|
|
|
/*
|
|
* Slurp in all works issued via this workqueue and
|
|
* process'em.
|
|
*/
|
|
WARN_ON_ONCE(!list_empty(&rescuer->scheduled));
|
|
list_for_each_entry_safe(work, n, &pool->worklist, entry)
|
|
if (get_work_pwq(work) == pwq)
|
|
move_linked_works(work, scheduled, &n);
|
|
|
|
process_scheduled_works(rescuer);
|
|
|
|
/*
|
|
* Put the reference grabbed by send_mayday(). @pool won't
|
|
* go away while we're still attached to it.
|
|
*/
|
|
put_pwq(pwq);
|
|
|
|
/*
|
|
* Leave this pool. If need_more_worker() is %true, notify a
|
|
* regular worker; otherwise, we end up with 0 concurrency
|
|
* and stalling the execution.
|
|
*/
|
|
if (need_more_worker(pool))
|
|
wake_up_worker(pool);
|
|
|
|
rescuer->pool = NULL;
|
|
spin_unlock_irq(&pool->lock);
|
|
|
|
worker_detach_from_pool(rescuer, pool);
|
|
|
|
spin_lock_irq(&wq_mayday_lock);
|
|
}
|
|
|
|
spin_unlock_irq(&wq_mayday_lock);
|
|
|
|
if (should_stop) {
|
|
__set_current_state(TASK_RUNNING);
|
|
rescuer->task->flags &= ~PF_WQ_WORKER;
|
|
return 0;
|
|
}
|
|
|
|
/* rescuers should never participate in concurrency management */
|
|
WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING));
|
|
schedule();
|
|
goto repeat;
|
|
}
|
|
|
|
struct wq_barrier {
|
|
struct work_struct work;
|
|
struct completion done;
|
|
};
|
|
|
|
static void wq_barrier_func(struct work_struct *work)
|
|
{
|
|
struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
|
|
complete(&barr->done);
|
|
}
|
|
|
|
/**
|
|
* insert_wq_barrier - insert a barrier work
|
|
* @pwq: pwq to insert barrier into
|
|
* @barr: wq_barrier to insert
|
|
* @target: target work to attach @barr to
|
|
* @worker: worker currently executing @target, NULL if @target is not executing
|
|
*
|
|
* @barr is linked to @target such that @barr is completed only after
|
|
* @target finishes execution. Please note that the ordering
|
|
* guarantee is observed only with respect to @target and on the local
|
|
* cpu.
|
|
*
|
|
* Currently, a queued barrier can't be canceled. This is because
|
|
* try_to_grab_pending() can't determine whether the work to be
|
|
* grabbed is at the head of the queue and thus can't clear LINKED
|
|
* flag of the previous work while there must be a valid next work
|
|
* after a work with LINKED flag set.
|
|
*
|
|
* Note that when @worker is non-NULL, @target may be modified
|
|
* underneath us, so we can't reliably determine pwq from @target.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(pool->lock).
|
|
*/
|
|
static void insert_wq_barrier(struct pool_workqueue *pwq,
|
|
struct wq_barrier *barr,
|
|
struct work_struct *target, struct worker *worker)
|
|
{
|
|
struct list_head *head;
|
|
unsigned int linked = 0;
|
|
|
|
/*
|
|
* debugobject calls are safe here even with pool->lock locked
|
|
* as we know for sure that this will not trigger any of the
|
|
* checks and call back into the fixup functions where we
|
|
* might deadlock.
|
|
*/
|
|
INIT_WORK_ONSTACK(&barr->work, wq_barrier_func);
|
|
__set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
|
|
init_completion(&barr->done);
|
|
|
|
/*
|
|
* If @target is currently being executed, schedule the
|
|
* barrier to the worker; otherwise, put it after @target.
|
|
*/
|
|
if (worker)
|
|
head = worker->scheduled.next;
|
|
else {
|
|
unsigned long *bits = work_data_bits(target);
|
|
|
|
head = target->entry.next;
|
|
/* there can already be other linked works, inherit and set */
|
|
linked = *bits & WORK_STRUCT_LINKED;
|
|
__set_bit(WORK_STRUCT_LINKED_BIT, bits);
|
|
}
|
|
|
|
debug_work_activate(&barr->work);
|
|
insert_work(pwq, &barr->work, head,
|
|
work_color_to_flags(WORK_NO_COLOR) | linked);
|
|
}
|
|
|
|
/**
|
|
* flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
|
|
* @wq: workqueue being flushed
|
|
* @flush_color: new flush color, < 0 for no-op
|
|
* @work_color: new work color, < 0 for no-op
|
|
*
|
|
* Prepare pwqs for workqueue flushing.
|
|
*
|
|
* If @flush_color is non-negative, flush_color on all pwqs should be
|
|
* -1. If no pwq has in-flight commands at the specified color, all
|
|
* pwq->flush_color's stay at -1 and %false is returned. If any pwq
|
|
* has in flight commands, its pwq->flush_color is set to
|
|
* @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
|
|
* wakeup logic is armed and %true is returned.
|
|
*
|
|
* The caller should have initialized @wq->first_flusher prior to
|
|
* calling this function with non-negative @flush_color. If
|
|
* @flush_color is negative, no flush color update is done and %false
|
|
* is returned.
|
|
*
|
|
* If @work_color is non-negative, all pwqs should have the same
|
|
* work_color which is previous to @work_color and all will be
|
|
* advanced to @work_color.
|
|
*
|
|
* CONTEXT:
|
|
* mutex_lock(wq->mutex).
|
|
*
|
|
* Return:
|
|
* %true if @flush_color >= 0 and there's something to flush. %false
|
|
* otherwise.
|
|
*/
|
|
static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq,
|
|
int flush_color, int work_color)
|
|
{
|
|
bool wait = false;
|
|
struct pool_workqueue *pwq;
|
|
|
|
if (flush_color >= 0) {
|
|
WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush));
|
|
atomic_set(&wq->nr_pwqs_to_flush, 1);
|
|
}
|
|
|
|
for_each_pwq(pwq, wq) {
|
|
struct worker_pool *pool = pwq->pool;
|
|
|
|
spin_lock_irq(&pool->lock);
|
|
|
|
if (flush_color >= 0) {
|
|
WARN_ON_ONCE(pwq->flush_color != -1);
|
|
|
|
if (pwq->nr_in_flight[flush_color]) {
|
|
pwq->flush_color = flush_color;
|
|
atomic_inc(&wq->nr_pwqs_to_flush);
|
|
wait = true;
|
|
}
|
|
}
|
|
|
|
if (work_color >= 0) {
|
|
WARN_ON_ONCE(work_color != work_next_color(pwq->work_color));
|
|
pwq->work_color = work_color;
|
|
}
|
|
|
|
spin_unlock_irq(&pool->lock);
|
|
}
|
|
|
|
if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush))
|
|
complete(&wq->first_flusher->done);
|
|
|
|
return wait;
|
|
}
|
|
|
|
/**
|
|
* flush_workqueue - ensure that any scheduled work has run to completion.
|
|
* @wq: workqueue to flush
|
|
*
|
|
* This function sleeps until all work items which were queued on entry
|
|
* have finished execution, but it is not livelocked by new incoming ones.
|
|
*/
|
|
void flush_workqueue(struct workqueue_struct *wq)
|
|
{
|
|
struct wq_flusher this_flusher = {
|
|
.list = LIST_HEAD_INIT(this_flusher.list),
|
|
.flush_color = -1,
|
|
.done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
|
|
};
|
|
int next_color;
|
|
|
|
lock_map_acquire(&wq->lockdep_map);
|
|
lock_map_release(&wq->lockdep_map);
|
|
|
|
mutex_lock(&wq->mutex);
|
|
|
|
/*
|
|
* Start-to-wait phase
|
|
*/
|
|
next_color = work_next_color(wq->work_color);
|
|
|
|
if (next_color != wq->flush_color) {
|
|
/*
|
|
* Color space is not full. The current work_color
|
|
* becomes our flush_color and work_color is advanced
|
|
* by one.
|
|
*/
|
|
WARN_ON_ONCE(!list_empty(&wq->flusher_overflow));
|
|
this_flusher.flush_color = wq->work_color;
|
|
wq->work_color = next_color;
|
|
|
|
if (!wq->first_flusher) {
|
|
/* no flush in progress, become the first flusher */
|
|
WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
|
|
|
|
wq->first_flusher = &this_flusher;
|
|
|
|
if (!flush_workqueue_prep_pwqs(wq, wq->flush_color,
|
|
wq->work_color)) {
|
|
/* nothing to flush, done */
|
|
wq->flush_color = next_color;
|
|
wq->first_flusher = NULL;
|
|
goto out_unlock;
|
|
}
|
|
} else {
|
|
/* wait in queue */
|
|
WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color);
|
|
list_add_tail(&this_flusher.list, &wq->flusher_queue);
|
|
flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
|
|
}
|
|
} else {
|
|
/*
|
|
* Oops, color space is full, wait on overflow queue.
|
|
* The next flush completion will assign us
|
|
* flush_color and transfer to flusher_queue.
|
|
*/
|
|
list_add_tail(&this_flusher.list, &wq->flusher_overflow);
|
|
}
|
|
|
|
mutex_unlock(&wq->mutex);
|
|
|
|
wait_for_completion(&this_flusher.done);
|
|
|
|
/*
|
|
* Wake-up-and-cascade phase
|
|
*
|
|
* First flushers are responsible for cascading flushes and
|
|
* handling overflow. Non-first flushers can simply return.
|
|
*/
|
|
if (wq->first_flusher != &this_flusher)
|
|
return;
|
|
|
|
mutex_lock(&wq->mutex);
|
|
|
|
/* we might have raced, check again with mutex held */
|
|
if (wq->first_flusher != &this_flusher)
|
|
goto out_unlock;
|
|
|
|
wq->first_flusher = NULL;
|
|
|
|
WARN_ON_ONCE(!list_empty(&this_flusher.list));
|
|
WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
|
|
|
|
while (true) {
|
|
struct wq_flusher *next, *tmp;
|
|
|
|
/* complete all the flushers sharing the current flush color */
|
|
list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
|
|
if (next->flush_color != wq->flush_color)
|
|
break;
|
|
list_del_init(&next->list);
|
|
complete(&next->done);
|
|
}
|
|
|
|
WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) &&
|
|
wq->flush_color != work_next_color(wq->work_color));
|
|
|
|
/* this flush_color is finished, advance by one */
|
|
wq->flush_color = work_next_color(wq->flush_color);
|
|
|
|
/* one color has been freed, handle overflow queue */
|
|
if (!list_empty(&wq->flusher_overflow)) {
|
|
/*
|
|
* Assign the same color to all overflowed
|
|
* flushers, advance work_color and append to
|
|
* flusher_queue. This is the start-to-wait
|
|
* phase for these overflowed flushers.
|
|
*/
|
|
list_for_each_entry(tmp, &wq->flusher_overflow, list)
|
|
tmp->flush_color = wq->work_color;
|
|
|
|
wq->work_color = work_next_color(wq->work_color);
|
|
|
|
list_splice_tail_init(&wq->flusher_overflow,
|
|
&wq->flusher_queue);
|
|
flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
|
|
}
|
|
|
|
if (list_empty(&wq->flusher_queue)) {
|
|
WARN_ON_ONCE(wq->flush_color != wq->work_color);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Need to flush more colors. Make the next flusher
|
|
* the new first flusher and arm pwqs.
|
|
*/
|
|
WARN_ON_ONCE(wq->flush_color == wq->work_color);
|
|
WARN_ON_ONCE(wq->flush_color != next->flush_color);
|
|
|
|
list_del_init(&next->list);
|
|
wq->first_flusher = next;
|
|
|
|
if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1))
|
|
break;
|
|
|
|
/*
|
|
* Meh... this color is already done, clear first
|
|
* flusher and repeat cascading.
|
|
*/
|
|
wq->first_flusher = NULL;
|
|
}
|
|
|
|
out_unlock:
|
|
mutex_unlock(&wq->mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(flush_workqueue);
|
|
|
|
/**
|
|
* drain_workqueue - drain a workqueue
|
|
* @wq: workqueue to drain
|
|
*
|
|
* Wait until the workqueue becomes empty. While draining is in progress,
|
|
* only chain queueing is allowed. IOW, only currently pending or running
|
|
* work items on @wq can queue further work items on it. @wq is flushed
|
|
* repeatedly until it becomes empty. The number of flushing is detemined
|
|
* by the depth of chaining and should be relatively short. Whine if it
|
|
* takes too long.
|
|
*/
|
|
void drain_workqueue(struct workqueue_struct *wq)
|
|
{
|
|
unsigned int flush_cnt = 0;
|
|
struct pool_workqueue *pwq;
|
|
|
|
/*
|
|
* __queue_work() needs to test whether there are drainers, is much
|
|
* hotter than drain_workqueue() and already looks at @wq->flags.
|
|
* Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
|
|
*/
|
|
mutex_lock(&wq->mutex);
|
|
if (!wq->nr_drainers++)
|
|
wq->flags |= __WQ_DRAINING;
|
|
mutex_unlock(&wq->mutex);
|
|
reflush:
|
|
flush_workqueue(wq);
|
|
|
|
mutex_lock(&wq->mutex);
|
|
|
|
for_each_pwq(pwq, wq) {
|
|
bool drained;
|
|
|
|
spin_lock_irq(&pwq->pool->lock);
|
|
drained = !pwq->nr_active && list_empty(&pwq->delayed_works);
|
|
spin_unlock_irq(&pwq->pool->lock);
|
|
|
|
if (drained)
|
|
continue;
|
|
|
|
if (++flush_cnt == 10 ||
|
|
(flush_cnt % 100 == 0 && flush_cnt <= 1000))
|
|
pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n",
|
|
wq->name, flush_cnt);
|
|
|
|
mutex_unlock(&wq->mutex);
|
|
goto reflush;
|
|
}
|
|
|
|
if (!--wq->nr_drainers)
|
|
wq->flags &= ~__WQ_DRAINING;
|
|
mutex_unlock(&wq->mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(drain_workqueue);
|
|
|
|
static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr)
|
|
{
|
|
struct worker *worker = NULL;
|
|
struct worker_pool *pool;
|
|
struct pool_workqueue *pwq;
|
|
|
|
might_sleep();
|
|
|
|
local_irq_disable();
|
|
pool = get_work_pool(work);
|
|
if (!pool) {
|
|
local_irq_enable();
|
|
return false;
|
|
}
|
|
|
|
spin_lock(&pool->lock);
|
|
/* see the comment in try_to_grab_pending() with the same code */
|
|
pwq = get_work_pwq(work);
|
|
if (pwq) {
|
|
if (unlikely(pwq->pool != pool))
|
|
goto already_gone;
|
|
} else {
|
|
worker = find_worker_executing_work(pool, work);
|
|
if (!worker)
|
|
goto already_gone;
|
|
pwq = worker->current_pwq;
|
|
}
|
|
|
|
insert_wq_barrier(pwq, barr, work, worker);
|
|
spin_unlock_irq(&pool->lock);
|
|
|
|
/*
|
|
* If @max_active is 1 or rescuer is in use, flushing another work
|
|
* item on the same workqueue may lead to deadlock. Make sure the
|
|
* flusher is not running on the same workqueue by verifying write
|
|
* access.
|
|
*/
|
|
if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)
|
|
lock_map_acquire(&pwq->wq->lockdep_map);
|
|
else
|
|
lock_map_acquire_read(&pwq->wq->lockdep_map);
|
|
lock_map_release(&pwq->wq->lockdep_map);
|
|
|
|
return true;
|
|
already_gone:
|
|
spin_unlock_irq(&pool->lock);
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* flush_work - wait for a work to finish executing the last queueing instance
|
|
* @work: the work to flush
|
|
*
|
|
* Wait until @work has finished execution. @work is guaranteed to be idle
|
|
* on return if it hasn't been requeued since flush started.
|
|
*
|
|
* Return:
|
|
* %true if flush_work() waited for the work to finish execution,
|
|
* %false if it was already idle.
|
|
*/
|
|
bool flush_work(struct work_struct *work)
|
|
{
|
|
struct wq_barrier barr;
|
|
|
|
lock_map_acquire(&work->lockdep_map);
|
|
lock_map_release(&work->lockdep_map);
|
|
|
|
if (start_flush_work(work, &barr)) {
|
|
wait_for_completion(&barr.done);
|
|
destroy_work_on_stack(&barr.work);
|
|
return true;
|
|
} else {
|
|
return false;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(flush_work);
|
|
|
|
static bool __cancel_work_timer(struct work_struct *work, bool is_dwork)
|
|
{
|
|
unsigned long flags;
|
|
int ret;
|
|
|
|
do {
|
|
ret = try_to_grab_pending(work, is_dwork, &flags);
|
|
/*
|
|
* If someone else is canceling, wait for the same event it
|
|
* would be waiting for before retrying.
|
|
*/
|
|
if (unlikely(ret == -ENOENT))
|
|
flush_work(work);
|
|
} while (unlikely(ret < 0));
|
|
|
|
/* tell other tasks trying to grab @work to back off */
|
|
mark_work_canceling(work);
|
|
local_irq_restore(flags);
|
|
|
|
flush_work(work);
|
|
clear_work_data(work);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* cancel_work_sync - cancel a work and wait for it to finish
|
|
* @work: the work to cancel
|
|
*
|
|
* Cancel @work and wait for its execution to finish. This function
|
|
* can be used even if the work re-queues itself or migrates to
|
|
* another workqueue. On return from this function, @work is
|
|
* guaranteed to be not pending or executing on any CPU.
|
|
*
|
|
* cancel_work_sync(&delayed_work->work) must not be used for
|
|
* delayed_work's. Use cancel_delayed_work_sync() instead.
|
|
*
|
|
* The caller must ensure that the workqueue on which @work was last
|
|
* queued can't be destroyed before this function returns.
|
|
*
|
|
* Return:
|
|
* %true if @work was pending, %false otherwise.
|
|
*/
|
|
bool cancel_work_sync(struct work_struct *work)
|
|
{
|
|
return __cancel_work_timer(work, false);
|
|
}
|
|
EXPORT_SYMBOL_GPL(cancel_work_sync);
|
|
|
|
/**
|
|
* flush_delayed_work - wait for a dwork to finish executing the last queueing
|
|
* @dwork: the delayed work to flush
|
|
*
|
|
* Delayed timer is cancelled and the pending work is queued for
|
|
* immediate execution. Like flush_work(), this function only
|
|
* considers the last queueing instance of @dwork.
|
|
*
|
|
* Return:
|
|
* %true if flush_work() waited for the work to finish execution,
|
|
* %false if it was already idle.
|
|
*/
|
|
bool flush_delayed_work(struct delayed_work *dwork)
|
|
{
|
|
local_irq_disable();
|
|
if (del_timer_sync(&dwork->timer))
|
|
__queue_work(dwork->cpu, dwork->wq, &dwork->work);
|
|
local_irq_enable();
|
|
return flush_work(&dwork->work);
|
|
}
|
|
EXPORT_SYMBOL(flush_delayed_work);
|
|
|
|
/**
|
|
* cancel_delayed_work - cancel a delayed work
|
|
* @dwork: delayed_work to cancel
|
|
*
|
|
* Kill off a pending delayed_work.
|
|
*
|
|
* Return: %true if @dwork was pending and canceled; %false if it wasn't
|
|
* pending.
|
|
*
|
|
* Note:
|
|
* The work callback function may still be running on return, unless
|
|
* it returns %true and the work doesn't re-arm itself. Explicitly flush or
|
|
* use cancel_delayed_work_sync() to wait on it.
|
|
*
|
|
* This function is safe to call from any context including IRQ handler.
|
|
*/
|
|
bool cancel_delayed_work(struct delayed_work *dwork)
|
|
{
|
|
unsigned long flags;
|
|
int ret;
|
|
|
|
do {
|
|
ret = try_to_grab_pending(&dwork->work, true, &flags);
|
|
} while (unlikely(ret == -EAGAIN));
|
|
|
|
if (unlikely(ret < 0))
|
|
return false;
|
|
|
|
set_work_pool_and_clear_pending(&dwork->work,
|
|
get_work_pool_id(&dwork->work));
|
|
local_irq_restore(flags);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(cancel_delayed_work);
|
|
|
|
/**
|
|
* cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
|
|
* @dwork: the delayed work cancel
|
|
*
|
|
* This is cancel_work_sync() for delayed works.
|
|
*
|
|
* Return:
|
|
* %true if @dwork was pending, %false otherwise.
|
|
*/
|
|
bool cancel_delayed_work_sync(struct delayed_work *dwork)
|
|
{
|
|
return __cancel_work_timer(&dwork->work, true);
|
|
}
|
|
EXPORT_SYMBOL(cancel_delayed_work_sync);
|
|
|
|
/**
|
|
* schedule_on_each_cpu - execute a function synchronously on each online CPU
|
|
* @func: the function to call
|
|
*
|
|
* schedule_on_each_cpu() executes @func on each online CPU using the
|
|
* system workqueue and blocks until all CPUs have completed.
|
|
* schedule_on_each_cpu() is very slow.
|
|
*
|
|
* Return:
|
|
* 0 on success, -errno on failure.
|
|
*/
|
|
int schedule_on_each_cpu(work_func_t func)
|
|
{
|
|
int cpu;
|
|
struct work_struct __percpu *works;
|
|
|
|
works = alloc_percpu(struct work_struct);
|
|
if (!works)
|
|
return -ENOMEM;
|
|
|
|
get_online_cpus();
|
|
|
|
for_each_online_cpu(cpu) {
|
|
struct work_struct *work = per_cpu_ptr(works, cpu);
|
|
|
|
INIT_WORK(work, func);
|
|
schedule_work_on(cpu, work);
|
|
}
|
|
|
|
for_each_online_cpu(cpu)
|
|
flush_work(per_cpu_ptr(works, cpu));
|
|
|
|
put_online_cpus();
|
|
free_percpu(works);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* flush_scheduled_work - ensure that any scheduled work has run to completion.
|
|
*
|
|
* Forces execution of the kernel-global workqueue and blocks until its
|
|
* completion.
|
|
*
|
|
* Think twice before calling this function! It's very easy to get into
|
|
* trouble if you don't take great care. Either of the following situations
|
|
* will lead to deadlock:
|
|
*
|
|
* One of the work items currently on the workqueue needs to acquire
|
|
* a lock held by your code or its caller.
|
|
*
|
|
* Your code is running in the context of a work routine.
|
|
*
|
|
* They will be detected by lockdep when they occur, but the first might not
|
|
* occur very often. It depends on what work items are on the workqueue and
|
|
* what locks they need, which you have no control over.
|
|
*
|
|
* In most situations flushing the entire workqueue is overkill; you merely
|
|
* need to know that a particular work item isn't queued and isn't running.
|
|
* In such cases you should use cancel_delayed_work_sync() or
|
|
* cancel_work_sync() instead.
|
|
*/
|
|
void flush_scheduled_work(void)
|
|
{
|
|
flush_workqueue(system_wq);
|
|
}
|
|
EXPORT_SYMBOL(flush_scheduled_work);
|
|
|
|
/**
|
|
* execute_in_process_context - reliably execute the routine with user context
|
|
* @fn: the function to execute
|
|
* @ew: guaranteed storage for the execute work structure (must
|
|
* be available when the work executes)
|
|
*
|
|
* Executes the function immediately if process context is available,
|
|
* otherwise schedules the function for delayed execution.
|
|
*
|
|
* Return: 0 - function was executed
|
|
* 1 - function was scheduled for execution
|
|
*/
|
|
int execute_in_process_context(work_func_t fn, struct execute_work *ew)
|
|
{
|
|
if (!in_interrupt()) {
|
|
fn(&ew->work);
|
|
return 0;
|
|
}
|
|
|
|
INIT_WORK(&ew->work, fn);
|
|
schedule_work(&ew->work);
|
|
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL_GPL(execute_in_process_context);
|
|
|
|
#ifdef CONFIG_SYSFS
|
|
/*
|
|
* Workqueues with WQ_SYSFS flag set is visible to userland via
|
|
* /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
|
|
* following attributes.
|
|
*
|
|
* per_cpu RO bool : whether the workqueue is per-cpu or unbound
|
|
* max_active RW int : maximum number of in-flight work items
|
|
*
|
|
* Unbound workqueues have the following extra attributes.
|
|
*
|
|
* id RO int : the associated pool ID
|
|
* nice RW int : nice value of the workers
|
|
* cpumask RW mask : bitmask of allowed CPUs for the workers
|
|
*/
|
|
struct wq_device {
|
|
struct workqueue_struct *wq;
|
|
struct device dev;
|
|
};
|
|
|
|
static struct workqueue_struct *dev_to_wq(struct device *dev)
|
|
{
|
|
struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
|
|
|
|
return wq_dev->wq;
|
|
}
|
|
|
|
static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr,
|
|
char *buf)
|
|
{
|
|
struct workqueue_struct *wq = dev_to_wq(dev);
|
|
|
|
return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND));
|
|
}
|
|
static DEVICE_ATTR_RO(per_cpu);
|
|
|
|
static ssize_t max_active_show(struct device *dev,
|
|
struct device_attribute *attr, char *buf)
|
|
{
|
|
struct workqueue_struct *wq = dev_to_wq(dev);
|
|
|
|
return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active);
|
|
}
|
|
|
|
static ssize_t max_active_store(struct device *dev,
|
|
struct device_attribute *attr, const char *buf,
|
|
size_t count)
|
|
{
|
|
struct workqueue_struct *wq = dev_to_wq(dev);
|
|
int val;
|
|
|
|
if (sscanf(buf, "%d", &val) != 1 || val <= 0)
|
|
return -EINVAL;
|
|
|
|
workqueue_set_max_active(wq, val);
|
|
return count;
|
|
}
|
|
static DEVICE_ATTR_RW(max_active);
|
|
|
|
static struct attribute *wq_sysfs_attrs[] = {
|
|
&dev_attr_per_cpu.attr,
|
|
&dev_attr_max_active.attr,
|
|
NULL,
|
|
};
|
|
ATTRIBUTE_GROUPS(wq_sysfs);
|
|
|
|
static ssize_t wq_pool_ids_show(struct device *dev,
|
|
struct device_attribute *attr, char *buf)
|
|
{
|
|
struct workqueue_struct *wq = dev_to_wq(dev);
|
|
const char *delim = "";
|
|
int node, written = 0;
|
|
|
|
rcu_read_lock_sched();
|
|
for_each_node(node) {
|
|
written += scnprintf(buf + written, PAGE_SIZE - written,
|
|
"%s%d:%d", delim, node,
|
|
unbound_pwq_by_node(wq, node)->pool->id);
|
|
delim = " ";
|
|
}
|
|
written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
|
|
rcu_read_unlock_sched();
|
|
|
|
return written;
|
|
}
|
|
|
|
static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr,
|
|
char *buf)
|
|
{
|
|
struct workqueue_struct *wq = dev_to_wq(dev);
|
|
int written;
|
|
|
|
mutex_lock(&wq->mutex);
|
|
written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice);
|
|
mutex_unlock(&wq->mutex);
|
|
|
|
return written;
|
|
}
|
|
|
|
/* prepare workqueue_attrs for sysfs store operations */
|
|
static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq)
|
|
{
|
|
struct workqueue_attrs *attrs;
|
|
|
|
attrs = alloc_workqueue_attrs(GFP_KERNEL);
|
|
if (!attrs)
|
|
return NULL;
|
|
|
|
mutex_lock(&wq->mutex);
|
|
copy_workqueue_attrs(attrs, wq->unbound_attrs);
|
|
mutex_unlock(&wq->mutex);
|
|
return attrs;
|
|
}
|
|
|
|
static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
struct workqueue_struct *wq = dev_to_wq(dev);
|
|
struct workqueue_attrs *attrs;
|
|
int ret;
|
|
|
|
attrs = wq_sysfs_prep_attrs(wq);
|
|
if (!attrs)
|
|
return -ENOMEM;
|
|
|
|
if (sscanf(buf, "%d", &attrs->nice) == 1 &&
|
|
attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE)
|
|
ret = apply_workqueue_attrs(wq, attrs);
|
|
else
|
|
ret = -EINVAL;
|
|
|
|
free_workqueue_attrs(attrs);
|
|
return ret ?: count;
|
|
}
|
|
|
|
static ssize_t wq_cpumask_show(struct device *dev,
|
|
struct device_attribute *attr, char *buf)
|
|
{
|
|
struct workqueue_struct *wq = dev_to_wq(dev);
|
|
int written;
|
|
|
|
mutex_lock(&wq->mutex);
|
|
written = cpumask_scnprintf(buf, PAGE_SIZE, wq->unbound_attrs->cpumask);
|
|
mutex_unlock(&wq->mutex);
|
|
|
|
written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
|
|
return written;
|
|
}
|
|
|
|
static ssize_t wq_cpumask_store(struct device *dev,
|
|
struct device_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
struct workqueue_struct *wq = dev_to_wq(dev);
|
|
struct workqueue_attrs *attrs;
|
|
int ret;
|
|
|
|
attrs = wq_sysfs_prep_attrs(wq);
|
|
if (!attrs)
|
|
return -ENOMEM;
|
|
|
|
ret = cpumask_parse(buf, attrs->cpumask);
|
|
if (!ret)
|
|
ret = apply_workqueue_attrs(wq, attrs);
|
|
|
|
free_workqueue_attrs(attrs);
|
|
return ret ?: count;
|
|
}
|
|
|
|
static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr,
|
|
char *buf)
|
|
{
|
|
struct workqueue_struct *wq = dev_to_wq(dev);
|
|
int written;
|
|
|
|
mutex_lock(&wq->mutex);
|
|
written = scnprintf(buf, PAGE_SIZE, "%d\n",
|
|
!wq->unbound_attrs->no_numa);
|
|
mutex_unlock(&wq->mutex);
|
|
|
|
return written;
|
|
}
|
|
|
|
static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
struct workqueue_struct *wq = dev_to_wq(dev);
|
|
struct workqueue_attrs *attrs;
|
|
int v, ret;
|
|
|
|
attrs = wq_sysfs_prep_attrs(wq);
|
|
if (!attrs)
|
|
return -ENOMEM;
|
|
|
|
ret = -EINVAL;
|
|
if (sscanf(buf, "%d", &v) == 1) {
|
|
attrs->no_numa = !v;
|
|
ret = apply_workqueue_attrs(wq, attrs);
|
|
}
|
|
|
|
free_workqueue_attrs(attrs);
|
|
return ret ?: count;
|
|
}
|
|
|
|
static struct device_attribute wq_sysfs_unbound_attrs[] = {
|
|
__ATTR(pool_ids, 0444, wq_pool_ids_show, NULL),
|
|
__ATTR(nice, 0644, wq_nice_show, wq_nice_store),
|
|
__ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store),
|
|
__ATTR(numa, 0644, wq_numa_show, wq_numa_store),
|
|
__ATTR_NULL,
|
|
};
|
|
|
|
static struct bus_type wq_subsys = {
|
|
.name = "workqueue",
|
|
.dev_groups = wq_sysfs_groups,
|
|
};
|
|
|
|
static int __init wq_sysfs_init(void)
|
|
{
|
|
return subsys_virtual_register(&wq_subsys, NULL);
|
|
}
|
|
core_initcall(wq_sysfs_init);
|
|
|
|
static void wq_device_release(struct device *dev)
|
|
{
|
|
struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
|
|
|
|
kfree(wq_dev);
|
|
}
|
|
|
|
/**
|
|
* workqueue_sysfs_register - make a workqueue visible in sysfs
|
|
* @wq: the workqueue to register
|
|
*
|
|
* Expose @wq in sysfs under /sys/bus/workqueue/devices.
|
|
* alloc_workqueue*() automatically calls this function if WQ_SYSFS is set
|
|
* which is the preferred method.
|
|
*
|
|
* Workqueue user should use this function directly iff it wants to apply
|
|
* workqueue_attrs before making the workqueue visible in sysfs; otherwise,
|
|
* apply_workqueue_attrs() may race against userland updating the
|
|
* attributes.
|
|
*
|
|
* Return: 0 on success, -errno on failure.
|
|
*/
|
|
int workqueue_sysfs_register(struct workqueue_struct *wq)
|
|
{
|
|
struct wq_device *wq_dev;
|
|
int ret;
|
|
|
|
/*
|
|
* Adjusting max_active or creating new pwqs by applyting
|
|
* attributes breaks ordering guarantee. Disallow exposing ordered
|
|
* workqueues.
|
|
*/
|
|
if (WARN_ON(wq->flags & __WQ_ORDERED))
|
|
return -EINVAL;
|
|
|
|
wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL);
|
|
if (!wq_dev)
|
|
return -ENOMEM;
|
|
|
|
wq_dev->wq = wq;
|
|
wq_dev->dev.bus = &wq_subsys;
|
|
wq_dev->dev.init_name = wq->name;
|
|
wq_dev->dev.release = wq_device_release;
|
|
|
|
/*
|
|
* unbound_attrs are created separately. Suppress uevent until
|
|
* everything is ready.
|
|
*/
|
|
dev_set_uevent_suppress(&wq_dev->dev, true);
|
|
|
|
ret = device_register(&wq_dev->dev);
|
|
if (ret) {
|
|
kfree(wq_dev);
|
|
wq->wq_dev = NULL;
|
|
return ret;
|
|
}
|
|
|
|
if (wq->flags & WQ_UNBOUND) {
|
|
struct device_attribute *attr;
|
|
|
|
for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) {
|
|
ret = device_create_file(&wq_dev->dev, attr);
|
|
if (ret) {
|
|
device_unregister(&wq_dev->dev);
|
|
wq->wq_dev = NULL;
|
|
return ret;
|
|
}
|
|
}
|
|
}
|
|
|
|
dev_set_uevent_suppress(&wq_dev->dev, false);
|
|
kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* workqueue_sysfs_unregister - undo workqueue_sysfs_register()
|
|
* @wq: the workqueue to unregister
|
|
*
|
|
* If @wq is registered to sysfs by workqueue_sysfs_register(), unregister.
|
|
*/
|
|
static void workqueue_sysfs_unregister(struct workqueue_struct *wq)
|
|
{
|
|
struct wq_device *wq_dev = wq->wq_dev;
|
|
|
|
if (!wq->wq_dev)
|
|
return;
|
|
|
|
wq->wq_dev = NULL;
|
|
device_unregister(&wq_dev->dev);
|
|
}
|
|
#else /* CONFIG_SYSFS */
|
|
static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { }
|
|
#endif /* CONFIG_SYSFS */
|
|
|
|
/**
|
|
* free_workqueue_attrs - free a workqueue_attrs
|
|
* @attrs: workqueue_attrs to free
|
|
*
|
|
* Undo alloc_workqueue_attrs().
|
|
*/
|
|
void free_workqueue_attrs(struct workqueue_attrs *attrs)
|
|
{
|
|
if (attrs) {
|
|
free_cpumask_var(attrs->cpumask);
|
|
kfree(attrs);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* alloc_workqueue_attrs - allocate a workqueue_attrs
|
|
* @gfp_mask: allocation mask to use
|
|
*
|
|
* Allocate a new workqueue_attrs, initialize with default settings and
|
|
* return it.
|
|
*
|
|
* Return: The allocated new workqueue_attr on success. %NULL on failure.
|
|
*/
|
|
struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask)
|
|
{
|
|
struct workqueue_attrs *attrs;
|
|
|
|
attrs = kzalloc(sizeof(*attrs), gfp_mask);
|
|
if (!attrs)
|
|
goto fail;
|
|
if (!alloc_cpumask_var(&attrs->cpumask, gfp_mask))
|
|
goto fail;
|
|
|
|
cpumask_copy(attrs->cpumask, cpu_possible_mask);
|
|
return attrs;
|
|
fail:
|
|
free_workqueue_attrs(attrs);
|
|
return NULL;
|
|
}
|
|
|
|
static void copy_workqueue_attrs(struct workqueue_attrs *to,
|
|
const struct workqueue_attrs *from)
|
|
{
|
|
to->nice = from->nice;
|
|
cpumask_copy(to->cpumask, from->cpumask);
|
|
/*
|
|
* Unlike hash and equality test, this function doesn't ignore
|
|
* ->no_numa as it is used for both pool and wq attrs. Instead,
|
|
* get_unbound_pool() explicitly clears ->no_numa after copying.
|
|
*/
|
|
to->no_numa = from->no_numa;
|
|
}
|
|
|
|
/* hash value of the content of @attr */
|
|
static u32 wqattrs_hash(const struct workqueue_attrs *attrs)
|
|
{
|
|
u32 hash = 0;
|
|
|
|
hash = jhash_1word(attrs->nice, hash);
|
|
hash = jhash(cpumask_bits(attrs->cpumask),
|
|
BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash);
|
|
return hash;
|
|
}
|
|
|
|
/* content equality test */
|
|
static bool wqattrs_equal(const struct workqueue_attrs *a,
|
|
const struct workqueue_attrs *b)
|
|
{
|
|
if (a->nice != b->nice)
|
|
return false;
|
|
if (!cpumask_equal(a->cpumask, b->cpumask))
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* init_worker_pool - initialize a newly zalloc'd worker_pool
|
|
* @pool: worker_pool to initialize
|
|
*
|
|
* Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs.
|
|
*
|
|
* Return: 0 on success, -errno on failure. Even on failure, all fields
|
|
* inside @pool proper are initialized and put_unbound_pool() can be called
|
|
* on @pool safely to release it.
|
|
*/
|
|
static int init_worker_pool(struct worker_pool *pool)
|
|
{
|
|
spin_lock_init(&pool->lock);
|
|
pool->id = -1;
|
|
pool->cpu = -1;
|
|
pool->node = NUMA_NO_NODE;
|
|
pool->flags |= POOL_DISASSOCIATED;
|
|
INIT_LIST_HEAD(&pool->worklist);
|
|
INIT_LIST_HEAD(&pool->idle_list);
|
|
hash_init(pool->busy_hash);
|
|
|
|
init_timer_deferrable(&pool->idle_timer);
|
|
pool->idle_timer.function = idle_worker_timeout;
|
|
pool->idle_timer.data = (unsigned long)pool;
|
|
|
|
setup_timer(&pool->mayday_timer, pool_mayday_timeout,
|
|
(unsigned long)pool);
|
|
|
|
mutex_init(&pool->manager_arb);
|
|
mutex_init(&pool->attach_mutex);
|
|
INIT_LIST_HEAD(&pool->workers);
|
|
|
|
ida_init(&pool->worker_ida);
|
|
INIT_HLIST_NODE(&pool->hash_node);
|
|
pool->refcnt = 1;
|
|
|
|
/* shouldn't fail above this point */
|
|
pool->attrs = alloc_workqueue_attrs(GFP_KERNEL);
|
|
if (!pool->attrs)
|
|
return -ENOMEM;
|
|
return 0;
|
|
}
|
|
|
|
static void rcu_free_pool(struct rcu_head *rcu)
|
|
{
|
|
struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu);
|
|
|
|
ida_destroy(&pool->worker_ida);
|
|
free_workqueue_attrs(pool->attrs);
|
|
kfree(pool);
|
|
}
|
|
|
|
/**
|
|
* put_unbound_pool - put a worker_pool
|
|
* @pool: worker_pool to put
|
|
*
|
|
* Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU
|
|
* safe manner. get_unbound_pool() calls this function on its failure path
|
|
* and this function should be able to release pools which went through,
|
|
* successfully or not, init_worker_pool().
|
|
*
|
|
* Should be called with wq_pool_mutex held.
|
|
*/
|
|
static void put_unbound_pool(struct worker_pool *pool)
|
|
{
|
|
DECLARE_COMPLETION_ONSTACK(detach_completion);
|
|
struct worker *worker;
|
|
|
|
lockdep_assert_held(&wq_pool_mutex);
|
|
|
|
if (--pool->refcnt)
|
|
return;
|
|
|
|
/* sanity checks */
|
|
if (WARN_ON(!(pool->cpu < 0)) ||
|
|
WARN_ON(!list_empty(&pool->worklist)))
|
|
return;
|
|
|
|
/* release id and unhash */
|
|
if (pool->id >= 0)
|
|
idr_remove(&worker_pool_idr, pool->id);
|
|
hash_del(&pool->hash_node);
|
|
|
|
/*
|
|
* Become the manager and destroy all workers. Grabbing
|
|
* manager_arb prevents @pool's workers from blocking on
|
|
* attach_mutex.
|
|
*/
|
|
mutex_lock(&pool->manager_arb);
|
|
|
|
spin_lock_irq(&pool->lock);
|
|
while ((worker = first_idle_worker(pool)))
|
|
destroy_worker(worker);
|
|
WARN_ON(pool->nr_workers || pool->nr_idle);
|
|
spin_unlock_irq(&pool->lock);
|
|
|
|
mutex_lock(&pool->attach_mutex);
|
|
if (!list_empty(&pool->workers))
|
|
pool->detach_completion = &detach_completion;
|
|
mutex_unlock(&pool->attach_mutex);
|
|
|
|
if (pool->detach_completion)
|
|
wait_for_completion(pool->detach_completion);
|
|
|
|
mutex_unlock(&pool->manager_arb);
|
|
|
|
/* shut down the timers */
|
|
del_timer_sync(&pool->idle_timer);
|
|
del_timer_sync(&pool->mayday_timer);
|
|
|
|
/* sched-RCU protected to allow dereferences from get_work_pool() */
|
|
call_rcu_sched(&pool->rcu, rcu_free_pool);
|
|
}
|
|
|
|
/**
|
|
* get_unbound_pool - get a worker_pool with the specified attributes
|
|
* @attrs: the attributes of the worker_pool to get
|
|
*
|
|
* Obtain a worker_pool which has the same attributes as @attrs, bump the
|
|
* reference count and return it. If there already is a matching
|
|
* worker_pool, it will be used; otherwise, this function attempts to
|
|
* create a new one.
|
|
*
|
|
* Should be called with wq_pool_mutex held.
|
|
*
|
|
* Return: On success, a worker_pool with the same attributes as @attrs.
|
|
* On failure, %NULL.
|
|
*/
|
|
static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs)
|
|
{
|
|
u32 hash = wqattrs_hash(attrs);
|
|
struct worker_pool *pool;
|
|
int node;
|
|
|
|
lockdep_assert_held(&wq_pool_mutex);
|
|
|
|
/* do we already have a matching pool? */
|
|
hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) {
|
|
if (wqattrs_equal(pool->attrs, attrs)) {
|
|
pool->refcnt++;
|
|
return pool;
|
|
}
|
|
}
|
|
|
|
/* nope, create a new one */
|
|
pool = kzalloc(sizeof(*pool), GFP_KERNEL);
|
|
if (!pool || init_worker_pool(pool) < 0)
|
|
goto fail;
|
|
|
|
lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */
|
|
copy_workqueue_attrs(pool->attrs, attrs);
|
|
|
|
/*
|
|
* no_numa isn't a worker_pool attribute, always clear it. See
|
|
* 'struct workqueue_attrs' comments for detail.
|
|
*/
|
|
pool->attrs->no_numa = false;
|
|
|
|
/* if cpumask is contained inside a NUMA node, we belong to that node */
|
|
if (wq_numa_enabled) {
|
|
for_each_node(node) {
|
|
if (cpumask_subset(pool->attrs->cpumask,
|
|
wq_numa_possible_cpumask[node])) {
|
|
pool->node = node;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (worker_pool_assign_id(pool) < 0)
|
|
goto fail;
|
|
|
|
/* create and start the initial worker */
|
|
if (!create_worker(pool))
|
|
goto fail;
|
|
|
|
/* install */
|
|
hash_add(unbound_pool_hash, &pool->hash_node, hash);
|
|
|
|
return pool;
|
|
fail:
|
|
if (pool)
|
|
put_unbound_pool(pool);
|
|
return NULL;
|
|
}
|
|
|
|
static void rcu_free_pwq(struct rcu_head *rcu)
|
|
{
|
|
kmem_cache_free(pwq_cache,
|
|
container_of(rcu, struct pool_workqueue, rcu));
|
|
}
|
|
|
|
/*
|
|
* Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt
|
|
* and needs to be destroyed.
|
|
*/
|
|
static void pwq_unbound_release_workfn(struct work_struct *work)
|
|
{
|
|
struct pool_workqueue *pwq = container_of(work, struct pool_workqueue,
|
|
unbound_release_work);
|
|
struct workqueue_struct *wq = pwq->wq;
|
|
struct worker_pool *pool = pwq->pool;
|
|
bool is_last;
|
|
|
|
if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
|
|
return;
|
|
|
|
mutex_lock(&wq->mutex);
|
|
list_del_rcu(&pwq->pwqs_node);
|
|
is_last = list_empty(&wq->pwqs);
|
|
mutex_unlock(&wq->mutex);
|
|
|
|
mutex_lock(&wq_pool_mutex);
|
|
put_unbound_pool(pool);
|
|
mutex_unlock(&wq_pool_mutex);
|
|
|
|
call_rcu_sched(&pwq->rcu, rcu_free_pwq);
|
|
|
|
/*
|
|
* If we're the last pwq going away, @wq is already dead and no one
|
|
* is gonna access it anymore. Free it.
|
|
*/
|
|
if (is_last) {
|
|
free_workqueue_attrs(wq->unbound_attrs);
|
|
kfree(wq);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* pwq_adjust_max_active - update a pwq's max_active to the current setting
|
|
* @pwq: target pool_workqueue
|
|
*
|
|
* If @pwq isn't freezing, set @pwq->max_active to the associated
|
|
* workqueue's saved_max_active and activate delayed work items
|
|
* accordingly. If @pwq is freezing, clear @pwq->max_active to zero.
|
|
*/
|
|
static void pwq_adjust_max_active(struct pool_workqueue *pwq)
|
|
{
|
|
struct workqueue_struct *wq = pwq->wq;
|
|
bool freezable = wq->flags & WQ_FREEZABLE;
|
|
|
|
/* for @wq->saved_max_active */
|
|
lockdep_assert_held(&wq->mutex);
|
|
|
|
/* fast exit for non-freezable wqs */
|
|
if (!freezable && pwq->max_active == wq->saved_max_active)
|
|
return;
|
|
|
|
spin_lock_irq(&pwq->pool->lock);
|
|
|
|
/*
|
|
* During [un]freezing, the caller is responsible for ensuring that
|
|
* this function is called at least once after @workqueue_freezing
|
|
* is updated and visible.
|
|
*/
|
|
if (!freezable || !workqueue_freezing) {
|
|
pwq->max_active = wq->saved_max_active;
|
|
|
|
while (!list_empty(&pwq->delayed_works) &&
|
|
pwq->nr_active < pwq->max_active)
|
|
pwq_activate_first_delayed(pwq);
|
|
|
|
/*
|
|
* Need to kick a worker after thawed or an unbound wq's
|
|
* max_active is bumped. It's a slow path. Do it always.
|
|
*/
|
|
wake_up_worker(pwq->pool);
|
|
} else {
|
|
pwq->max_active = 0;
|
|
}
|
|
|
|
spin_unlock_irq(&pwq->pool->lock);
|
|
}
|
|
|
|
/* initialize newly alloced @pwq which is associated with @wq and @pool */
|
|
static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq,
|
|
struct worker_pool *pool)
|
|
{
|
|
BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK);
|
|
|
|
memset(pwq, 0, sizeof(*pwq));
|
|
|
|
pwq->pool = pool;
|
|
pwq->wq = wq;
|
|
pwq->flush_color = -1;
|
|
pwq->refcnt = 1;
|
|
INIT_LIST_HEAD(&pwq->delayed_works);
|
|
INIT_LIST_HEAD(&pwq->pwqs_node);
|
|
INIT_LIST_HEAD(&pwq->mayday_node);
|
|
INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
|
|
}
|
|
|
|
/* sync @pwq with the current state of its associated wq and link it */
|
|
static void link_pwq(struct pool_workqueue *pwq)
|
|
{
|
|
struct workqueue_struct *wq = pwq->wq;
|
|
|
|
lockdep_assert_held(&wq->mutex);
|
|
|
|
/* may be called multiple times, ignore if already linked */
|
|
if (!list_empty(&pwq->pwqs_node))
|
|
return;
|
|
|
|
/* set the matching work_color */
|
|
pwq->work_color = wq->work_color;
|
|
|
|
/* sync max_active to the current setting */
|
|
pwq_adjust_max_active(pwq);
|
|
|
|
/* link in @pwq */
|
|
list_add_rcu(&pwq->pwqs_node, &wq->pwqs);
|
|
}
|
|
|
|
/* obtain a pool matching @attr and create a pwq associating the pool and @wq */
|
|
static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq,
|
|
const struct workqueue_attrs *attrs)
|
|
{
|
|
struct worker_pool *pool;
|
|
struct pool_workqueue *pwq;
|
|
|
|
lockdep_assert_held(&wq_pool_mutex);
|
|
|
|
pool = get_unbound_pool(attrs);
|
|
if (!pool)
|
|
return NULL;
|
|
|
|
pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node);
|
|
if (!pwq) {
|
|
put_unbound_pool(pool);
|
|
return NULL;
|
|
}
|
|
|
|
init_pwq(pwq, wq, pool);
|
|
return pwq;
|
|
}
|
|
|
|
/* undo alloc_unbound_pwq(), used only in the error path */
|
|
static void free_unbound_pwq(struct pool_workqueue *pwq)
|
|
{
|
|
lockdep_assert_held(&wq_pool_mutex);
|
|
|
|
if (pwq) {
|
|
put_unbound_pool(pwq->pool);
|
|
kmem_cache_free(pwq_cache, pwq);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* wq_calc_node_mask - calculate a wq_attrs' cpumask for the specified node
|
|
* @attrs: the wq_attrs of interest
|
|
* @node: the target NUMA node
|
|
* @cpu_going_down: if >= 0, the CPU to consider as offline
|
|
* @cpumask: outarg, the resulting cpumask
|
|
*
|
|
* Calculate the cpumask a workqueue with @attrs should use on @node. If
|
|
* @cpu_going_down is >= 0, that cpu is considered offline during
|
|
* calculation. The result is stored in @cpumask.
|
|
*
|
|
* If NUMA affinity is not enabled, @attrs->cpumask is always used. If
|
|
* enabled and @node has online CPUs requested by @attrs, the returned
|
|
* cpumask is the intersection of the possible CPUs of @node and
|
|
* @attrs->cpumask.
|
|
*
|
|
* The caller is responsible for ensuring that the cpumask of @node stays
|
|
* stable.
|
|
*
|
|
* Return: %true if the resulting @cpumask is different from @attrs->cpumask,
|
|
* %false if equal.
|
|
*/
|
|
static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node,
|
|
int cpu_going_down, cpumask_t *cpumask)
|
|
{
|
|
if (!wq_numa_enabled || attrs->no_numa)
|
|
goto use_dfl;
|
|
|
|
/* does @node have any online CPUs @attrs wants? */
|
|
cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask);
|
|
if (cpu_going_down >= 0)
|
|
cpumask_clear_cpu(cpu_going_down, cpumask);
|
|
|
|
if (cpumask_empty(cpumask))
|
|
goto use_dfl;
|
|
|
|
/* yeap, return possible CPUs in @node that @attrs wants */
|
|
cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]);
|
|
return !cpumask_equal(cpumask, attrs->cpumask);
|
|
|
|
use_dfl:
|
|
cpumask_copy(cpumask, attrs->cpumask);
|
|
return false;
|
|
}
|
|
|
|
/* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
|
|
static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq,
|
|
int node,
|
|
struct pool_workqueue *pwq)
|
|
{
|
|
struct pool_workqueue *old_pwq;
|
|
|
|
lockdep_assert_held(&wq->mutex);
|
|
|
|
/* link_pwq() can handle duplicate calls */
|
|
link_pwq(pwq);
|
|
|
|
old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
|
|
rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq);
|
|
return old_pwq;
|
|
}
|
|
|
|
/**
|
|
* apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
|
|
* @wq: the target workqueue
|
|
* @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
|
|
*
|
|
* Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
|
|
* machines, this function maps a separate pwq to each NUMA node with
|
|
* possibles CPUs in @attrs->cpumask so that work items are affine to the
|
|
* NUMA node it was issued on. Older pwqs are released as in-flight work
|
|
* items finish. Note that a work item which repeatedly requeues itself
|
|
* back-to-back will stay on its current pwq.
|
|
*
|
|
* Performs GFP_KERNEL allocations.
|
|
*
|
|
* Return: 0 on success and -errno on failure.
|
|
*/
|
|
int apply_workqueue_attrs(struct workqueue_struct *wq,
|
|
const struct workqueue_attrs *attrs)
|
|
{
|
|
struct workqueue_attrs *new_attrs, *tmp_attrs;
|
|
struct pool_workqueue **pwq_tbl, *dfl_pwq;
|
|
int node, ret;
|
|
|
|
/* only unbound workqueues can change attributes */
|
|
if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
|
|
return -EINVAL;
|
|
|
|
/* creating multiple pwqs breaks ordering guarantee */
|
|
if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)))
|
|
return -EINVAL;
|
|
|
|
pwq_tbl = kzalloc(nr_node_ids * sizeof(pwq_tbl[0]), GFP_KERNEL);
|
|
new_attrs = alloc_workqueue_attrs(GFP_KERNEL);
|
|
tmp_attrs = alloc_workqueue_attrs(GFP_KERNEL);
|
|
if (!pwq_tbl || !new_attrs || !tmp_attrs)
|
|
goto enomem;
|
|
|
|
/* make a copy of @attrs and sanitize it */
|
|
copy_workqueue_attrs(new_attrs, attrs);
|
|
cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask);
|
|
|
|
/*
|
|
* We may create multiple pwqs with differing cpumasks. Make a
|
|
* copy of @new_attrs which will be modified and used to obtain
|
|
* pools.
|
|
*/
|
|
copy_workqueue_attrs(tmp_attrs, new_attrs);
|
|
|
|
/*
|
|
* CPUs should stay stable across pwq creations and installations.
|
|
* Pin CPUs, determine the target cpumask for each node and create
|
|
* pwqs accordingly.
|
|
*/
|
|
get_online_cpus();
|
|
|
|
mutex_lock(&wq_pool_mutex);
|
|
|
|
/*
|
|
* If something goes wrong during CPU up/down, we'll fall back to
|
|
* the default pwq covering whole @attrs->cpumask. Always create
|
|
* it even if we don't use it immediately.
|
|
*/
|
|
dfl_pwq = alloc_unbound_pwq(wq, new_attrs);
|
|
if (!dfl_pwq)
|
|
goto enomem_pwq;
|
|
|
|
for_each_node(node) {
|
|
if (wq_calc_node_cpumask(attrs, node, -1, tmp_attrs->cpumask)) {
|
|
pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs);
|
|
if (!pwq_tbl[node])
|
|
goto enomem_pwq;
|
|
} else {
|
|
dfl_pwq->refcnt++;
|
|
pwq_tbl[node] = dfl_pwq;
|
|
}
|
|
}
|
|
|
|
mutex_unlock(&wq_pool_mutex);
|
|
|
|
/* all pwqs have been created successfully, let's install'em */
|
|
mutex_lock(&wq->mutex);
|
|
|
|
copy_workqueue_attrs(wq->unbound_attrs, new_attrs);
|
|
|
|
/* save the previous pwq and install the new one */
|
|
for_each_node(node)
|
|
pwq_tbl[node] = numa_pwq_tbl_install(wq, node, pwq_tbl[node]);
|
|
|
|
/* @dfl_pwq might not have been used, ensure it's linked */
|
|
link_pwq(dfl_pwq);
|
|
swap(wq->dfl_pwq, dfl_pwq);
|
|
|
|
mutex_unlock(&wq->mutex);
|
|
|
|
/* put the old pwqs */
|
|
for_each_node(node)
|
|
put_pwq_unlocked(pwq_tbl[node]);
|
|
put_pwq_unlocked(dfl_pwq);
|
|
|
|
put_online_cpus();
|
|
ret = 0;
|
|
/* fall through */
|
|
out_free:
|
|
free_workqueue_attrs(tmp_attrs);
|
|
free_workqueue_attrs(new_attrs);
|
|
kfree(pwq_tbl);
|
|
return ret;
|
|
|
|
enomem_pwq:
|
|
free_unbound_pwq(dfl_pwq);
|
|
for_each_node(node)
|
|
if (pwq_tbl && pwq_tbl[node] != dfl_pwq)
|
|
free_unbound_pwq(pwq_tbl[node]);
|
|
mutex_unlock(&wq_pool_mutex);
|
|
put_online_cpus();
|
|
enomem:
|
|
ret = -ENOMEM;
|
|
goto out_free;
|
|
}
|
|
|
|
/**
|
|
* wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
|
|
* @wq: the target workqueue
|
|
* @cpu: the CPU coming up or going down
|
|
* @online: whether @cpu is coming up or going down
|
|
*
|
|
* This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
|
|
* %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of
|
|
* @wq accordingly.
|
|
*
|
|
* If NUMA affinity can't be adjusted due to memory allocation failure, it
|
|
* falls back to @wq->dfl_pwq which may not be optimal but is always
|
|
* correct.
|
|
*
|
|
* Note that when the last allowed CPU of a NUMA node goes offline for a
|
|
* workqueue with a cpumask spanning multiple nodes, the workers which were
|
|
* already executing the work items for the workqueue will lose their CPU
|
|
* affinity and may execute on any CPU. This is similar to how per-cpu
|
|
* workqueues behave on CPU_DOWN. If a workqueue user wants strict
|
|
* affinity, it's the user's responsibility to flush the work item from
|
|
* CPU_DOWN_PREPARE.
|
|
*/
|
|
static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
|
|
bool online)
|
|
{
|
|
int node = cpu_to_node(cpu);
|
|
int cpu_off = online ? -1 : cpu;
|
|
struct pool_workqueue *old_pwq = NULL, *pwq;
|
|
struct workqueue_attrs *target_attrs;
|
|
cpumask_t *cpumask;
|
|
|
|
lockdep_assert_held(&wq_pool_mutex);
|
|
|
|
if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND))
|
|
return;
|
|
|
|
/*
|
|
* We don't wanna alloc/free wq_attrs for each wq for each CPU.
|
|
* Let's use a preallocated one. The following buf is protected by
|
|
* CPU hotplug exclusion.
|
|
*/
|
|
target_attrs = wq_update_unbound_numa_attrs_buf;
|
|
cpumask = target_attrs->cpumask;
|
|
|
|
mutex_lock(&wq->mutex);
|
|
if (wq->unbound_attrs->no_numa)
|
|
goto out_unlock;
|
|
|
|
copy_workqueue_attrs(target_attrs, wq->unbound_attrs);
|
|
pwq = unbound_pwq_by_node(wq, node);
|
|
|
|
/*
|
|
* Let's determine what needs to be done. If the target cpumask is
|
|
* different from wq's, we need to compare it to @pwq's and create
|
|
* a new one if they don't match. If the target cpumask equals
|
|
* wq's, the default pwq should be used.
|
|
*/
|
|
if (wq_calc_node_cpumask(wq->unbound_attrs, node, cpu_off, cpumask)) {
|
|
if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))
|
|
goto out_unlock;
|
|
} else {
|
|
goto use_dfl_pwq;
|
|
}
|
|
|
|
mutex_unlock(&wq->mutex);
|
|
|
|
/* create a new pwq */
|
|
pwq = alloc_unbound_pwq(wq, target_attrs);
|
|
if (!pwq) {
|
|
pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
|
|
wq->name);
|
|
mutex_lock(&wq->mutex);
|
|
goto use_dfl_pwq;
|
|
}
|
|
|
|
/*
|
|
* Install the new pwq. As this function is called only from CPU
|
|
* hotplug callbacks and applying a new attrs is wrapped with
|
|
* get/put_online_cpus(), @wq->unbound_attrs couldn't have changed
|
|
* inbetween.
|
|
*/
|
|
mutex_lock(&wq->mutex);
|
|
old_pwq = numa_pwq_tbl_install(wq, node, pwq);
|
|
goto out_unlock;
|
|
|
|
use_dfl_pwq:
|
|
spin_lock_irq(&wq->dfl_pwq->pool->lock);
|
|
get_pwq(wq->dfl_pwq);
|
|
spin_unlock_irq(&wq->dfl_pwq->pool->lock);
|
|
old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq);
|
|
out_unlock:
|
|
mutex_unlock(&wq->mutex);
|
|
put_pwq_unlocked(old_pwq);
|
|
}
|
|
|
|
static int alloc_and_link_pwqs(struct workqueue_struct *wq)
|
|
{
|
|
bool highpri = wq->flags & WQ_HIGHPRI;
|
|
int cpu, ret;
|
|
|
|
if (!(wq->flags & WQ_UNBOUND)) {
|
|
wq->cpu_pwqs = alloc_percpu(struct pool_workqueue);
|
|
if (!wq->cpu_pwqs)
|
|
return -ENOMEM;
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
struct pool_workqueue *pwq =
|
|
per_cpu_ptr(wq->cpu_pwqs, cpu);
|
|
struct worker_pool *cpu_pools =
|
|
per_cpu(cpu_worker_pools, cpu);
|
|
|
|
init_pwq(pwq, wq, &cpu_pools[highpri]);
|
|
|
|
mutex_lock(&wq->mutex);
|
|
link_pwq(pwq);
|
|
mutex_unlock(&wq->mutex);
|
|
}
|
|
return 0;
|
|
} else if (wq->flags & __WQ_ORDERED) {
|
|
ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]);
|
|
/* there should only be single pwq for ordering guarantee */
|
|
WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node ||
|
|
wq->pwqs.prev != &wq->dfl_pwq->pwqs_node),
|
|
"ordering guarantee broken for workqueue %s\n", wq->name);
|
|
return ret;
|
|
} else {
|
|
return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
|
|
}
|
|
}
|
|
|
|
static int wq_clamp_max_active(int max_active, unsigned int flags,
|
|
const char *name)
|
|
{
|
|
int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
|
|
|
|
if (max_active < 1 || max_active > lim)
|
|
pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
|
|
max_active, name, 1, lim);
|
|
|
|
return clamp_val(max_active, 1, lim);
|
|
}
|
|
|
|
struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
|
|
unsigned int flags,
|
|
int max_active,
|
|
struct lock_class_key *key,
|
|
const char *lock_name, ...)
|
|
{
|
|
size_t tbl_size = 0;
|
|
va_list args;
|
|
struct workqueue_struct *wq;
|
|
struct pool_workqueue *pwq;
|
|
|
|
/* see the comment above the definition of WQ_POWER_EFFICIENT */
|
|
if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
|
|
flags |= WQ_UNBOUND;
|
|
|
|
/* allocate wq and format name */
|
|
if (flags & WQ_UNBOUND)
|
|
tbl_size = nr_node_ids * sizeof(wq->numa_pwq_tbl[0]);
|
|
|
|
wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL);
|
|
if (!wq)
|
|
return NULL;
|
|
|
|
if (flags & WQ_UNBOUND) {
|
|
wq->unbound_attrs = alloc_workqueue_attrs(GFP_KERNEL);
|
|
if (!wq->unbound_attrs)
|
|
goto err_free_wq;
|
|
}
|
|
|
|
va_start(args, lock_name);
|
|
vsnprintf(wq->name, sizeof(wq->name), fmt, args);
|
|
va_end(args);
|
|
|
|
max_active = max_active ?: WQ_DFL_ACTIVE;
|
|
max_active = wq_clamp_max_active(max_active, flags, wq->name);
|
|
|
|
/* init wq */
|
|
wq->flags = flags;
|
|
wq->saved_max_active = max_active;
|
|
mutex_init(&wq->mutex);
|
|
atomic_set(&wq->nr_pwqs_to_flush, 0);
|
|
INIT_LIST_HEAD(&wq->pwqs);
|
|
INIT_LIST_HEAD(&wq->flusher_queue);
|
|
INIT_LIST_HEAD(&wq->flusher_overflow);
|
|
INIT_LIST_HEAD(&wq->maydays);
|
|
|
|
lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
|
|
INIT_LIST_HEAD(&wq->list);
|
|
|
|
if (alloc_and_link_pwqs(wq) < 0)
|
|
goto err_free_wq;
|
|
|
|
/*
|
|
* Workqueues which may be used during memory reclaim should
|
|
* have a rescuer to guarantee forward progress.
|
|
*/
|
|
if (flags & WQ_MEM_RECLAIM) {
|
|
struct worker *rescuer;
|
|
|
|
rescuer = alloc_worker(NUMA_NO_NODE);
|
|
if (!rescuer)
|
|
goto err_destroy;
|
|
|
|
rescuer->rescue_wq = wq;
|
|
rescuer->task = kthread_create(rescuer_thread, rescuer, "%s",
|
|
wq->name);
|
|
if (IS_ERR(rescuer->task)) {
|
|
kfree(rescuer);
|
|
goto err_destroy;
|
|
}
|
|
|
|
wq->rescuer = rescuer;
|
|
rescuer->task->flags |= PF_NO_SETAFFINITY;
|
|
wake_up_process(rescuer->task);
|
|
}
|
|
|
|
if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq))
|
|
goto err_destroy;
|
|
|
|
/*
|
|
* wq_pool_mutex protects global freeze state and workqueues list.
|
|
* Grab it, adjust max_active and add the new @wq to workqueues
|
|
* list.
|
|
*/
|
|
mutex_lock(&wq_pool_mutex);
|
|
|
|
mutex_lock(&wq->mutex);
|
|
for_each_pwq(pwq, wq)
|
|
pwq_adjust_max_active(pwq);
|
|
mutex_unlock(&wq->mutex);
|
|
|
|
list_add(&wq->list, &workqueues);
|
|
|
|
mutex_unlock(&wq_pool_mutex);
|
|
|
|
return wq;
|
|
|
|
err_free_wq:
|
|
free_workqueue_attrs(wq->unbound_attrs);
|
|
kfree(wq);
|
|
return NULL;
|
|
err_destroy:
|
|
destroy_workqueue(wq);
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
|
|
|
|
/**
|
|
* destroy_workqueue - safely terminate a workqueue
|
|
* @wq: target workqueue
|
|
*
|
|
* Safely destroy a workqueue. All work currently pending will be done first.
|
|
*/
|
|
void destroy_workqueue(struct workqueue_struct *wq)
|
|
{
|
|
struct pool_workqueue *pwq;
|
|
int node;
|
|
|
|
/* drain it before proceeding with destruction */
|
|
drain_workqueue(wq);
|
|
|
|
/* sanity checks */
|
|
mutex_lock(&wq->mutex);
|
|
for_each_pwq(pwq, wq) {
|
|
int i;
|
|
|
|
for (i = 0; i < WORK_NR_COLORS; i++) {
|
|
if (WARN_ON(pwq->nr_in_flight[i])) {
|
|
mutex_unlock(&wq->mutex);
|
|
return;
|
|
}
|
|
}
|
|
|
|
if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) ||
|
|
WARN_ON(pwq->nr_active) ||
|
|
WARN_ON(!list_empty(&pwq->delayed_works))) {
|
|
mutex_unlock(&wq->mutex);
|
|
return;
|
|
}
|
|
}
|
|
mutex_unlock(&wq->mutex);
|
|
|
|
/*
|
|
* wq list is used to freeze wq, remove from list after
|
|
* flushing is complete in case freeze races us.
|
|
*/
|
|
mutex_lock(&wq_pool_mutex);
|
|
list_del_init(&wq->list);
|
|
mutex_unlock(&wq_pool_mutex);
|
|
|
|
workqueue_sysfs_unregister(wq);
|
|
|
|
if (wq->rescuer) {
|
|
kthread_stop(wq->rescuer->task);
|
|
kfree(wq->rescuer);
|
|
wq->rescuer = NULL;
|
|
}
|
|
|
|
if (!(wq->flags & WQ_UNBOUND)) {
|
|
/*
|
|
* The base ref is never dropped on per-cpu pwqs. Directly
|
|
* free the pwqs and wq.
|
|
*/
|
|
free_percpu(wq->cpu_pwqs);
|
|
kfree(wq);
|
|
} else {
|
|
/*
|
|
* We're the sole accessor of @wq at this point. Directly
|
|
* access numa_pwq_tbl[] and dfl_pwq to put the base refs.
|
|
* @wq will be freed when the last pwq is released.
|
|
*/
|
|
for_each_node(node) {
|
|
pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
|
|
RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL);
|
|
put_pwq_unlocked(pwq);
|
|
}
|
|
|
|
/*
|
|
* Put dfl_pwq. @wq may be freed any time after dfl_pwq is
|
|
* put. Don't access it afterwards.
|
|
*/
|
|
pwq = wq->dfl_pwq;
|
|
wq->dfl_pwq = NULL;
|
|
put_pwq_unlocked(pwq);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(destroy_workqueue);
|
|
|
|
/**
|
|
* workqueue_set_max_active - adjust max_active of a workqueue
|
|
* @wq: target workqueue
|
|
* @max_active: new max_active value.
|
|
*
|
|
* Set max_active of @wq to @max_active.
|
|
*
|
|
* CONTEXT:
|
|
* Don't call from IRQ context.
|
|
*/
|
|
void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
|
|
{
|
|
struct pool_workqueue *pwq;
|
|
|
|
/* disallow meddling with max_active for ordered workqueues */
|
|
if (WARN_ON(wq->flags & __WQ_ORDERED))
|
|
return;
|
|
|
|
max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
|
|
|
|
mutex_lock(&wq->mutex);
|
|
|
|
wq->saved_max_active = max_active;
|
|
|
|
for_each_pwq(pwq, wq)
|
|
pwq_adjust_max_active(pwq);
|
|
|
|
mutex_unlock(&wq->mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(workqueue_set_max_active);
|
|
|
|
/**
|
|
* current_is_workqueue_rescuer - is %current workqueue rescuer?
|
|
*
|
|
* Determine whether %current is a workqueue rescuer. Can be used from
|
|
* work functions to determine whether it's being run off the rescuer task.
|
|
*
|
|
* Return: %true if %current is a workqueue rescuer. %false otherwise.
|
|
*/
|
|
bool current_is_workqueue_rescuer(void)
|
|
{
|
|
struct worker *worker = current_wq_worker();
|
|
|
|
return worker && worker->rescue_wq;
|
|
}
|
|
|
|
/**
|
|
* workqueue_congested - test whether a workqueue is congested
|
|
* @cpu: CPU in question
|
|
* @wq: target workqueue
|
|
*
|
|
* Test whether @wq's cpu workqueue for @cpu is congested. There is
|
|
* no synchronization around this function and the test result is
|
|
* unreliable and only useful as advisory hints or for debugging.
|
|
*
|
|
* If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU.
|
|
* Note that both per-cpu and unbound workqueues may be associated with
|
|
* multiple pool_workqueues which have separate congested states. A
|
|
* workqueue being congested on one CPU doesn't mean the workqueue is also
|
|
* contested on other CPUs / NUMA nodes.
|
|
*
|
|
* Return:
|
|
* %true if congested, %false otherwise.
|
|
*/
|
|
bool workqueue_congested(int cpu, struct workqueue_struct *wq)
|
|
{
|
|
struct pool_workqueue *pwq;
|
|
bool ret;
|
|
|
|
rcu_read_lock_sched();
|
|
|
|
if (cpu == WORK_CPU_UNBOUND)
|
|
cpu = smp_processor_id();
|
|
|
|
if (!(wq->flags & WQ_UNBOUND))
|
|
pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
|
|
else
|
|
pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
|
|
|
|
ret = !list_empty(&pwq->delayed_works);
|
|
rcu_read_unlock_sched();
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(workqueue_congested);
|
|
|
|
/**
|
|
* work_busy - test whether a work is currently pending or running
|
|
* @work: the work to be tested
|
|
*
|
|
* Test whether @work is currently pending or running. There is no
|
|
* synchronization around this function and the test result is
|
|
* unreliable and only useful as advisory hints or for debugging.
|
|
*
|
|
* Return:
|
|
* OR'd bitmask of WORK_BUSY_* bits.
|
|
*/
|
|
unsigned int work_busy(struct work_struct *work)
|
|
{
|
|
struct worker_pool *pool;
|
|
unsigned long flags;
|
|
unsigned int ret = 0;
|
|
|
|
if (work_pending(work))
|
|
ret |= WORK_BUSY_PENDING;
|
|
|
|
local_irq_save(flags);
|
|
pool = get_work_pool(work);
|
|
if (pool) {
|
|
spin_lock(&pool->lock);
|
|
if (find_worker_executing_work(pool, work))
|
|
ret |= WORK_BUSY_RUNNING;
|
|
spin_unlock(&pool->lock);
|
|
}
|
|
local_irq_restore(flags);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(work_busy);
|
|
|
|
/**
|
|
* set_worker_desc - set description for the current work item
|
|
* @fmt: printf-style format string
|
|
* @...: arguments for the format string
|
|
*
|
|
* This function can be called by a running work function to describe what
|
|
* the work item is about. If the worker task gets dumped, this
|
|
* information will be printed out together to help debugging. The
|
|
* description can be at most WORKER_DESC_LEN including the trailing '\0'.
|
|
*/
|
|
void set_worker_desc(const char *fmt, ...)
|
|
{
|
|
struct worker *worker = current_wq_worker();
|
|
va_list args;
|
|
|
|
if (worker) {
|
|
va_start(args, fmt);
|
|
vsnprintf(worker->desc, sizeof(worker->desc), fmt, args);
|
|
va_end(args);
|
|
worker->desc_valid = true;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* print_worker_info - print out worker information and description
|
|
* @log_lvl: the log level to use when printing
|
|
* @task: target task
|
|
*
|
|
* If @task is a worker and currently executing a work item, print out the
|
|
* name of the workqueue being serviced and worker description set with
|
|
* set_worker_desc() by the currently executing work item.
|
|
*
|
|
* This function can be safely called on any task as long as the
|
|
* task_struct itself is accessible. While safe, this function isn't
|
|
* synchronized and may print out mixups or garbages of limited length.
|
|
*/
|
|
void print_worker_info(const char *log_lvl, struct task_struct *task)
|
|
{
|
|
work_func_t *fn = NULL;
|
|
char name[WQ_NAME_LEN] = { };
|
|
char desc[WORKER_DESC_LEN] = { };
|
|
struct pool_workqueue *pwq = NULL;
|
|
struct workqueue_struct *wq = NULL;
|
|
bool desc_valid = false;
|
|
struct worker *worker;
|
|
|
|
if (!(task->flags & PF_WQ_WORKER))
|
|
return;
|
|
|
|
/*
|
|
* This function is called without any synchronization and @task
|
|
* could be in any state. Be careful with dereferences.
|
|
*/
|
|
worker = probe_kthread_data(task);
|
|
|
|
/*
|
|
* Carefully copy the associated workqueue's workfn and name. Keep
|
|
* the original last '\0' in case the original contains garbage.
|
|
*/
|
|
probe_kernel_read(&fn, &worker->current_func, sizeof(fn));
|
|
probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq));
|
|
probe_kernel_read(&wq, &pwq->wq, sizeof(wq));
|
|
probe_kernel_read(name, wq->name, sizeof(name) - 1);
|
|
|
|
/* copy worker description */
|
|
probe_kernel_read(&desc_valid, &worker->desc_valid, sizeof(desc_valid));
|
|
if (desc_valid)
|
|
probe_kernel_read(desc, worker->desc, sizeof(desc) - 1);
|
|
|
|
if (fn || name[0] || desc[0]) {
|
|
printk("%sWorkqueue: %s %pf", log_lvl, name, fn);
|
|
if (desc[0])
|
|
pr_cont(" (%s)", desc);
|
|
pr_cont("\n");
|
|
}
|
|
}
|
|
|
|
/*
|
|
* CPU hotplug.
|
|
*
|
|
* There are two challenges in supporting CPU hotplug. Firstly, there
|
|
* are a lot of assumptions on strong associations among work, pwq and
|
|
* pool which make migrating pending and scheduled works very
|
|
* difficult to implement without impacting hot paths. Secondly,
|
|
* worker pools serve mix of short, long and very long running works making
|
|
* blocked draining impractical.
|
|
*
|
|
* This is solved by allowing the pools to be disassociated from the CPU
|
|
* running as an unbound one and allowing it to be reattached later if the
|
|
* cpu comes back online.
|
|
*/
|
|
|
|
static void wq_unbind_fn(struct work_struct *work)
|
|
{
|
|
int cpu = smp_processor_id();
|
|
struct worker_pool *pool;
|
|
struct worker *worker;
|
|
|
|
for_each_cpu_worker_pool(pool, cpu) {
|
|
mutex_lock(&pool->attach_mutex);
|
|
spin_lock_irq(&pool->lock);
|
|
|
|
/*
|
|
* We've blocked all attach/detach operations. Make all workers
|
|
* unbound and set DISASSOCIATED. Before this, all workers
|
|
* except for the ones which are still executing works from
|
|
* before the last CPU down must be on the cpu. After
|
|
* this, they may become diasporas.
|
|
*/
|
|
for_each_pool_worker(worker, pool)
|
|
worker->flags |= WORKER_UNBOUND;
|
|
|
|
pool->flags |= POOL_DISASSOCIATED;
|
|
|
|
spin_unlock_irq(&pool->lock);
|
|
mutex_unlock(&pool->attach_mutex);
|
|
|
|
/*
|
|
* Call schedule() so that we cross rq->lock and thus can
|
|
* guarantee sched callbacks see the %WORKER_UNBOUND flag.
|
|
* This is necessary as scheduler callbacks may be invoked
|
|
* from other cpus.
|
|
*/
|
|
schedule();
|
|
|
|
/*
|
|
* Sched callbacks are disabled now. Zap nr_running.
|
|
* After this, nr_running stays zero and need_more_worker()
|
|
* and keep_working() are always true as long as the
|
|
* worklist is not empty. This pool now behaves as an
|
|
* unbound (in terms of concurrency management) pool which
|
|
* are served by workers tied to the pool.
|
|
*/
|
|
atomic_set(&pool->nr_running, 0);
|
|
|
|
/*
|
|
* With concurrency management just turned off, a busy
|
|
* worker blocking could lead to lengthy stalls. Kick off
|
|
* unbound chain execution of currently pending work items.
|
|
*/
|
|
spin_lock_irq(&pool->lock);
|
|
wake_up_worker(pool);
|
|
spin_unlock_irq(&pool->lock);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* rebind_workers - rebind all workers of a pool to the associated CPU
|
|
* @pool: pool of interest
|
|
*
|
|
* @pool->cpu is coming online. Rebind all workers to the CPU.
|
|
*/
|
|
static void rebind_workers(struct worker_pool *pool)
|
|
{
|
|
struct worker *worker;
|
|
|
|
lockdep_assert_held(&pool->attach_mutex);
|
|
|
|
/*
|
|
* Restore CPU affinity of all workers. As all idle workers should
|
|
* be on the run-queue of the associated CPU before any local
|
|
* wake-ups for concurrency management happen, restore CPU affinty
|
|
* of all workers first and then clear UNBOUND. As we're called
|
|
* from CPU_ONLINE, the following shouldn't fail.
|
|
*/
|
|
for_each_pool_worker(worker, pool)
|
|
WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
|
|
pool->attrs->cpumask) < 0);
|
|
|
|
spin_lock_irq(&pool->lock);
|
|
pool->flags &= ~POOL_DISASSOCIATED;
|
|
|
|
for_each_pool_worker(worker, pool) {
|
|
unsigned int worker_flags = worker->flags;
|
|
|
|
/*
|
|
* A bound idle worker should actually be on the runqueue
|
|
* of the associated CPU for local wake-ups targeting it to
|
|
* work. Kick all idle workers so that they migrate to the
|
|
* associated CPU. Doing this in the same loop as
|
|
* replacing UNBOUND with REBOUND is safe as no worker will
|
|
* be bound before @pool->lock is released.
|
|
*/
|
|
if (worker_flags & WORKER_IDLE)
|
|
wake_up_process(worker->task);
|
|
|
|
/*
|
|
* We want to clear UNBOUND but can't directly call
|
|
* worker_clr_flags() or adjust nr_running. Atomically
|
|
* replace UNBOUND with another NOT_RUNNING flag REBOUND.
|
|
* @worker will clear REBOUND using worker_clr_flags() when
|
|
* it initiates the next execution cycle thus restoring
|
|
* concurrency management. Note that when or whether
|
|
* @worker clears REBOUND doesn't affect correctness.
|
|
*
|
|
* ACCESS_ONCE() is necessary because @worker->flags may be
|
|
* tested without holding any lock in
|
|
* wq_worker_waking_up(). Without it, NOT_RUNNING test may
|
|
* fail incorrectly leading to premature concurrency
|
|
* management operations.
|
|
*/
|
|
WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND));
|
|
worker_flags |= WORKER_REBOUND;
|
|
worker_flags &= ~WORKER_UNBOUND;
|
|
ACCESS_ONCE(worker->flags) = worker_flags;
|
|
}
|
|
|
|
spin_unlock_irq(&pool->lock);
|
|
}
|
|
|
|
/**
|
|
* restore_unbound_workers_cpumask - restore cpumask of unbound workers
|
|
* @pool: unbound pool of interest
|
|
* @cpu: the CPU which is coming up
|
|
*
|
|
* An unbound pool may end up with a cpumask which doesn't have any online
|
|
* CPUs. When a worker of such pool get scheduled, the scheduler resets
|
|
* its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any
|
|
* online CPU before, cpus_allowed of all its workers should be restored.
|
|
*/
|
|
static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
|
|
{
|
|
static cpumask_t cpumask;
|
|
struct worker *worker;
|
|
|
|
lockdep_assert_held(&pool->attach_mutex);
|
|
|
|
/* is @cpu allowed for @pool? */
|
|
if (!cpumask_test_cpu(cpu, pool->attrs->cpumask))
|
|
return;
|
|
|
|
/* is @cpu the only online CPU? */
|
|
cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask);
|
|
if (cpumask_weight(&cpumask) != 1)
|
|
return;
|
|
|
|
/* as we're called from CPU_ONLINE, the following shouldn't fail */
|
|
for_each_pool_worker(worker, pool)
|
|
WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
|
|
pool->attrs->cpumask) < 0);
|
|
}
|
|
|
|
/*
|
|
* Workqueues should be brought up before normal priority CPU notifiers.
|
|
* This will be registered high priority CPU notifier.
|
|
*/
|
|
static int workqueue_cpu_up_callback(struct notifier_block *nfb,
|
|
unsigned long action,
|
|
void *hcpu)
|
|
{
|
|
int cpu = (unsigned long)hcpu;
|
|
struct worker_pool *pool;
|
|
struct workqueue_struct *wq;
|
|
int pi;
|
|
|
|
switch (action & ~CPU_TASKS_FROZEN) {
|
|
case CPU_UP_PREPARE:
|
|
for_each_cpu_worker_pool(pool, cpu) {
|
|
if (pool->nr_workers)
|
|
continue;
|
|
if (!create_worker(pool))
|
|
return NOTIFY_BAD;
|
|
}
|
|
break;
|
|
|
|
case CPU_DOWN_FAILED:
|
|
case CPU_ONLINE:
|
|
mutex_lock(&wq_pool_mutex);
|
|
|
|
for_each_pool(pool, pi) {
|
|
mutex_lock(&pool->attach_mutex);
|
|
|
|
if (pool->cpu == cpu)
|
|
rebind_workers(pool);
|
|
else if (pool->cpu < 0)
|
|
restore_unbound_workers_cpumask(pool, cpu);
|
|
|
|
mutex_unlock(&pool->attach_mutex);
|
|
}
|
|
|
|
/* update NUMA affinity of unbound workqueues */
|
|
list_for_each_entry(wq, &workqueues, list)
|
|
wq_update_unbound_numa(wq, cpu, true);
|
|
|
|
mutex_unlock(&wq_pool_mutex);
|
|
break;
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
/*
|
|
* Workqueues should be brought down after normal priority CPU notifiers.
|
|
* This will be registered as low priority CPU notifier.
|
|
*/
|
|
static int workqueue_cpu_down_callback(struct notifier_block *nfb,
|
|
unsigned long action,
|
|
void *hcpu)
|
|
{
|
|
int cpu = (unsigned long)hcpu;
|
|
struct work_struct unbind_work;
|
|
struct workqueue_struct *wq;
|
|
|
|
switch (action & ~CPU_TASKS_FROZEN) {
|
|
case CPU_DOWN_PREPARE:
|
|
/* unbinding per-cpu workers should happen on the local CPU */
|
|
INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn);
|
|
queue_work_on(cpu, system_highpri_wq, &unbind_work);
|
|
|
|
/* update NUMA affinity of unbound workqueues */
|
|
mutex_lock(&wq_pool_mutex);
|
|
list_for_each_entry(wq, &workqueues, list)
|
|
wq_update_unbound_numa(wq, cpu, false);
|
|
mutex_unlock(&wq_pool_mutex);
|
|
|
|
/* wait for per-cpu unbinding to finish */
|
|
flush_work(&unbind_work);
|
|
destroy_work_on_stack(&unbind_work);
|
|
break;
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
struct work_for_cpu {
|
|
struct work_struct work;
|
|
long (*fn)(void *);
|
|
void *arg;
|
|
long ret;
|
|
};
|
|
|
|
static void work_for_cpu_fn(struct work_struct *work)
|
|
{
|
|
struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work);
|
|
|
|
wfc->ret = wfc->fn(wfc->arg);
|
|
}
|
|
|
|
/**
|
|
* work_on_cpu - run a function in user context on a particular cpu
|
|
* @cpu: the cpu to run on
|
|
* @fn: the function to run
|
|
* @arg: the function arg
|
|
*
|
|
* It is up to the caller to ensure that the cpu doesn't go offline.
|
|
* The caller must not hold any locks which would prevent @fn from completing.
|
|
*
|
|
* Return: The value @fn returns.
|
|
*/
|
|
long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
|
|
{
|
|
struct work_for_cpu wfc = { .fn = fn, .arg = arg };
|
|
|
|
INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
|
|
schedule_work_on(cpu, &wfc.work);
|
|
flush_work(&wfc.work);
|
|
destroy_work_on_stack(&wfc.work);
|
|
return wfc.ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(work_on_cpu);
|
|
#endif /* CONFIG_SMP */
|
|
|
|
#ifdef CONFIG_FREEZER
|
|
|
|
/**
|
|
* freeze_workqueues_begin - begin freezing workqueues
|
|
*
|
|
* Start freezing workqueues. After this function returns, all freezable
|
|
* workqueues will queue new works to their delayed_works list instead of
|
|
* pool->worklist.
|
|
*
|
|
* CONTEXT:
|
|
* Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
|
|
*/
|
|
void freeze_workqueues_begin(void)
|
|
{
|
|
struct workqueue_struct *wq;
|
|
struct pool_workqueue *pwq;
|
|
|
|
mutex_lock(&wq_pool_mutex);
|
|
|
|
WARN_ON_ONCE(workqueue_freezing);
|
|
workqueue_freezing = true;
|
|
|
|
list_for_each_entry(wq, &workqueues, list) {
|
|
mutex_lock(&wq->mutex);
|
|
for_each_pwq(pwq, wq)
|
|
pwq_adjust_max_active(pwq);
|
|
mutex_unlock(&wq->mutex);
|
|
}
|
|
|
|
mutex_unlock(&wq_pool_mutex);
|
|
}
|
|
|
|
/**
|
|
* freeze_workqueues_busy - are freezable workqueues still busy?
|
|
*
|
|
* Check whether freezing is complete. This function must be called
|
|
* between freeze_workqueues_begin() and thaw_workqueues().
|
|
*
|
|
* CONTEXT:
|
|
* Grabs and releases wq_pool_mutex.
|
|
*
|
|
* Return:
|
|
* %true if some freezable workqueues are still busy. %false if freezing
|
|
* is complete.
|
|
*/
|
|
bool freeze_workqueues_busy(void)
|
|
{
|
|
bool busy = false;
|
|
struct workqueue_struct *wq;
|
|
struct pool_workqueue *pwq;
|
|
|
|
mutex_lock(&wq_pool_mutex);
|
|
|
|
WARN_ON_ONCE(!workqueue_freezing);
|
|
|
|
list_for_each_entry(wq, &workqueues, list) {
|
|
if (!(wq->flags & WQ_FREEZABLE))
|
|
continue;
|
|
/*
|
|
* nr_active is monotonically decreasing. It's safe
|
|
* to peek without lock.
|
|
*/
|
|
rcu_read_lock_sched();
|
|
for_each_pwq(pwq, wq) {
|
|
WARN_ON_ONCE(pwq->nr_active < 0);
|
|
if (pwq->nr_active) {
|
|
busy = true;
|
|
rcu_read_unlock_sched();
|
|
goto out_unlock;
|
|
}
|
|
}
|
|
rcu_read_unlock_sched();
|
|
}
|
|
out_unlock:
|
|
mutex_unlock(&wq_pool_mutex);
|
|
return busy;
|
|
}
|
|
|
|
/**
|
|
* thaw_workqueues - thaw workqueues
|
|
*
|
|
* Thaw workqueues. Normal queueing is restored and all collected
|
|
* frozen works are transferred to their respective pool worklists.
|
|
*
|
|
* CONTEXT:
|
|
* Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
|
|
*/
|
|
void thaw_workqueues(void)
|
|
{
|
|
struct workqueue_struct *wq;
|
|
struct pool_workqueue *pwq;
|
|
|
|
mutex_lock(&wq_pool_mutex);
|
|
|
|
if (!workqueue_freezing)
|
|
goto out_unlock;
|
|
|
|
workqueue_freezing = false;
|
|
|
|
/* restore max_active and repopulate worklist */
|
|
list_for_each_entry(wq, &workqueues, list) {
|
|
mutex_lock(&wq->mutex);
|
|
for_each_pwq(pwq, wq)
|
|
pwq_adjust_max_active(pwq);
|
|
mutex_unlock(&wq->mutex);
|
|
}
|
|
|
|
out_unlock:
|
|
mutex_unlock(&wq_pool_mutex);
|
|
}
|
|
#endif /* CONFIG_FREEZER */
|
|
|
|
static void __init wq_numa_init(void)
|
|
{
|
|
cpumask_var_t *tbl;
|
|
int node, cpu;
|
|
|
|
if (num_possible_nodes() <= 1)
|
|
return;
|
|
|
|
if (wq_disable_numa) {
|
|
pr_info("workqueue: NUMA affinity support disabled\n");
|
|
return;
|
|
}
|
|
|
|
wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(GFP_KERNEL);
|
|
BUG_ON(!wq_update_unbound_numa_attrs_buf);
|
|
|
|
/*
|
|
* We want masks of possible CPUs of each node which isn't readily
|
|
* available. Build one from cpu_to_node() which should have been
|
|
* fully initialized by now.
|
|
*/
|
|
tbl = kzalloc(nr_node_ids * sizeof(tbl[0]), GFP_KERNEL);
|
|
BUG_ON(!tbl);
|
|
|
|
for_each_node(node)
|
|
BUG_ON(!zalloc_cpumask_var_node(&tbl[node], GFP_KERNEL,
|
|
node_online(node) ? node : NUMA_NO_NODE));
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
node = cpu_to_node(cpu);
|
|
if (WARN_ON(node == NUMA_NO_NODE)) {
|
|
pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu);
|
|
/* happens iff arch is bonkers, let's just proceed */
|
|
return;
|
|
}
|
|
cpumask_set_cpu(cpu, tbl[node]);
|
|
}
|
|
|
|
wq_numa_possible_cpumask = tbl;
|
|
wq_numa_enabled = true;
|
|
}
|
|
|
|
static int __init init_workqueues(void)
|
|
{
|
|
int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL };
|
|
int i, cpu;
|
|
|
|
WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
|
|
|
|
pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);
|
|
|
|
cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP);
|
|
hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN);
|
|
|
|
wq_numa_init();
|
|
|
|
/* initialize CPU pools */
|
|
for_each_possible_cpu(cpu) {
|
|
struct worker_pool *pool;
|
|
|
|
i = 0;
|
|
for_each_cpu_worker_pool(pool, cpu) {
|
|
BUG_ON(init_worker_pool(pool));
|
|
pool->cpu = cpu;
|
|
cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu));
|
|
pool->attrs->nice = std_nice[i++];
|
|
pool->node = cpu_to_node(cpu);
|
|
|
|
/* alloc pool ID */
|
|
mutex_lock(&wq_pool_mutex);
|
|
BUG_ON(worker_pool_assign_id(pool));
|
|
mutex_unlock(&wq_pool_mutex);
|
|
}
|
|
}
|
|
|
|
/* create the initial worker */
|
|
for_each_online_cpu(cpu) {
|
|
struct worker_pool *pool;
|
|
|
|
for_each_cpu_worker_pool(pool, cpu) {
|
|
pool->flags &= ~POOL_DISASSOCIATED;
|
|
BUG_ON(!create_worker(pool));
|
|
}
|
|
}
|
|
|
|
/* create default unbound and ordered wq attrs */
|
|
for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
|
|
struct workqueue_attrs *attrs;
|
|
|
|
BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
|
|
attrs->nice = std_nice[i];
|
|
unbound_std_wq_attrs[i] = attrs;
|
|
|
|
/*
|
|
* An ordered wq should have only one pwq as ordering is
|
|
* guaranteed by max_active which is enforced by pwqs.
|
|
* Turn off NUMA so that dfl_pwq is used for all nodes.
|
|
*/
|
|
BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
|
|
attrs->nice = std_nice[i];
|
|
attrs->no_numa = true;
|
|
ordered_wq_attrs[i] = attrs;
|
|
}
|
|
|
|
system_wq = alloc_workqueue("events", 0, 0);
|
|
system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0);
|
|
system_long_wq = alloc_workqueue("events_long", 0, 0);
|
|
system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
|
|
WQ_UNBOUND_MAX_ACTIVE);
|
|
system_freezable_wq = alloc_workqueue("events_freezable",
|
|
WQ_FREEZABLE, 0);
|
|
system_power_efficient_wq = alloc_workqueue("events_power_efficient",
|
|
WQ_POWER_EFFICIENT, 0);
|
|
system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient",
|
|
WQ_FREEZABLE | WQ_POWER_EFFICIENT,
|
|
0);
|
|
BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq ||
|
|
!system_unbound_wq || !system_freezable_wq ||
|
|
!system_power_efficient_wq ||
|
|
!system_freezable_power_efficient_wq);
|
|
return 0;
|
|
}
|
|
early_initcall(init_workqueues);
|