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![Tejun Heo](/assets/img/avatar_default.png)
25511a4776
"workqueue: reimplement CPU online rebinding to handle idle
workers" added CPU locality sanity check in process_one_work(). It
triggers if a worker is executing on a different CPU without UNBOUND
or REBIND set.
This works for all normal workers but rescuers can trigger this
spuriously when they're serving the unbound or a disassociated
global_cwq - rescuers don't have either flag set and thus its
gcwq->cpu can be a different value including %WORK_CPU_UNBOUND.
Fix it by additionally testing %GCWQ_DISASSOCIATED.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
LKML-Refence: <20120721213656.GA7783@linux.vnet.ibm.com>
3762 lines
102 KiB
C
3762 lines
102 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 is one worker pool for each CPU and
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* one extra for works which are better served by workers which are
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* not bound to any specific CPU.
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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 "workqueue_sched.h"
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enum {
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/*
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* global_cwq flags
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*
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* A bound gcwq 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 gcwq behaves as an unbound one.
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*
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* Note that DISASSOCIATED can be flipped only while holding
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* managership of all pools on the gcwq to avoid changing binding
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* state while create_worker() is in progress.
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*/
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GCWQ_DISASSOCIATED = 1 << 0, /* cpu can't serve workers */
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GCWQ_FREEZING = 1 << 1, /* freeze in progress */
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/* pool flags */
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POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */
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/* worker flags */
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WORKER_STARTED = 1 << 0, /* started */
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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_REBIND = 1 << 5, /* mom is home, come back */
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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_NOT_RUNNING = WORKER_PREP | WORKER_REBIND | WORKER_UNBOUND |
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WORKER_CPU_INTENSIVE,
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NR_WORKER_POOLS = 2, /* # worker pools per gcwq */
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BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
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BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER,
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BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1,
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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 -20.
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*/
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RESCUER_NICE_LEVEL = -20,
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HIGHPRI_NICE_LEVEL = -20,
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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: gcwq->lock protected. Access with gcwq->lock held.
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*
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* X: During normal operation, modification requires gcwq->lock and
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* should be done only from local cpu. Either disabling preemption
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* on local cpu or grabbing gcwq->lock is enough for read access.
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* If GCWQ_DISASSOCIATED is set, it's identical to L.
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*
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* F: wq->flush_mutex protected.
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*
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* W: workqueue_lock protected.
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*/
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struct global_cwq;
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struct worker_pool;
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struct idle_rebind;
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/*
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* The poor guys doing the actual heavy lifting. All on-duty workers
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* are either serving the manager role, on idle list or on busy hash.
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*/
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struct worker {
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/* on idle list while idle, on busy hash table while busy */
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union {
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struct list_head entry; /* L: while idle */
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struct hlist_node hentry; /* L: while busy */
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};
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struct work_struct *current_work; /* L: work being processed */
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struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */
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struct list_head scheduled; /* L: scheduled works */
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struct task_struct *task; /* I: worker task */
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struct worker_pool *pool; /* I: the associated pool */
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/* 64 bytes boundary on 64bit, 32 on 32bit */
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unsigned long last_active; /* L: last active timestamp */
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unsigned int flags; /* X: flags */
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int id; /* I: worker id */
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/* for rebinding worker to CPU */
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struct idle_rebind *idle_rebind; /* L: for idle worker */
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struct work_struct rebind_work; /* L: for busy worker */
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};
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struct worker_pool {
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struct global_cwq *gcwq; /* I: the owning gcwq */
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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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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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struct mutex manager_mutex; /* mutex manager should hold */
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struct ida worker_ida; /* L: for worker IDs */
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};
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/*
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* Global per-cpu workqueue. There's one and only one for each cpu
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* and all works are queued and processed here regardless of their
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* target workqueues.
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*/
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struct global_cwq {
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spinlock_t lock; /* the gcwq lock */
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unsigned int cpu; /* I: the associated cpu */
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unsigned int flags; /* L: GCWQ_* flags */
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/* workers are chained either in busy_hash or pool idle_list */
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struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE];
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/* L: hash of busy workers */
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struct worker_pool pools[2]; /* normal and highpri pools */
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wait_queue_head_t rebind_hold; /* rebind hold wait */
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} ____cacheline_aligned_in_smp;
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/*
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* The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of
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* work_struct->data are used for flags and thus cwqs need to be
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* aligned at two's power of the number of flag bits.
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*/
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struct cpu_workqueue_struct {
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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 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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};
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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; /* F: list of flushers */
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int flush_color; /* F: flush color waiting for */
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struct completion done; /* flush completion */
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};
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/*
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* All cpumasks are assumed to be always set on UP and thus can't be
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* used to determine whether there's something to be done.
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*/
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#ifdef CONFIG_SMP
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typedef cpumask_var_t mayday_mask_t;
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#define mayday_test_and_set_cpu(cpu, mask) \
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cpumask_test_and_set_cpu((cpu), (mask))
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#define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask))
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#define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask))
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#define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp))
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#define free_mayday_mask(mask) free_cpumask_var((mask))
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#else
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typedef unsigned long mayday_mask_t;
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#define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask))
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#define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask))
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#define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask))
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#define alloc_mayday_mask(maskp, gfp) true
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#define free_mayday_mask(mask) do { } while (0)
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#endif
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/*
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* The externally visible workqueue abstraction is an array of
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* per-CPU workqueues:
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*/
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struct workqueue_struct {
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unsigned int flags; /* W: WQ_* flags */
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union {
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struct cpu_workqueue_struct __percpu *pcpu;
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struct cpu_workqueue_struct *single;
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unsigned long v;
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} cpu_wq; /* I: cwq's */
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struct list_head list; /* W: list of all workqueues */
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struct mutex flush_mutex; /* protects wq flushing */
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int work_color; /* F: current work color */
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int flush_color; /* F: current flush color */
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atomic_t nr_cwqs_to_flush; /* flush in progress */
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struct wq_flusher *first_flusher; /* F: first flusher */
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struct list_head flusher_queue; /* F: flush waiters */
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struct list_head flusher_overflow; /* F: flush overflow list */
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mayday_mask_t mayday_mask; /* cpus requesting rescue */
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struct worker *rescuer; /* I: rescue worker */
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int nr_drainers; /* W: drain in progress */
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int saved_max_active; /* W: saved cwq max_active */
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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[]; /* I: workqueue name */
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};
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struct workqueue_struct *system_wq __read_mostly;
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struct workqueue_struct *system_long_wq __read_mostly;
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struct workqueue_struct *system_nrt_wq __read_mostly;
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struct workqueue_struct *system_unbound_wq __read_mostly;
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struct workqueue_struct *system_freezable_wq __read_mostly;
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struct workqueue_struct *system_nrt_freezable_wq __read_mostly;
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EXPORT_SYMBOL_GPL(system_wq);
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EXPORT_SYMBOL_GPL(system_long_wq);
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EXPORT_SYMBOL_GPL(system_nrt_wq);
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EXPORT_SYMBOL_GPL(system_unbound_wq);
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EXPORT_SYMBOL_GPL(system_freezable_wq);
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EXPORT_SYMBOL_GPL(system_nrt_freezable_wq);
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#define CREATE_TRACE_POINTS
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#include <trace/events/workqueue.h>
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#define for_each_worker_pool(pool, gcwq) \
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for ((pool) = &(gcwq)->pools[0]; \
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(pool) < &(gcwq)->pools[NR_WORKER_POOLS]; (pool)++)
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#define for_each_busy_worker(worker, i, pos, gcwq) \
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for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \
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hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)
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static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask,
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unsigned int sw)
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{
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if (cpu < nr_cpu_ids) {
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if (sw & 1) {
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cpu = cpumask_next(cpu, mask);
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if (cpu < nr_cpu_ids)
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return cpu;
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}
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if (sw & 2)
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return WORK_CPU_UNBOUND;
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}
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return WORK_CPU_NONE;
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}
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static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
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struct workqueue_struct *wq)
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{
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return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2);
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}
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/*
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* CPU iterators
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*
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* An extra gcwq is defined for an invalid cpu number
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* (WORK_CPU_UNBOUND) to host workqueues which are not bound to any
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* specific CPU. The following iterators are similar to
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* for_each_*_cpu() iterators but also considers the unbound gcwq.
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*
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* for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND
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* for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND
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* for_each_cwq_cpu() : possible CPUs for bound workqueues,
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* WORK_CPU_UNBOUND for unbound workqueues
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*/
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#define for_each_gcwq_cpu(cpu) \
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for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \
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(cpu) < WORK_CPU_NONE; \
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(cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3))
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#define for_each_online_gcwq_cpu(cpu) \
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for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \
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(cpu) < WORK_CPU_NONE; \
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(cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3))
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#define for_each_cwq_cpu(cpu, wq) \
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for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \
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(cpu) < WORK_CPU_NONE; \
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(cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq)))
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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)
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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_free(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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static struct debug_obj_descr work_debug_descr = {
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.name = "work_struct",
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.debug_hint = work_debug_hint,
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.fixup_init = work_fixup_init,
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.fixup_activate = work_fixup_activate,
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.fixup_free = work_fixup_free,
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};
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static inline void debug_work_activate(struct work_struct *work)
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{
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debug_object_activate(work, &work_debug_descr);
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}
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static inline void debug_work_deactivate(struct work_struct *work)
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{
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debug_object_deactivate(work, &work_debug_descr);
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}
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void __init_work(struct work_struct *work, int onstack)
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{
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if (onstack)
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debug_object_init_on_stack(work, &work_debug_descr);
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else
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debug_object_init(work, &work_debug_descr);
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}
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EXPORT_SYMBOL_GPL(__init_work);
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void destroy_work_on_stack(struct work_struct *work)
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{
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debug_object_free(work, &work_debug_descr);
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}
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EXPORT_SYMBOL_GPL(destroy_work_on_stack);
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#else
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static inline void debug_work_activate(struct work_struct *work) { }
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static inline void debug_work_deactivate(struct work_struct *work) { }
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#endif
|
|
|
|
/* Serializes the accesses to the list of workqueues. */
|
|
static DEFINE_SPINLOCK(workqueue_lock);
|
|
static LIST_HEAD(workqueues);
|
|
static bool workqueue_freezing; /* W: have wqs started freezing? */
|
|
|
|
/*
|
|
* The almighty global cpu workqueues. nr_running is the only field
|
|
* which is expected to be used frequently by other cpus via
|
|
* try_to_wake_up(). Put it in a separate cacheline.
|
|
*/
|
|
static DEFINE_PER_CPU(struct global_cwq, global_cwq);
|
|
static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, pool_nr_running[NR_WORKER_POOLS]);
|
|
|
|
/*
|
|
* Global cpu workqueue and nr_running counter for unbound gcwq. The
|
|
* gcwq is always online, has GCWQ_DISASSOCIATED set, and all its
|
|
* workers have WORKER_UNBOUND set.
|
|
*/
|
|
static struct global_cwq unbound_global_cwq;
|
|
static atomic_t unbound_pool_nr_running[NR_WORKER_POOLS] = {
|
|
[0 ... NR_WORKER_POOLS - 1] = ATOMIC_INIT(0), /* always 0 */
|
|
};
|
|
|
|
static int worker_thread(void *__worker);
|
|
|
|
static int worker_pool_pri(struct worker_pool *pool)
|
|
{
|
|
return pool - pool->gcwq->pools;
|
|
}
|
|
|
|
static struct global_cwq *get_gcwq(unsigned int cpu)
|
|
{
|
|
if (cpu != WORK_CPU_UNBOUND)
|
|
return &per_cpu(global_cwq, cpu);
|
|
else
|
|
return &unbound_global_cwq;
|
|
}
|
|
|
|
static atomic_t *get_pool_nr_running(struct worker_pool *pool)
|
|
{
|
|
int cpu = pool->gcwq->cpu;
|
|
int idx = worker_pool_pri(pool);
|
|
|
|
if (cpu != WORK_CPU_UNBOUND)
|
|
return &per_cpu(pool_nr_running, cpu)[idx];
|
|
else
|
|
return &unbound_pool_nr_running[idx];
|
|
}
|
|
|
|
static struct cpu_workqueue_struct *get_cwq(unsigned int cpu,
|
|
struct workqueue_struct *wq)
|
|
{
|
|
if (!(wq->flags & WQ_UNBOUND)) {
|
|
if (likely(cpu < nr_cpu_ids))
|
|
return per_cpu_ptr(wq->cpu_wq.pcpu, cpu);
|
|
} else if (likely(cpu == WORK_CPU_UNBOUND))
|
|
return wq->cpu_wq.single;
|
|
return NULL;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* A work's data points to the cwq with WORK_STRUCT_CWQ set while the
|
|
* work is on queue. Once execution starts, WORK_STRUCT_CWQ is
|
|
* cleared and the work data contains the cpu number it was last on.
|
|
*
|
|
* set_work_{cwq|cpu}() and clear_work_data() can be used to set the
|
|
* cwq, cpu or clear work->data. These functions should only be
|
|
* called while the work is owned - ie. while the PENDING bit is set.
|
|
*
|
|
* get_work_[g]cwq() can be used to obtain the gcwq or cwq
|
|
* corresponding to a work. gcwq is available once the work has been
|
|
* queued anywhere after initialization. cwq is available only from
|
|
* queueing until execution starts.
|
|
*/
|
|
static inline void set_work_data(struct work_struct *work, unsigned long data,
|
|
unsigned long flags)
|
|
{
|
|
BUG_ON(!work_pending(work));
|
|
atomic_long_set(&work->data, data | flags | work_static(work));
|
|
}
|
|
|
|
static void set_work_cwq(struct work_struct *work,
|
|
struct cpu_workqueue_struct *cwq,
|
|
unsigned long extra_flags)
|
|
{
|
|
set_work_data(work, (unsigned long)cwq,
|
|
WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags);
|
|
}
|
|
|
|
static void set_work_cpu(struct work_struct *work, unsigned int cpu)
|
|
{
|
|
set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING);
|
|
}
|
|
|
|
static void clear_work_data(struct work_struct *work)
|
|
{
|
|
set_work_data(work, WORK_STRUCT_NO_CPU, 0);
|
|
}
|
|
|
|
static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work)
|
|
{
|
|
unsigned long data = atomic_long_read(&work->data);
|
|
|
|
if (data & WORK_STRUCT_CWQ)
|
|
return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
|
|
else
|
|
return NULL;
|
|
}
|
|
|
|
static struct global_cwq *get_work_gcwq(struct work_struct *work)
|
|
{
|
|
unsigned long data = atomic_long_read(&work->data);
|
|
unsigned int cpu;
|
|
|
|
if (data & WORK_STRUCT_CWQ)
|
|
return ((struct cpu_workqueue_struct *)
|
|
(data & WORK_STRUCT_WQ_DATA_MASK))->pool->gcwq;
|
|
|
|
cpu = data >> WORK_STRUCT_FLAG_BITS;
|
|
if (cpu == WORK_CPU_NONE)
|
|
return NULL;
|
|
|
|
BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND);
|
|
return get_gcwq(cpu);
|
|
}
|
|
|
|
/*
|
|
* 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 gcwq->lock held.
|
|
*/
|
|
|
|
static bool __need_more_worker(struct worker_pool *pool)
|
|
{
|
|
return !atomic_read(get_pool_nr_running(pool));
|
|
}
|
|
|
|
/*
|
|
* 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 gcwq 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)
|
|
{
|
|
atomic_t *nr_running = get_pool_nr_running(pool);
|
|
|
|
return !list_empty(&pool->worklist) && atomic_read(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 I need to be the manager? */
|
|
static bool need_to_manage_workers(struct worker_pool *pool)
|
|
{
|
|
return need_to_create_worker(pool) ||
|
|
(pool->flags & POOL_MANAGE_WORKERS);
|
|
}
|
|
|
|
/* 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_mutex);
|
|
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 worker. Safe with preemption disabled */
|
|
static struct worker *first_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(gcwq->lock).
|
|
*/
|
|
static void wake_up_worker(struct worker_pool *pool)
|
|
{
|
|
struct worker *worker = first_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, unsigned int cpu)
|
|
{
|
|
struct worker *worker = kthread_data(task);
|
|
|
|
if (!(worker->flags & WORKER_NOT_RUNNING))
|
|
atomic_inc(get_pool_nr_running(worker->pool));
|
|
}
|
|
|
|
/**
|
|
* 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)
|
|
*
|
|
* RETURNS:
|
|
* Worker task on @cpu to wake up, %NULL if none.
|
|
*/
|
|
struct task_struct *wq_worker_sleeping(struct task_struct *task,
|
|
unsigned int cpu)
|
|
{
|
|
struct worker *worker = kthread_data(task), *to_wakeup = NULL;
|
|
struct worker_pool *pool = worker->pool;
|
|
atomic_t *nr_running = get_pool_nr_running(pool);
|
|
|
|
if (worker->flags & WORKER_NOT_RUNNING)
|
|
return NULL;
|
|
|
|
/* this can only happen on the local cpu */
|
|
BUG_ON(cpu != raw_smp_processor_id());
|
|
|
|
/*
|
|
* 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 gcwq
|
|
* lock is safe.
|
|
*/
|
|
if (atomic_dec_and_test(nr_running) && !list_empty(&pool->worklist))
|
|
to_wakeup = first_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
|
|
* @wakeup: wakeup an idle worker if necessary
|
|
*
|
|
* Set @flags in @worker->flags and adjust nr_running accordingly. If
|
|
* nr_running becomes zero and @wakeup is %true, an idle worker is
|
|
* woken up.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(gcwq->lock)
|
|
*/
|
|
static inline void worker_set_flags(struct worker *worker, unsigned int flags,
|
|
bool wakeup)
|
|
{
|
|
struct worker_pool *pool = worker->pool;
|
|
|
|
WARN_ON_ONCE(worker->task != current);
|
|
|
|
/*
|
|
* If transitioning into NOT_RUNNING, adjust nr_running and
|
|
* wake up an idle worker as necessary if requested by
|
|
* @wakeup.
|
|
*/
|
|
if ((flags & WORKER_NOT_RUNNING) &&
|
|
!(worker->flags & WORKER_NOT_RUNNING)) {
|
|
atomic_t *nr_running = get_pool_nr_running(pool);
|
|
|
|
if (wakeup) {
|
|
if (atomic_dec_and_test(nr_running) &&
|
|
!list_empty(&pool->worklist))
|
|
wake_up_worker(pool);
|
|
} else
|
|
atomic_dec(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(gcwq->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(get_pool_nr_running(pool));
|
|
}
|
|
|
|
/**
|
|
* busy_worker_head - return the busy hash head for a work
|
|
* @gcwq: gcwq of interest
|
|
* @work: work to be hashed
|
|
*
|
|
* Return hash head of @gcwq for @work.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(gcwq->lock).
|
|
*
|
|
* RETURNS:
|
|
* Pointer to the hash head.
|
|
*/
|
|
static struct hlist_head *busy_worker_head(struct global_cwq *gcwq,
|
|
struct work_struct *work)
|
|
{
|
|
const int base_shift = ilog2(sizeof(struct work_struct));
|
|
unsigned long v = (unsigned long)work;
|
|
|
|
/* simple shift and fold hash, do we need something better? */
|
|
v >>= base_shift;
|
|
v += v >> BUSY_WORKER_HASH_ORDER;
|
|
v &= BUSY_WORKER_HASH_MASK;
|
|
|
|
return &gcwq->busy_hash[v];
|
|
}
|
|
|
|
/**
|
|
* __find_worker_executing_work - find worker which is executing a work
|
|
* @gcwq: gcwq of interest
|
|
* @bwh: hash head as returned by busy_worker_head()
|
|
* @work: work to find worker for
|
|
*
|
|
* Find a worker which is executing @work on @gcwq. @bwh should be
|
|
* the hash head obtained by calling busy_worker_head() with the same
|
|
* work.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(gcwq->lock).
|
|
*
|
|
* RETURNS:
|
|
* Pointer to worker which is executing @work if found, NULL
|
|
* otherwise.
|
|
*/
|
|
static struct worker *__find_worker_executing_work(struct global_cwq *gcwq,
|
|
struct hlist_head *bwh,
|
|
struct work_struct *work)
|
|
{
|
|
struct worker *worker;
|
|
struct hlist_node *tmp;
|
|
|
|
hlist_for_each_entry(worker, tmp, bwh, hentry)
|
|
if (worker->current_work == work)
|
|
return worker;
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* find_worker_executing_work - find worker which is executing a work
|
|
* @gcwq: gcwq of interest
|
|
* @work: work to find worker for
|
|
*
|
|
* Find a worker which is executing @work on @gcwq. This function is
|
|
* identical to __find_worker_executing_work() except that this
|
|
* function calculates @bwh itself.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(gcwq->lock).
|
|
*
|
|
* RETURNS:
|
|
* Pointer to worker which is executing @work if found, NULL
|
|
* otherwise.
|
|
*/
|
|
static struct worker *find_worker_executing_work(struct global_cwq *gcwq,
|
|
struct work_struct *work)
|
|
{
|
|
return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work),
|
|
work);
|
|
}
|
|
|
|
/**
|
|
* insert_work - insert a work into gcwq
|
|
* @cwq: cwq @work belongs to
|
|
* @work: work to insert
|
|
* @head: insertion point
|
|
* @extra_flags: extra WORK_STRUCT_* flags to set
|
|
*
|
|
* Insert @work which belongs to @cwq into @gcwq after @head.
|
|
* @extra_flags is or'd to work_struct flags.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(gcwq->lock).
|
|
*/
|
|
static void insert_work(struct cpu_workqueue_struct *cwq,
|
|
struct work_struct *work, struct list_head *head,
|
|
unsigned int extra_flags)
|
|
{
|
|
struct worker_pool *pool = cwq->pool;
|
|
|
|
/* we own @work, set data and link */
|
|
set_work_cwq(work, cwq, extra_flags);
|
|
|
|
/*
|
|
* Ensure that we get the right work->data if we see the
|
|
* result of list_add() below, see try_to_grab_pending().
|
|
*/
|
|
smp_wmb();
|
|
|
|
list_add_tail(&work->entry, head);
|
|
|
|
/*
|
|
* Ensure either worker_sched_deactivated() 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. This is rather expensive and should only be used from
|
|
* cold paths.
|
|
*/
|
|
static bool is_chained_work(struct workqueue_struct *wq)
|
|
{
|
|
unsigned long flags;
|
|
unsigned int cpu;
|
|
|
|
for_each_gcwq_cpu(cpu) {
|
|
struct global_cwq *gcwq = get_gcwq(cpu);
|
|
struct worker *worker;
|
|
struct hlist_node *pos;
|
|
int i;
|
|
|
|
spin_lock_irqsave(&gcwq->lock, flags);
|
|
for_each_busy_worker(worker, i, pos, gcwq) {
|
|
if (worker->task != current)
|
|
continue;
|
|
spin_unlock_irqrestore(&gcwq->lock, flags);
|
|
/*
|
|
* I'm @worker, no locking necessary. See if @work
|
|
* is headed to the same workqueue.
|
|
*/
|
|
return worker->current_cwq->wq == wq;
|
|
}
|
|
spin_unlock_irqrestore(&gcwq->lock, flags);
|
|
}
|
|
return false;
|
|
}
|
|
|
|
static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
|
|
struct work_struct *work)
|
|
{
|
|
struct global_cwq *gcwq;
|
|
struct cpu_workqueue_struct *cwq;
|
|
struct list_head *worklist;
|
|
unsigned int work_flags;
|
|
unsigned long flags;
|
|
|
|
debug_work_activate(work);
|
|
|
|
/* if dying, only works from the same workqueue are allowed */
|
|
if (unlikely(wq->flags & WQ_DRAINING) &&
|
|
WARN_ON_ONCE(!is_chained_work(wq)))
|
|
return;
|
|
|
|
/* determine gcwq to use */
|
|
if (!(wq->flags & WQ_UNBOUND)) {
|
|
struct global_cwq *last_gcwq;
|
|
|
|
if (unlikely(cpu == WORK_CPU_UNBOUND))
|
|
cpu = raw_smp_processor_id();
|
|
|
|
/*
|
|
* It's multi cpu. If @wq is non-reentrant and @work
|
|
* was previously on a different cpu, it might still
|
|
* be running there, in which case the work needs to
|
|
* be queued on that cpu to guarantee non-reentrance.
|
|
*/
|
|
gcwq = get_gcwq(cpu);
|
|
if (wq->flags & WQ_NON_REENTRANT &&
|
|
(last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) {
|
|
struct worker *worker;
|
|
|
|
spin_lock_irqsave(&last_gcwq->lock, flags);
|
|
|
|
worker = find_worker_executing_work(last_gcwq, work);
|
|
|
|
if (worker && worker->current_cwq->wq == wq)
|
|
gcwq = last_gcwq;
|
|
else {
|
|
/* meh... not running there, queue here */
|
|
spin_unlock_irqrestore(&last_gcwq->lock, flags);
|
|
spin_lock_irqsave(&gcwq->lock, flags);
|
|
}
|
|
} else
|
|
spin_lock_irqsave(&gcwq->lock, flags);
|
|
} else {
|
|
gcwq = get_gcwq(WORK_CPU_UNBOUND);
|
|
spin_lock_irqsave(&gcwq->lock, flags);
|
|
}
|
|
|
|
/* gcwq determined, get cwq and queue */
|
|
cwq = get_cwq(gcwq->cpu, wq);
|
|
trace_workqueue_queue_work(cpu, cwq, work);
|
|
|
|
if (WARN_ON(!list_empty(&work->entry))) {
|
|
spin_unlock_irqrestore(&gcwq->lock, flags);
|
|
return;
|
|
}
|
|
|
|
cwq->nr_in_flight[cwq->work_color]++;
|
|
work_flags = work_color_to_flags(cwq->work_color);
|
|
|
|
if (likely(cwq->nr_active < cwq->max_active)) {
|
|
trace_workqueue_activate_work(work);
|
|
cwq->nr_active++;
|
|
worklist = &cwq->pool->worklist;
|
|
} else {
|
|
work_flags |= WORK_STRUCT_DELAYED;
|
|
worklist = &cwq->delayed_works;
|
|
}
|
|
|
|
insert_work(cwq, work, worklist, work_flags);
|
|
|
|
spin_unlock_irqrestore(&gcwq->lock, flags);
|
|
}
|
|
|
|
/**
|
|
* queue_work - queue work on a workqueue
|
|
* @wq: workqueue to use
|
|
* @work: work to queue
|
|
*
|
|
* Returns 0 if @work was already on a queue, non-zero otherwise.
|
|
*
|
|
* We queue the work to the CPU on which it was submitted, but if the CPU dies
|
|
* it can be processed by another CPU.
|
|
*/
|
|
int queue_work(struct workqueue_struct *wq, struct work_struct *work)
|
|
{
|
|
int ret;
|
|
|
|
ret = queue_work_on(get_cpu(), wq, work);
|
|
put_cpu();
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(queue_work);
|
|
|
|
/**
|
|
* queue_work_on - queue work on specific cpu
|
|
* @cpu: CPU number to execute work on
|
|
* @wq: workqueue to use
|
|
* @work: work to queue
|
|
*
|
|
* Returns 0 if @work was already on a queue, non-zero otherwise.
|
|
*
|
|
* We queue the work to a specific CPU, the caller must ensure it
|
|
* can't go away.
|
|
*/
|
|
int
|
|
queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
|
|
__queue_work(cpu, wq, work);
|
|
ret = 1;
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(queue_work_on);
|
|
|
|
static void delayed_work_timer_fn(unsigned long __data)
|
|
{
|
|
struct delayed_work *dwork = (struct delayed_work *)__data;
|
|
struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work);
|
|
|
|
__queue_work(smp_processor_id(), cwq->wq, &dwork->work);
|
|
}
|
|
|
|
/**
|
|
* queue_delayed_work - queue work on a workqueue after delay
|
|
* @wq: workqueue to use
|
|
* @dwork: delayable work to queue
|
|
* @delay: number of jiffies to wait before queueing
|
|
*
|
|
* Returns 0 if @work was already on a queue, non-zero otherwise.
|
|
*/
|
|
int queue_delayed_work(struct workqueue_struct *wq,
|
|
struct delayed_work *dwork, unsigned long delay)
|
|
{
|
|
if (delay == 0)
|
|
return queue_work(wq, &dwork->work);
|
|
|
|
return queue_delayed_work_on(-1, wq, dwork, delay);
|
|
}
|
|
EXPORT_SYMBOL_GPL(queue_delayed_work);
|
|
|
|
/**
|
|
* 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
|
|
*
|
|
* Returns 0 if @work was already on a queue, non-zero otherwise.
|
|
*/
|
|
int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
|
|
struct delayed_work *dwork, unsigned long delay)
|
|
{
|
|
int ret = 0;
|
|
struct timer_list *timer = &dwork->timer;
|
|
struct work_struct *work = &dwork->work;
|
|
|
|
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
|
|
unsigned int lcpu;
|
|
|
|
BUG_ON(timer_pending(timer));
|
|
BUG_ON(!list_empty(&work->entry));
|
|
|
|
timer_stats_timer_set_start_info(&dwork->timer);
|
|
|
|
/*
|
|
* This stores cwq for the moment, for the timer_fn.
|
|
* Note that the work's gcwq is preserved to allow
|
|
* reentrance detection for delayed works.
|
|
*/
|
|
if (!(wq->flags & WQ_UNBOUND)) {
|
|
struct global_cwq *gcwq = get_work_gcwq(work);
|
|
|
|
if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND)
|
|
lcpu = gcwq->cpu;
|
|
else
|
|
lcpu = raw_smp_processor_id();
|
|
} else
|
|
lcpu = WORK_CPU_UNBOUND;
|
|
|
|
set_work_cwq(work, get_cwq(lcpu, wq), 0);
|
|
|
|
timer->expires = jiffies + delay;
|
|
timer->data = (unsigned long)dwork;
|
|
timer->function = delayed_work_timer_fn;
|
|
|
|
if (unlikely(cpu >= 0))
|
|
add_timer_on(timer, cpu);
|
|
else
|
|
add_timer(timer);
|
|
ret = 1;
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(queue_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(gcwq->lock).
|
|
*/
|
|
static void worker_enter_idle(struct worker *worker)
|
|
{
|
|
struct worker_pool *pool = worker->pool;
|
|
struct global_cwq *gcwq = pool->gcwq;
|
|
|
|
BUG_ON(worker->flags & WORKER_IDLE);
|
|
BUG_ON(!list_empty(&worker->entry) &&
|
|
(worker->hentry.next || worker->hentry.pprev));
|
|
|
|
/* can't use worker_set_flags(), also called from start_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 gcwq_unbind_fn() releases
|
|
* gcwq->lock between setting %WORKER_UNBOUND and zapping
|
|
* nr_running, the warning may trigger spuriously. Check iff
|
|
* unbind is not in progress.
|
|
*/
|
|
WARN_ON_ONCE(!(gcwq->flags & GCWQ_DISASSOCIATED) &&
|
|
pool->nr_workers == pool->nr_idle &&
|
|
atomic_read(get_pool_nr_running(pool)));
|
|
}
|
|
|
|
/**
|
|
* worker_leave_idle - leave idle state
|
|
* @worker: worker which is leaving idle state
|
|
*
|
|
* @worker is leaving idle state. Update stats.
|
|
*
|
|
* LOCKING:
|
|
* spin_lock_irq(gcwq->lock).
|
|
*/
|
|
static void worker_leave_idle(struct worker *worker)
|
|
{
|
|
struct worker_pool *pool = worker->pool;
|
|
|
|
BUG_ON(!(worker->flags & WORKER_IDLE));
|
|
worker_clr_flags(worker, WORKER_IDLE);
|
|
pool->nr_idle--;
|
|
list_del_init(&worker->entry);
|
|
}
|
|
|
|
/**
|
|
* worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq
|
|
* @worker: self
|
|
*
|
|
* Works which are scheduled while the cpu is online must at least be
|
|
* scheduled to a worker which is bound to the cpu so that if they are
|
|
* flushed from cpu callbacks while cpu is going down, they are
|
|
* guaranteed to execute on the cpu.
|
|
*
|
|
* This function is to be used by rogue workers and rescuers to bind
|
|
* themselves to the target cpu and may race with cpu going down or
|
|
* coming online. kthread_bind() can't be used because it may put the
|
|
* worker to already dead cpu and set_cpus_allowed_ptr() can't be used
|
|
* verbatim as it's best effort and blocking and gcwq may be
|
|
* [dis]associated in the meantime.
|
|
*
|
|
* This function tries set_cpus_allowed() and locks gcwq and verifies the
|
|
* binding against %GCWQ_DISASSOCIATED which is set during
|
|
* %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker
|
|
* enters idle state or fetches works without dropping lock, it can
|
|
* guarantee the scheduling requirement described in the first paragraph.
|
|
*
|
|
* CONTEXT:
|
|
* Might sleep. Called without any lock but returns with gcwq->lock
|
|
* held.
|
|
*
|
|
* RETURNS:
|
|
* %true if the associated gcwq is online (@worker is successfully
|
|
* bound), %false if offline.
|
|
*/
|
|
static bool worker_maybe_bind_and_lock(struct worker *worker)
|
|
__acquires(&gcwq->lock)
|
|
{
|
|
struct global_cwq *gcwq = worker->pool->gcwq;
|
|
struct task_struct *task = worker->task;
|
|
|
|
while (true) {
|
|
/*
|
|
* The following call may fail, succeed or succeed
|
|
* without actually migrating the task to the cpu if
|
|
* it races with cpu hotunplug operation. Verify
|
|
* against GCWQ_DISASSOCIATED.
|
|
*/
|
|
if (!(gcwq->flags & GCWQ_DISASSOCIATED))
|
|
set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu));
|
|
|
|
spin_lock_irq(&gcwq->lock);
|
|
if (gcwq->flags & GCWQ_DISASSOCIATED)
|
|
return false;
|
|
if (task_cpu(task) == gcwq->cpu &&
|
|
cpumask_equal(¤t->cpus_allowed,
|
|
get_cpu_mask(gcwq->cpu)))
|
|
return true;
|
|
spin_unlock_irq(&gcwq->lock);
|
|
|
|
/*
|
|
* We've raced with CPU hot[un]plug. Give it a breather
|
|
* and retry migration. cond_resched() is required here;
|
|
* otherwise, we might deadlock against cpu_stop trying to
|
|
* bring down the CPU on non-preemptive kernel.
|
|
*/
|
|
cpu_relax();
|
|
cond_resched();
|
|
}
|
|
}
|
|
|
|
struct idle_rebind {
|
|
int cnt; /* # workers to be rebound */
|
|
struct completion done; /* all workers rebound */
|
|
};
|
|
|
|
/*
|
|
* Rebind an idle @worker to its CPU. During CPU onlining, this has to
|
|
* happen synchronously for idle workers. worker_thread() will test
|
|
* %WORKER_REBIND before leaving idle and call this function.
|
|
*/
|
|
static void idle_worker_rebind(struct worker *worker)
|
|
{
|
|
struct global_cwq *gcwq = worker->pool->gcwq;
|
|
|
|
/* CPU must be online at this point */
|
|
WARN_ON(!worker_maybe_bind_and_lock(worker));
|
|
if (!--worker->idle_rebind->cnt)
|
|
complete(&worker->idle_rebind->done);
|
|
spin_unlock_irq(&worker->pool->gcwq->lock);
|
|
|
|
/* we did our part, wait for rebind_workers() to finish up */
|
|
wait_event(gcwq->rebind_hold, !(worker->flags & WORKER_REBIND));
|
|
}
|
|
|
|
/*
|
|
* Function for @worker->rebind.work used to rebind unbound busy workers to
|
|
* the associated cpu which is coming back online. This is scheduled by
|
|
* cpu up but can race with other cpu hotplug operations and may be
|
|
* executed twice without intervening cpu down.
|
|
*/
|
|
static void busy_worker_rebind_fn(struct work_struct *work)
|
|
{
|
|
struct worker *worker = container_of(work, struct worker, rebind_work);
|
|
struct global_cwq *gcwq = worker->pool->gcwq;
|
|
|
|
if (worker_maybe_bind_and_lock(worker))
|
|
worker_clr_flags(worker, WORKER_REBIND);
|
|
|
|
spin_unlock_irq(&gcwq->lock);
|
|
}
|
|
|
|
/**
|
|
* rebind_workers - rebind all workers of a gcwq to the associated CPU
|
|
* @gcwq: gcwq of interest
|
|
*
|
|
* @gcwq->cpu is coming online. Rebind all workers to the CPU. Rebinding
|
|
* is different for idle and busy ones.
|
|
*
|
|
* The idle ones should be rebound synchronously and idle rebinding should
|
|
* be complete before any worker starts executing work items with
|
|
* concurrency management enabled; otherwise, scheduler may oops trying to
|
|
* wake up non-local idle worker from wq_worker_sleeping().
|
|
*
|
|
* This is achieved by repeatedly requesting rebinding until all idle
|
|
* workers are known to have been rebound under @gcwq->lock and holding all
|
|
* idle workers from becoming busy until idle rebinding is complete.
|
|
*
|
|
* Once idle workers are rebound, busy workers can be rebound as they
|
|
* finish executing their current work items. Queueing the rebind work at
|
|
* the head of their scheduled lists is enough. Note that nr_running will
|
|
* be properbly bumped as busy workers rebind.
|
|
*
|
|
* On return, all workers are guaranteed to either be bound or have rebind
|
|
* work item scheduled.
|
|
*/
|
|
static void rebind_workers(struct global_cwq *gcwq)
|
|
__releases(&gcwq->lock) __acquires(&gcwq->lock)
|
|
{
|
|
struct idle_rebind idle_rebind;
|
|
struct worker_pool *pool;
|
|
struct worker *worker;
|
|
struct hlist_node *pos;
|
|
int i;
|
|
|
|
lockdep_assert_held(&gcwq->lock);
|
|
|
|
for_each_worker_pool(pool, gcwq)
|
|
lockdep_assert_held(&pool->manager_mutex);
|
|
|
|
/*
|
|
* Rebind idle workers. Interlocked both ways. We wait for
|
|
* workers to rebind via @idle_rebind.done. Workers will wait for
|
|
* us to finish up by watching %WORKER_REBIND.
|
|
*/
|
|
init_completion(&idle_rebind.done);
|
|
retry:
|
|
idle_rebind.cnt = 1;
|
|
INIT_COMPLETION(idle_rebind.done);
|
|
|
|
/* set REBIND and kick idle ones, we'll wait for these later */
|
|
for_each_worker_pool(pool, gcwq) {
|
|
list_for_each_entry(worker, &pool->idle_list, entry) {
|
|
if (worker->flags & WORKER_REBIND)
|
|
continue;
|
|
|
|
/* morph UNBOUND to REBIND */
|
|
worker->flags &= ~WORKER_UNBOUND;
|
|
worker->flags |= WORKER_REBIND;
|
|
|
|
idle_rebind.cnt++;
|
|
worker->idle_rebind = &idle_rebind;
|
|
|
|
/* worker_thread() will call idle_worker_rebind() */
|
|
wake_up_process(worker->task);
|
|
}
|
|
}
|
|
|
|
if (--idle_rebind.cnt) {
|
|
spin_unlock_irq(&gcwq->lock);
|
|
wait_for_completion(&idle_rebind.done);
|
|
spin_lock_irq(&gcwq->lock);
|
|
/* busy ones might have become idle while waiting, retry */
|
|
goto retry;
|
|
}
|
|
|
|
/*
|
|
* All idle workers are rebound and waiting for %WORKER_REBIND to
|
|
* be cleared inside idle_worker_rebind(). Clear and release.
|
|
* Clearing %WORKER_REBIND from this foreign context is safe
|
|
* because these workers are still guaranteed to be idle.
|
|
*/
|
|
for_each_worker_pool(pool, gcwq)
|
|
list_for_each_entry(worker, &pool->idle_list, entry)
|
|
worker->flags &= ~WORKER_REBIND;
|
|
|
|
wake_up_all(&gcwq->rebind_hold);
|
|
|
|
/* rebind busy workers */
|
|
for_each_busy_worker(worker, i, pos, gcwq) {
|
|
struct work_struct *rebind_work = &worker->rebind_work;
|
|
|
|
/* morph UNBOUND to REBIND */
|
|
worker->flags &= ~WORKER_UNBOUND;
|
|
worker->flags |= WORKER_REBIND;
|
|
|
|
if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
|
|
work_data_bits(rebind_work)))
|
|
continue;
|
|
|
|
/* wq doesn't matter, use the default one */
|
|
debug_work_activate(rebind_work);
|
|
insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work,
|
|
worker->scheduled.next,
|
|
work_color_to_flags(WORK_NO_COLOR));
|
|
}
|
|
}
|
|
|
|
static struct worker *alloc_worker(void)
|
|
{
|
|
struct worker *worker;
|
|
|
|
worker = kzalloc(sizeof(*worker), GFP_KERNEL);
|
|
if (worker) {
|
|
INIT_LIST_HEAD(&worker->entry);
|
|
INIT_LIST_HEAD(&worker->scheduled);
|
|
INIT_WORK(&worker->rebind_work, busy_worker_rebind_fn);
|
|
/* on creation a worker is in !idle && prep state */
|
|
worker->flags = WORKER_PREP;
|
|
}
|
|
return worker;
|
|
}
|
|
|
|
/**
|
|
* create_worker - create a new workqueue worker
|
|
* @pool: pool the new worker will belong to
|
|
*
|
|
* Create a new worker which is bound to @pool. The returned worker
|
|
* can be started by calling start_worker() or destroyed using
|
|
* destroy_worker().
|
|
*
|
|
* CONTEXT:
|
|
* Might sleep. Does GFP_KERNEL allocations.
|
|
*
|
|
* RETURNS:
|
|
* Pointer to the newly created worker.
|
|
*/
|
|
static struct worker *create_worker(struct worker_pool *pool)
|
|
{
|
|
struct global_cwq *gcwq = pool->gcwq;
|
|
const char *pri = worker_pool_pri(pool) ? "H" : "";
|
|
struct worker *worker = NULL;
|
|
int id = -1;
|
|
|
|
spin_lock_irq(&gcwq->lock);
|
|
while (ida_get_new(&pool->worker_ida, &id)) {
|
|
spin_unlock_irq(&gcwq->lock);
|
|
if (!ida_pre_get(&pool->worker_ida, GFP_KERNEL))
|
|
goto fail;
|
|
spin_lock_irq(&gcwq->lock);
|
|
}
|
|
spin_unlock_irq(&gcwq->lock);
|
|
|
|
worker = alloc_worker();
|
|
if (!worker)
|
|
goto fail;
|
|
|
|
worker->pool = pool;
|
|
worker->id = id;
|
|
|
|
if (gcwq->cpu != WORK_CPU_UNBOUND)
|
|
worker->task = kthread_create_on_node(worker_thread,
|
|
worker, cpu_to_node(gcwq->cpu),
|
|
"kworker/%u:%d%s", gcwq->cpu, id, pri);
|
|
else
|
|
worker->task = kthread_create(worker_thread, worker,
|
|
"kworker/u:%d%s", id, pri);
|
|
if (IS_ERR(worker->task))
|
|
goto fail;
|
|
|
|
if (worker_pool_pri(pool))
|
|
set_user_nice(worker->task, HIGHPRI_NICE_LEVEL);
|
|
|
|
/*
|
|
* Determine CPU binding of the new worker depending on
|
|
* %GCWQ_DISASSOCIATED. The caller is responsible for ensuring the
|
|
* flag remains stable across this function. See the comments
|
|
* above the flag definition for details.
|
|
*
|
|
* As an unbound worker may later become a regular one if CPU comes
|
|
* online, make sure every worker has %PF_THREAD_BOUND set.
|
|
*/
|
|
if (!(gcwq->flags & GCWQ_DISASSOCIATED)) {
|
|
kthread_bind(worker->task, gcwq->cpu);
|
|
} else {
|
|
worker->task->flags |= PF_THREAD_BOUND;
|
|
worker->flags |= WORKER_UNBOUND;
|
|
}
|
|
|
|
return worker;
|
|
fail:
|
|
if (id >= 0) {
|
|
spin_lock_irq(&gcwq->lock);
|
|
ida_remove(&pool->worker_ida, id);
|
|
spin_unlock_irq(&gcwq->lock);
|
|
}
|
|
kfree(worker);
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* start_worker - start a newly created worker
|
|
* @worker: worker to start
|
|
*
|
|
* Make the gcwq aware of @worker and start it.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(gcwq->lock).
|
|
*/
|
|
static void start_worker(struct worker *worker)
|
|
{
|
|
worker->flags |= WORKER_STARTED;
|
|
worker->pool->nr_workers++;
|
|
worker_enter_idle(worker);
|
|
wake_up_process(worker->task);
|
|
}
|
|
|
|
/**
|
|
* destroy_worker - destroy a workqueue worker
|
|
* @worker: worker to be destroyed
|
|
*
|
|
* Destroy @worker and adjust @gcwq stats accordingly.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(gcwq->lock) which is released and regrabbed.
|
|
*/
|
|
static void destroy_worker(struct worker *worker)
|
|
{
|
|
struct worker_pool *pool = worker->pool;
|
|
struct global_cwq *gcwq = pool->gcwq;
|
|
int id = worker->id;
|
|
|
|
/* sanity check frenzy */
|
|
BUG_ON(worker->current_work);
|
|
BUG_ON(!list_empty(&worker->scheduled));
|
|
|
|
if (worker->flags & WORKER_STARTED)
|
|
pool->nr_workers--;
|
|
if (worker->flags & WORKER_IDLE)
|
|
pool->nr_idle--;
|
|
|
|
list_del_init(&worker->entry);
|
|
worker->flags |= WORKER_DIE;
|
|
|
|
spin_unlock_irq(&gcwq->lock);
|
|
|
|
kthread_stop(worker->task);
|
|
kfree(worker);
|
|
|
|
spin_lock_irq(&gcwq->lock);
|
|
ida_remove(&pool->worker_ida, id);
|
|
}
|
|
|
|
static void idle_worker_timeout(unsigned long __pool)
|
|
{
|
|
struct worker_pool *pool = (void *)__pool;
|
|
struct global_cwq *gcwq = pool->gcwq;
|
|
|
|
spin_lock_irq(&gcwq->lock);
|
|
|
|
if (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);
|
|
else {
|
|
/* it's been idle for too long, wake up manager */
|
|
pool->flags |= POOL_MANAGE_WORKERS;
|
|
wake_up_worker(pool);
|
|
}
|
|
}
|
|
|
|
spin_unlock_irq(&gcwq->lock);
|
|
}
|
|
|
|
static bool send_mayday(struct work_struct *work)
|
|
{
|
|
struct cpu_workqueue_struct *cwq = get_work_cwq(work);
|
|
struct workqueue_struct *wq = cwq->wq;
|
|
unsigned int cpu;
|
|
|
|
if (!(wq->flags & WQ_RESCUER))
|
|
return false;
|
|
|
|
/* mayday mayday mayday */
|
|
cpu = cwq->pool->gcwq->cpu;
|
|
/* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */
|
|
if (cpu == WORK_CPU_UNBOUND)
|
|
cpu = 0;
|
|
if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask))
|
|
wake_up_process(wq->rescuer->task);
|
|
return true;
|
|
}
|
|
|
|
static void gcwq_mayday_timeout(unsigned long __pool)
|
|
{
|
|
struct worker_pool *pool = (void *)__pool;
|
|
struct global_cwq *gcwq = pool->gcwq;
|
|
struct work_struct *work;
|
|
|
|
spin_lock_irq(&gcwq->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_irq(&gcwq->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(gcwq->lock) which may be released and regrabbed
|
|
* multiple times. Does GFP_KERNEL allocations. Called only from
|
|
* manager.
|
|
*
|
|
* RETURNS:
|
|
* false if no action was taken and gcwq->lock stayed locked, true
|
|
* otherwise.
|
|
*/
|
|
static bool maybe_create_worker(struct worker_pool *pool)
|
|
__releases(&gcwq->lock)
|
|
__acquires(&gcwq->lock)
|
|
{
|
|
struct global_cwq *gcwq = pool->gcwq;
|
|
|
|
if (!need_to_create_worker(pool))
|
|
return false;
|
|
restart:
|
|
spin_unlock_irq(&gcwq->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) {
|
|
struct worker *worker;
|
|
|
|
worker = create_worker(pool);
|
|
if (worker) {
|
|
del_timer_sync(&pool->mayday_timer);
|
|
spin_lock_irq(&gcwq->lock);
|
|
start_worker(worker);
|
|
BUG_ON(need_to_create_worker(pool));
|
|
return true;
|
|
}
|
|
|
|
if (!need_to_create_worker(pool))
|
|
break;
|
|
|
|
__set_current_state(TASK_INTERRUPTIBLE);
|
|
schedule_timeout(CREATE_COOLDOWN);
|
|
|
|
if (!need_to_create_worker(pool))
|
|
break;
|
|
}
|
|
|
|
del_timer_sync(&pool->mayday_timer);
|
|
spin_lock_irq(&gcwq->lock);
|
|
if (need_to_create_worker(pool))
|
|
goto restart;
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* maybe_destroy_worker - destroy workers which have been idle for a while
|
|
* @pool: pool to destroy workers for
|
|
*
|
|
* Destroy @pool workers which have been idle for longer than
|
|
* IDLE_WORKER_TIMEOUT.
|
|
*
|
|
* LOCKING:
|
|
* spin_lock_irq(gcwq->lock) which may be released and regrabbed
|
|
* multiple times. Called only from manager.
|
|
*
|
|
* RETURNS:
|
|
* false if no action was taken and gcwq->lock stayed locked, true
|
|
* otherwise.
|
|
*/
|
|
static bool maybe_destroy_workers(struct worker_pool *pool)
|
|
{
|
|
bool ret = false;
|
|
|
|
while (too_many_workers(pool)) {
|
|
struct worker *worker;
|
|
unsigned long expires;
|
|
|
|
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);
|
|
ret = true;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* manage_workers - manage worker pool
|
|
* @worker: self
|
|
*
|
|
* Assume the manager role and manage gcwq worker pool @worker belongs
|
|
* to. At any given time, there can be only zero or one manager per
|
|
* gcwq. 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(gcwq->lock) which may be released and regrabbed
|
|
* multiple times. Does GFP_KERNEL allocations.
|
|
*
|
|
* RETURNS:
|
|
* false if no action was taken and gcwq->lock stayed locked, true if
|
|
* some action was taken.
|
|
*/
|
|
static bool manage_workers(struct worker *worker)
|
|
{
|
|
struct worker_pool *pool = worker->pool;
|
|
bool ret = false;
|
|
|
|
if (!mutex_trylock(&pool->manager_mutex))
|
|
return ret;
|
|
|
|
pool->flags &= ~POOL_MANAGE_WORKERS;
|
|
|
|
/*
|
|
* Destroy and then create so that may_start_working() is true
|
|
* on return.
|
|
*/
|
|
ret |= maybe_destroy_workers(pool);
|
|
ret |= maybe_create_worker(pool);
|
|
|
|
mutex_unlock(&pool->manager_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* 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(gcwq->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;
|
|
}
|
|
|
|
static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
|
|
{
|
|
struct work_struct *work = list_first_entry(&cwq->delayed_works,
|
|
struct work_struct, entry);
|
|
|
|
trace_workqueue_activate_work(work);
|
|
move_linked_works(work, &cwq->pool->worklist, NULL);
|
|
__clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
|
|
cwq->nr_active++;
|
|
}
|
|
|
|
/**
|
|
* cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
|
|
* @cwq: cwq of interest
|
|
* @color: color of work which left the queue
|
|
* @delayed: for a delayed work
|
|
*
|
|
* A work either has completed or is removed from pending queue,
|
|
* decrement nr_in_flight of its cwq and handle workqueue flushing.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(gcwq->lock).
|
|
*/
|
|
static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color,
|
|
bool delayed)
|
|
{
|
|
/* ignore uncolored works */
|
|
if (color == WORK_NO_COLOR)
|
|
return;
|
|
|
|
cwq->nr_in_flight[color]--;
|
|
|
|
if (!delayed) {
|
|
cwq->nr_active--;
|
|
if (!list_empty(&cwq->delayed_works)) {
|
|
/* one down, submit a delayed one */
|
|
if (cwq->nr_active < cwq->max_active)
|
|
cwq_activate_first_delayed(cwq);
|
|
}
|
|
}
|
|
|
|
/* is flush in progress and are we at the flushing tip? */
|
|
if (likely(cwq->flush_color != color))
|
|
return;
|
|
|
|
/* are there still in-flight works? */
|
|
if (cwq->nr_in_flight[color])
|
|
return;
|
|
|
|
/* this cwq is done, clear flush_color */
|
|
cwq->flush_color = -1;
|
|
|
|
/*
|
|
* If this was the last cwq, wake up the first flusher. It
|
|
* will handle the rest.
|
|
*/
|
|
if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush))
|
|
complete(&cwq->wq->first_flusher->done);
|
|
}
|
|
|
|
/**
|
|
* 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(gcwq->lock) which is released and regrabbed.
|
|
*/
|
|
static void process_one_work(struct worker *worker, struct work_struct *work)
|
|
__releases(&gcwq->lock)
|
|
__acquires(&gcwq->lock)
|
|
{
|
|
struct cpu_workqueue_struct *cwq = get_work_cwq(work);
|
|
struct worker_pool *pool = worker->pool;
|
|
struct global_cwq *gcwq = pool->gcwq;
|
|
struct hlist_head *bwh = busy_worker_head(gcwq, work);
|
|
bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE;
|
|
work_func_t f = work->func;
|
|
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. DISASSOCIATED test is
|
|
* necessary to avoid spurious warnings from rescuers servicing the
|
|
* unbound or a disassociated gcwq.
|
|
*/
|
|
WARN_ON_ONCE(!(worker->flags & (WORKER_UNBOUND | WORKER_REBIND)) &&
|
|
!(gcwq->flags & GCWQ_DISASSOCIATED) &&
|
|
raw_smp_processor_id() != gcwq->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(gcwq, bwh, work);
|
|
if (unlikely(collision)) {
|
|
move_linked_works(work, &collision->scheduled, NULL);
|
|
return;
|
|
}
|
|
|
|
/* claim and process */
|
|
debug_work_deactivate(work);
|
|
hlist_add_head(&worker->hentry, bwh);
|
|
worker->current_work = work;
|
|
worker->current_cwq = cwq;
|
|
work_color = get_work_color(work);
|
|
|
|
/* record the current cpu number in the work data and dequeue */
|
|
set_work_cpu(work, gcwq->cpu);
|
|
list_del_init(&work->entry);
|
|
|
|
/*
|
|
* CPU intensive works don't participate in concurrency
|
|
* management. They're the scheduler's responsibility.
|
|
*/
|
|
if (unlikely(cpu_intensive))
|
|
worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);
|
|
|
|
/*
|
|
* Unbound gcwq isn't concurrency managed and work items should be
|
|
* executed ASAP. Wake up another worker if necessary.
|
|
*/
|
|
if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool))
|
|
wake_up_worker(pool);
|
|
|
|
spin_unlock_irq(&gcwq->lock);
|
|
|
|
work_clear_pending(work);
|
|
lock_map_acquire_read(&cwq->wq->lockdep_map);
|
|
lock_map_acquire(&lockdep_map);
|
|
trace_workqueue_execute_start(work);
|
|
f(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(&cwq->wq->lockdep_map);
|
|
|
|
if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
|
|
printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
|
|
"%s/0x%08x/%d\n",
|
|
current->comm, preempt_count(), task_pid_nr(current));
|
|
printk(KERN_ERR " last function: ");
|
|
print_symbol("%s\n", (unsigned long)f);
|
|
debug_show_held_locks(current);
|
|
dump_stack();
|
|
}
|
|
|
|
spin_lock_irq(&gcwq->lock);
|
|
|
|
/* clear cpu intensive status */
|
|
if (unlikely(cpu_intensive))
|
|
worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
|
|
|
|
/* we're done with it, release */
|
|
hlist_del_init(&worker->hentry);
|
|
worker->current_work = NULL;
|
|
worker->current_cwq = NULL;
|
|
cwq_dec_nr_in_flight(cwq, work_color, false);
|
|
}
|
|
|
|
/**
|
|
* 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(gcwq->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 gcwq worker thread function. There's a single dynamic pool of
|
|
* these per each cpu. These workers process all works regardless of
|
|
* their specific target workqueue. The only exception is works which
|
|
* belong to workqueues with a rescuer which will be explained in
|
|
* rescuer_thread().
|
|
*/
|
|
static int worker_thread(void *__worker)
|
|
{
|
|
struct worker *worker = __worker;
|
|
struct worker_pool *pool = worker->pool;
|
|
struct global_cwq *gcwq = pool->gcwq;
|
|
|
|
/* tell the scheduler that this is a workqueue worker */
|
|
worker->task->flags |= PF_WQ_WORKER;
|
|
woke_up:
|
|
spin_lock_irq(&gcwq->lock);
|
|
|
|
/*
|
|
* DIE can be set only while idle and REBIND set while busy has
|
|
* @worker->rebind_work scheduled. Checking here is enough.
|
|
*/
|
|
if (unlikely(worker->flags & (WORKER_REBIND | WORKER_DIE))) {
|
|
spin_unlock_irq(&gcwq->lock);
|
|
|
|
if (worker->flags & WORKER_DIE) {
|
|
worker->task->flags &= ~PF_WQ_WORKER;
|
|
return 0;
|
|
}
|
|
|
|
idle_worker_rebind(worker);
|
|
goto woke_up;
|
|
}
|
|
|
|
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.
|
|
*/
|
|
BUG_ON(!list_empty(&worker->scheduled));
|
|
|
|
/*
|
|
* When control reaches this point, we're guaranteed to have
|
|
* at least one idle worker or that someone else has already
|
|
* assumed the manager role.
|
|
*/
|
|
worker_clr_flags(worker, WORKER_PREP);
|
|
|
|
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, false);
|
|
sleep:
|
|
if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker))
|
|
goto recheck;
|
|
|
|
/*
|
|
* gcwq->lock is held and there's no work to process and no
|
|
* need to manage, sleep. Workers are woken up only while
|
|
* holding gcwq->lock or from local cpu, so setting the
|
|
* current state before releasing gcwq->lock is enough to
|
|
* prevent losing any event.
|
|
*/
|
|
worker_enter_idle(worker);
|
|
__set_current_state(TASK_INTERRUPTIBLE);
|
|
spin_unlock_irq(&gcwq->lock);
|
|
schedule();
|
|
goto woke_up;
|
|
}
|
|
|
|
/**
|
|
* rescuer_thread - the rescuer thread function
|
|
* @__wq: the associated workqueue
|
|
*
|
|
* Workqueue rescuer thread function. There's one rescuer for each
|
|
* workqueue which has WQ_RESCUER set.
|
|
*
|
|
* Regular work processing on a gcwq 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 gcwq summons rescuers of all
|
|
* workqueues which have works queued on the gcwq and let them process
|
|
* those works so that forward progress can be guaranteed.
|
|
*
|
|
* This should happen rarely.
|
|
*/
|
|
static int rescuer_thread(void *__wq)
|
|
{
|
|
struct workqueue_struct *wq = __wq;
|
|
struct worker *rescuer = wq->rescuer;
|
|
struct list_head *scheduled = &rescuer->scheduled;
|
|
bool is_unbound = wq->flags & WQ_UNBOUND;
|
|
unsigned int cpu;
|
|
|
|
set_user_nice(current, RESCUER_NICE_LEVEL);
|
|
repeat:
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
|
|
if (kthread_should_stop())
|
|
return 0;
|
|
|
|
/*
|
|
* See whether any cpu is asking for help. Unbounded
|
|
* workqueues use cpu 0 in mayday_mask for CPU_UNBOUND.
|
|
*/
|
|
for_each_mayday_cpu(cpu, wq->mayday_mask) {
|
|
unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu;
|
|
struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq);
|
|
struct worker_pool *pool = cwq->pool;
|
|
struct global_cwq *gcwq = pool->gcwq;
|
|
struct work_struct *work, *n;
|
|
|
|
__set_current_state(TASK_RUNNING);
|
|
mayday_clear_cpu(cpu, wq->mayday_mask);
|
|
|
|
/* migrate to the target cpu if possible */
|
|
rescuer->pool = pool;
|
|
worker_maybe_bind_and_lock(rescuer);
|
|
|
|
/*
|
|
* Slurp in all works issued via this workqueue and
|
|
* process'em.
|
|
*/
|
|
BUG_ON(!list_empty(&rescuer->scheduled));
|
|
list_for_each_entry_safe(work, n, &pool->worklist, entry)
|
|
if (get_work_cwq(work) == cwq)
|
|
move_linked_works(work, scheduled, &n);
|
|
|
|
process_scheduled_works(rescuer);
|
|
|
|
/*
|
|
* Leave this gcwq. If keep_working() is %true, notify a
|
|
* regular worker; otherwise, we end up with 0 concurrency
|
|
* and stalling the execution.
|
|
*/
|
|
if (keep_working(pool))
|
|
wake_up_worker(pool);
|
|
|
|
spin_unlock_irq(&gcwq->lock);
|
|
}
|
|
|
|
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
|
|
* @cwq: cwq 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 cwq from @target.
|
|
*
|
|
* CONTEXT:
|
|
* spin_lock_irq(gcwq->lock).
|
|
*/
|
|
static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
|
|
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 gcwq->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(cwq, &barr->work, head,
|
|
work_color_to_flags(WORK_NO_COLOR) | linked);
|
|
}
|
|
|
|
/**
|
|
* flush_workqueue_prep_cwqs - prepare cwqs 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 cwqs for workqueue flushing.
|
|
*
|
|
* If @flush_color is non-negative, flush_color on all cwqs should be
|
|
* -1. If no cwq has in-flight commands at the specified color, all
|
|
* cwq->flush_color's stay at -1 and %false is returned. If any cwq
|
|
* has in flight commands, its cwq->flush_color is set to
|
|
* @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq
|
|
* 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 cwqs should have the same
|
|
* work_color which is previous to @work_color and all will be
|
|
* advanced to @work_color.
|
|
*
|
|
* CONTEXT:
|
|
* mutex_lock(wq->flush_mutex).
|
|
*
|
|
* RETURNS:
|
|
* %true if @flush_color >= 0 and there's something to flush. %false
|
|
* otherwise.
|
|
*/
|
|
static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq,
|
|
int flush_color, int work_color)
|
|
{
|
|
bool wait = false;
|
|
unsigned int cpu;
|
|
|
|
if (flush_color >= 0) {
|
|
BUG_ON(atomic_read(&wq->nr_cwqs_to_flush));
|
|
atomic_set(&wq->nr_cwqs_to_flush, 1);
|
|
}
|
|
|
|
for_each_cwq_cpu(cpu, wq) {
|
|
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
|
|
struct global_cwq *gcwq = cwq->pool->gcwq;
|
|
|
|
spin_lock_irq(&gcwq->lock);
|
|
|
|
if (flush_color >= 0) {
|
|
BUG_ON(cwq->flush_color != -1);
|
|
|
|
if (cwq->nr_in_flight[flush_color]) {
|
|
cwq->flush_color = flush_color;
|
|
atomic_inc(&wq->nr_cwqs_to_flush);
|
|
wait = true;
|
|
}
|
|
}
|
|
|
|
if (work_color >= 0) {
|
|
BUG_ON(work_color != work_next_color(cwq->work_color));
|
|
cwq->work_color = work_color;
|
|
}
|
|
|
|
spin_unlock_irq(&gcwq->lock);
|
|
}
|
|
|
|
if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush))
|
|
complete(&wq->first_flusher->done);
|
|
|
|
return wait;
|
|
}
|
|
|
|
/**
|
|
* flush_workqueue - ensure that any scheduled work has run to completion.
|
|
* @wq: workqueue to flush
|
|
*
|
|
* Forces execution of the workqueue and blocks until its completion.
|
|
* This is typically used in driver shutdown handlers.
|
|
*
|
|
* We sleep until all works which were queued on entry have been handled,
|
|
* but we are 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->flush_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.
|
|
*/
|
|
BUG_ON(!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 */
|
|
BUG_ON(wq->flush_color != this_flusher.flush_color);
|
|
|
|
wq->first_flusher = &this_flusher;
|
|
|
|
if (!flush_workqueue_prep_cwqs(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 */
|
|
BUG_ON(wq->flush_color == this_flusher.flush_color);
|
|
list_add_tail(&this_flusher.list, &wq->flusher_queue);
|
|
flush_workqueue_prep_cwqs(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->flush_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->flush_mutex);
|
|
|
|
/* we might have raced, check again with mutex held */
|
|
if (wq->first_flusher != &this_flusher)
|
|
goto out_unlock;
|
|
|
|
wq->first_flusher = NULL;
|
|
|
|
BUG_ON(!list_empty(&this_flusher.list));
|
|
BUG_ON(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);
|
|
}
|
|
|
|
BUG_ON(!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_cwqs(wq, -1, wq->work_color);
|
|
}
|
|
|
|
if (list_empty(&wq->flusher_queue)) {
|
|
BUG_ON(wq->flush_color != wq->work_color);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Need to flush more colors. Make the next flusher
|
|
* the new first flusher and arm cwqs.
|
|
*/
|
|
BUG_ON(wq->flush_color == wq->work_color);
|
|
BUG_ON(wq->flush_color != next->flush_color);
|
|
|
|
list_del_init(&next->list);
|
|
wq->first_flusher = next;
|
|
|
|
if (flush_workqueue_prep_cwqs(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->flush_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;
|
|
unsigned int cpu;
|
|
|
|
/*
|
|
* __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.
|
|
*/
|
|
spin_lock(&workqueue_lock);
|
|
if (!wq->nr_drainers++)
|
|
wq->flags |= WQ_DRAINING;
|
|
spin_unlock(&workqueue_lock);
|
|
reflush:
|
|
flush_workqueue(wq);
|
|
|
|
for_each_cwq_cpu(cpu, wq) {
|
|
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
|
|
bool drained;
|
|
|
|
spin_lock_irq(&cwq->pool->gcwq->lock);
|
|
drained = !cwq->nr_active && list_empty(&cwq->delayed_works);
|
|
spin_unlock_irq(&cwq->pool->gcwq->lock);
|
|
|
|
if (drained)
|
|
continue;
|
|
|
|
if (++flush_cnt == 10 ||
|
|
(flush_cnt % 100 == 0 && flush_cnt <= 1000))
|
|
pr_warning("workqueue %s: flush on destruction isn't complete after %u tries\n",
|
|
wq->name, flush_cnt);
|
|
goto reflush;
|
|
}
|
|
|
|
spin_lock(&workqueue_lock);
|
|
if (!--wq->nr_drainers)
|
|
wq->flags &= ~WQ_DRAINING;
|
|
spin_unlock(&workqueue_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(drain_workqueue);
|
|
|
|
static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr,
|
|
bool wait_executing)
|
|
{
|
|
struct worker *worker = NULL;
|
|
struct global_cwq *gcwq;
|
|
struct cpu_workqueue_struct *cwq;
|
|
|
|
might_sleep();
|
|
gcwq = get_work_gcwq(work);
|
|
if (!gcwq)
|
|
return false;
|
|
|
|
spin_lock_irq(&gcwq->lock);
|
|
if (!list_empty(&work->entry)) {
|
|
/*
|
|
* See the comment near try_to_grab_pending()->smp_rmb().
|
|
* If it was re-queued to a different gcwq under us, we
|
|
* are not going to wait.
|
|
*/
|
|
smp_rmb();
|
|
cwq = get_work_cwq(work);
|
|
if (unlikely(!cwq || gcwq != cwq->pool->gcwq))
|
|
goto already_gone;
|
|
} else if (wait_executing) {
|
|
worker = find_worker_executing_work(gcwq, work);
|
|
if (!worker)
|
|
goto already_gone;
|
|
cwq = worker->current_cwq;
|
|
} else
|
|
goto already_gone;
|
|
|
|
insert_wq_barrier(cwq, barr, work, worker);
|
|
spin_unlock_irq(&gcwq->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 (cwq->wq->saved_max_active == 1 || cwq->wq->flags & WQ_RESCUER)
|
|
lock_map_acquire(&cwq->wq->lockdep_map);
|
|
else
|
|
lock_map_acquire_read(&cwq->wq->lockdep_map);
|
|
lock_map_release(&cwq->wq->lockdep_map);
|
|
|
|
return true;
|
|
already_gone:
|
|
spin_unlock_irq(&gcwq->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. This function considers
|
|
* only the last queueing instance of @work. If @work has been
|
|
* enqueued across different CPUs on a non-reentrant workqueue or on
|
|
* multiple workqueues, @work might still be executing on return on
|
|
* some of the CPUs from earlier queueing.
|
|
*
|
|
* If @work was queued only on a non-reentrant, ordered or unbound
|
|
* workqueue, @work is guaranteed to be idle on return if it hasn't
|
|
* been requeued since flush started.
|
|
*
|
|
* RETURNS:
|
|
* %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, true)) {
|
|
wait_for_completion(&barr.done);
|
|
destroy_work_on_stack(&barr.work);
|
|
return true;
|
|
} else
|
|
return false;
|
|
}
|
|
EXPORT_SYMBOL_GPL(flush_work);
|
|
|
|
static bool wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work)
|
|
{
|
|
struct wq_barrier barr;
|
|
struct worker *worker;
|
|
|
|
spin_lock_irq(&gcwq->lock);
|
|
|
|
worker = find_worker_executing_work(gcwq, work);
|
|
if (unlikely(worker))
|
|
insert_wq_barrier(worker->current_cwq, &barr, work, worker);
|
|
|
|
spin_unlock_irq(&gcwq->lock);
|
|
|
|
if (unlikely(worker)) {
|
|
wait_for_completion(&barr.done);
|
|
destroy_work_on_stack(&barr.work);
|
|
return true;
|
|
} else
|
|
return false;
|
|
}
|
|
|
|
static bool wait_on_work(struct work_struct *work)
|
|
{
|
|
bool ret = false;
|
|
int cpu;
|
|
|
|
might_sleep();
|
|
|
|
lock_map_acquire(&work->lockdep_map);
|
|
lock_map_release(&work->lockdep_map);
|
|
|
|
for_each_gcwq_cpu(cpu)
|
|
ret |= wait_on_cpu_work(get_gcwq(cpu), work);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* flush_work_sync - wait until a work has finished execution
|
|
* @work: the work to flush
|
|
*
|
|
* Wait until @work has finished execution. On return, it's
|
|
* guaranteed that all queueing instances of @work which happened
|
|
* before this function is called are finished. In other words, if
|
|
* @work hasn't been requeued since this function was called, @work is
|
|
* guaranteed to be idle on return.
|
|
*
|
|
* RETURNS:
|
|
* %true if flush_work_sync() waited for the work to finish execution,
|
|
* %false if it was already idle.
|
|
*/
|
|
bool flush_work_sync(struct work_struct *work)
|
|
{
|
|
struct wq_barrier barr;
|
|
bool pending, waited;
|
|
|
|
/* we'll wait for executions separately, queue barr only if pending */
|
|
pending = start_flush_work(work, &barr, false);
|
|
|
|
/* wait for executions to finish */
|
|
waited = wait_on_work(work);
|
|
|
|
/* wait for the pending one */
|
|
if (pending) {
|
|
wait_for_completion(&barr.done);
|
|
destroy_work_on_stack(&barr.work);
|
|
}
|
|
|
|
return pending || waited;
|
|
}
|
|
EXPORT_SYMBOL_GPL(flush_work_sync);
|
|
|
|
/*
|
|
* Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
|
|
* so this work can't be re-armed in any way.
|
|
*/
|
|
static int try_to_grab_pending(struct work_struct *work)
|
|
{
|
|
struct global_cwq *gcwq;
|
|
int ret = -1;
|
|
|
|
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.
|
|
*/
|
|
gcwq = get_work_gcwq(work);
|
|
if (!gcwq)
|
|
return ret;
|
|
|
|
spin_lock_irq(&gcwq->lock);
|
|
if (!list_empty(&work->entry)) {
|
|
/*
|
|
* This work is queued, but perhaps we locked the wrong gcwq.
|
|
* In that case we must see the new value after rmb(), see
|
|
* insert_work()->wmb().
|
|
*/
|
|
smp_rmb();
|
|
if (gcwq == get_work_gcwq(work)) {
|
|
debug_work_deactivate(work);
|
|
list_del_init(&work->entry);
|
|
cwq_dec_nr_in_flight(get_work_cwq(work),
|
|
get_work_color(work),
|
|
*work_data_bits(work) & WORK_STRUCT_DELAYED);
|
|
ret = 1;
|
|
}
|
|
}
|
|
spin_unlock_irq(&gcwq->lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static bool __cancel_work_timer(struct work_struct *work,
|
|
struct timer_list* timer)
|
|
{
|
|
int ret;
|
|
|
|
do {
|
|
ret = (timer && likely(del_timer(timer)));
|
|
if (!ret)
|
|
ret = try_to_grab_pending(work);
|
|
wait_on_work(work);
|
|
} while (unlikely(ret < 0));
|
|
|
|
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.
|
|
*
|
|
* RETURNS:
|
|
* %true if @work was pending, %false otherwise.
|
|
*/
|
|
bool cancel_work_sync(struct work_struct *work)
|
|
{
|
|
return __cancel_work_timer(work, NULL);
|
|
}
|
|
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.
|
|
*
|
|
* RETURNS:
|
|
* %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)
|
|
{
|
|
if (del_timer_sync(&dwork->timer))
|
|
__queue_work(raw_smp_processor_id(),
|
|
get_work_cwq(&dwork->work)->wq, &dwork->work);
|
|
return flush_work(&dwork->work);
|
|
}
|
|
EXPORT_SYMBOL(flush_delayed_work);
|
|
|
|
/**
|
|
* flush_delayed_work_sync - wait for a dwork to finish
|
|
* @dwork: the delayed work to flush
|
|
*
|
|
* Delayed timer is cancelled and the pending work is queued for
|
|
* execution immediately. Other than timer handling, its behavior
|
|
* is identical to flush_work_sync().
|
|
*
|
|
* RETURNS:
|
|
* %true if flush_work_sync() waited for the work to finish execution,
|
|
* %false if it was already idle.
|
|
*/
|
|
bool flush_delayed_work_sync(struct delayed_work *dwork)
|
|
{
|
|
if (del_timer_sync(&dwork->timer))
|
|
__queue_work(raw_smp_processor_id(),
|
|
get_work_cwq(&dwork->work)->wq, &dwork->work);
|
|
return flush_work_sync(&dwork->work);
|
|
}
|
|
EXPORT_SYMBOL(flush_delayed_work_sync);
|
|
|
|
/**
|
|
* 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.
|
|
*
|
|
* RETURNS:
|
|
* %true if @dwork was pending, %false otherwise.
|
|
*/
|
|
bool cancel_delayed_work_sync(struct delayed_work *dwork)
|
|
{
|
|
return __cancel_work_timer(&dwork->work, &dwork->timer);
|
|
}
|
|
EXPORT_SYMBOL(cancel_delayed_work_sync);
|
|
|
|
/**
|
|
* schedule_work - put work task in global workqueue
|
|
* @work: job to be done
|
|
*
|
|
* Returns zero if @work was already on the kernel-global workqueue and
|
|
* non-zero otherwise.
|
|
*
|
|
* This puts a job in the kernel-global workqueue if it was not already
|
|
* queued and leaves it in the same position on the kernel-global
|
|
* workqueue otherwise.
|
|
*/
|
|
int schedule_work(struct work_struct *work)
|
|
{
|
|
return queue_work(system_wq, work);
|
|
}
|
|
EXPORT_SYMBOL(schedule_work);
|
|
|
|
/*
|
|
* schedule_work_on - put work task on a specific cpu
|
|
* @cpu: cpu to put the work task on
|
|
* @work: job to be done
|
|
*
|
|
* This puts a job on a specific cpu
|
|
*/
|
|
int schedule_work_on(int cpu, struct work_struct *work)
|
|
{
|
|
return queue_work_on(cpu, system_wq, work);
|
|
}
|
|
EXPORT_SYMBOL(schedule_work_on);
|
|
|
|
/**
|
|
* schedule_delayed_work - put work task in global workqueue after delay
|
|
* @dwork: job to be done
|
|
* @delay: number of jiffies to wait or 0 for immediate execution
|
|
*
|
|
* After waiting for a given time this puts a job in the kernel-global
|
|
* workqueue.
|
|
*/
|
|
int schedule_delayed_work(struct delayed_work *dwork,
|
|
unsigned long delay)
|
|
{
|
|
return queue_delayed_work(system_wq, dwork, delay);
|
|
}
|
|
EXPORT_SYMBOL(schedule_delayed_work);
|
|
|
|
/**
|
|
* schedule_delayed_work_on - queue work in global workqueue on CPU after delay
|
|
* @cpu: cpu to use
|
|
* @dwork: job to be done
|
|
* @delay: number of jiffies to wait
|
|
*
|
|
* After waiting for a given time this puts a job in the kernel-global
|
|
* workqueue on the specified CPU.
|
|
*/
|
|
int schedule_delayed_work_on(int cpu,
|
|
struct delayed_work *dwork, unsigned long delay)
|
|
{
|
|
return queue_delayed_work_on(cpu, system_wq, dwork, delay);
|
|
}
|
|
EXPORT_SYMBOL(schedule_delayed_work_on);
|
|
|
|
/**
|
|
* 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.
|
|
*
|
|
* RETURNS:
|
|
* 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.
|
|
*
|
|
* Returns: 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);
|
|
|
|
int keventd_up(void)
|
|
{
|
|
return system_wq != NULL;
|
|
}
|
|
|
|
static int alloc_cwqs(struct workqueue_struct *wq)
|
|
{
|
|
/*
|
|
* cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
|
|
* Make sure that the alignment isn't lower than that of
|
|
* unsigned long long.
|
|
*/
|
|
const size_t size = sizeof(struct cpu_workqueue_struct);
|
|
const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS,
|
|
__alignof__(unsigned long long));
|
|
|
|
if (!(wq->flags & WQ_UNBOUND))
|
|
wq->cpu_wq.pcpu = __alloc_percpu(size, align);
|
|
else {
|
|
void *ptr;
|
|
|
|
/*
|
|
* Allocate enough room to align cwq and put an extra
|
|
* pointer at the end pointing back to the originally
|
|
* allocated pointer which will be used for free.
|
|
*/
|
|
ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL);
|
|
if (ptr) {
|
|
wq->cpu_wq.single = PTR_ALIGN(ptr, align);
|
|
*(void **)(wq->cpu_wq.single + 1) = ptr;
|
|
}
|
|
}
|
|
|
|
/* just in case, make sure it's actually aligned */
|
|
BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align));
|
|
return wq->cpu_wq.v ? 0 : -ENOMEM;
|
|
}
|
|
|
|
static void free_cwqs(struct workqueue_struct *wq)
|
|
{
|
|
if (!(wq->flags & WQ_UNBOUND))
|
|
free_percpu(wq->cpu_wq.pcpu);
|
|
else if (wq->cpu_wq.single) {
|
|
/* the pointer to free is stored right after the cwq */
|
|
kfree(*(void **)(wq->cpu_wq.single + 1));
|
|
}
|
|
}
|
|
|
|
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)
|
|
printk(KERN_WARNING "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, ...)
|
|
{
|
|
va_list args, args1;
|
|
struct workqueue_struct *wq;
|
|
unsigned int cpu;
|
|
size_t namelen;
|
|
|
|
/* determine namelen, allocate wq and format name */
|
|
va_start(args, lock_name);
|
|
va_copy(args1, args);
|
|
namelen = vsnprintf(NULL, 0, fmt, args) + 1;
|
|
|
|
wq = kzalloc(sizeof(*wq) + namelen, GFP_KERNEL);
|
|
if (!wq)
|
|
goto err;
|
|
|
|
vsnprintf(wq->name, namelen, fmt, args1);
|
|
va_end(args);
|
|
va_end(args1);
|
|
|
|
/*
|
|
* Workqueues which may be used during memory reclaim should
|
|
* have a rescuer to guarantee forward progress.
|
|
*/
|
|
if (flags & WQ_MEM_RECLAIM)
|
|
flags |= WQ_RESCUER;
|
|
|
|
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->flush_mutex);
|
|
atomic_set(&wq->nr_cwqs_to_flush, 0);
|
|
INIT_LIST_HEAD(&wq->flusher_queue);
|
|
INIT_LIST_HEAD(&wq->flusher_overflow);
|
|
|
|
lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
|
|
INIT_LIST_HEAD(&wq->list);
|
|
|
|
if (alloc_cwqs(wq) < 0)
|
|
goto err;
|
|
|
|
for_each_cwq_cpu(cpu, wq) {
|
|
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
|
|
struct global_cwq *gcwq = get_gcwq(cpu);
|
|
int pool_idx = (bool)(flags & WQ_HIGHPRI);
|
|
|
|
BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK);
|
|
cwq->pool = &gcwq->pools[pool_idx];
|
|
cwq->wq = wq;
|
|
cwq->flush_color = -1;
|
|
cwq->max_active = max_active;
|
|
INIT_LIST_HEAD(&cwq->delayed_works);
|
|
}
|
|
|
|
if (flags & WQ_RESCUER) {
|
|
struct worker *rescuer;
|
|
|
|
if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL))
|
|
goto err;
|
|
|
|
wq->rescuer = rescuer = alloc_worker();
|
|
if (!rescuer)
|
|
goto err;
|
|
|
|
rescuer->task = kthread_create(rescuer_thread, wq, "%s",
|
|
wq->name);
|
|
if (IS_ERR(rescuer->task))
|
|
goto err;
|
|
|
|
rescuer->task->flags |= PF_THREAD_BOUND;
|
|
wake_up_process(rescuer->task);
|
|
}
|
|
|
|
/*
|
|
* workqueue_lock protects global freeze state and workqueues
|
|
* list. Grab it, set max_active accordingly and add the new
|
|
* workqueue to workqueues list.
|
|
*/
|
|
spin_lock(&workqueue_lock);
|
|
|
|
if (workqueue_freezing && wq->flags & WQ_FREEZABLE)
|
|
for_each_cwq_cpu(cpu, wq)
|
|
get_cwq(cpu, wq)->max_active = 0;
|
|
|
|
list_add(&wq->list, &workqueues);
|
|
|
|
spin_unlock(&workqueue_lock);
|
|
|
|
return wq;
|
|
err:
|
|
if (wq) {
|
|
free_cwqs(wq);
|
|
free_mayday_mask(wq->mayday_mask);
|
|
kfree(wq->rescuer);
|
|
kfree(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)
|
|
{
|
|
unsigned int cpu;
|
|
|
|
/* drain it before proceeding with destruction */
|
|
drain_workqueue(wq);
|
|
|
|
/*
|
|
* wq list is used to freeze wq, remove from list after
|
|
* flushing is complete in case freeze races us.
|
|
*/
|
|
spin_lock(&workqueue_lock);
|
|
list_del(&wq->list);
|
|
spin_unlock(&workqueue_lock);
|
|
|
|
/* sanity check */
|
|
for_each_cwq_cpu(cpu, wq) {
|
|
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
|
|
int i;
|
|
|
|
for (i = 0; i < WORK_NR_COLORS; i++)
|
|
BUG_ON(cwq->nr_in_flight[i]);
|
|
BUG_ON(cwq->nr_active);
|
|
BUG_ON(!list_empty(&cwq->delayed_works));
|
|
}
|
|
|
|
if (wq->flags & WQ_RESCUER) {
|
|
kthread_stop(wq->rescuer->task);
|
|
free_mayday_mask(wq->mayday_mask);
|
|
kfree(wq->rescuer);
|
|
}
|
|
|
|
free_cwqs(wq);
|
|
kfree(wq);
|
|
}
|
|
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)
|
|
{
|
|
unsigned int cpu;
|
|
|
|
max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
|
|
|
|
spin_lock(&workqueue_lock);
|
|
|
|
wq->saved_max_active = max_active;
|
|
|
|
for_each_cwq_cpu(cpu, wq) {
|
|
struct global_cwq *gcwq = get_gcwq(cpu);
|
|
|
|
spin_lock_irq(&gcwq->lock);
|
|
|
|
if (!(wq->flags & WQ_FREEZABLE) ||
|
|
!(gcwq->flags & GCWQ_FREEZING))
|
|
get_cwq(gcwq->cpu, wq)->max_active = max_active;
|
|
|
|
spin_unlock_irq(&gcwq->lock);
|
|
}
|
|
|
|
spin_unlock(&workqueue_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(workqueue_set_max_active);
|
|
|
|
/**
|
|
* 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.
|
|
*
|
|
* RETURNS:
|
|
* %true if congested, %false otherwise.
|
|
*/
|
|
bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq)
|
|
{
|
|
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
|
|
|
|
return !list_empty(&cwq->delayed_works);
|
|
}
|
|
EXPORT_SYMBOL_GPL(workqueue_congested);
|
|
|
|
/**
|
|
* work_cpu - return the last known associated cpu for @work
|
|
* @work: the work of interest
|
|
*
|
|
* RETURNS:
|
|
* CPU number if @work was ever queued. WORK_CPU_NONE otherwise.
|
|
*/
|
|
unsigned int work_cpu(struct work_struct *work)
|
|
{
|
|
struct global_cwq *gcwq = get_work_gcwq(work);
|
|
|
|
return gcwq ? gcwq->cpu : WORK_CPU_NONE;
|
|
}
|
|
EXPORT_SYMBOL_GPL(work_cpu);
|
|
|
|
/**
|
|
* 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.
|
|
* Especially for reentrant wqs, the pending state might hide the
|
|
* running state.
|
|
*
|
|
* RETURNS:
|
|
* OR'd bitmask of WORK_BUSY_* bits.
|
|
*/
|
|
unsigned int work_busy(struct work_struct *work)
|
|
{
|
|
struct global_cwq *gcwq = get_work_gcwq(work);
|
|
unsigned long flags;
|
|
unsigned int ret = 0;
|
|
|
|
if (!gcwq)
|
|
return false;
|
|
|
|
spin_lock_irqsave(&gcwq->lock, flags);
|
|
|
|
if (work_pending(work))
|
|
ret |= WORK_BUSY_PENDING;
|
|
if (find_worker_executing_work(gcwq, work))
|
|
ret |= WORK_BUSY_RUNNING;
|
|
|
|
spin_unlock_irqrestore(&gcwq->lock, flags);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(work_busy);
|
|
|
|
/*
|
|
* CPU hotplug.
|
|
*
|
|
* There are two challenges in supporting CPU hotplug. Firstly, there
|
|
* are a lot of assumptions on strong associations among work, cwq and
|
|
* gcwq which make migrating pending and scheduled works very
|
|
* difficult to implement without impacting hot paths. Secondly,
|
|
* gcwqs serve mix of short, long and very long running works making
|
|
* blocked draining impractical.
|
|
*
|
|
* This is solved by allowing a gcwq to be disassociated from the CPU
|
|
* running as an unbound one and allowing it to be reattached later if the
|
|
* cpu comes back online.
|
|
*/
|
|
|
|
/* claim manager positions of all pools */
|
|
static void gcwq_claim_management_and_lock(struct global_cwq *gcwq)
|
|
{
|
|
struct worker_pool *pool;
|
|
|
|
for_each_worker_pool(pool, gcwq)
|
|
mutex_lock_nested(&pool->manager_mutex, pool - gcwq->pools);
|
|
spin_lock_irq(&gcwq->lock);
|
|
}
|
|
|
|
/* release manager positions */
|
|
static void gcwq_release_management_and_unlock(struct global_cwq *gcwq)
|
|
{
|
|
struct worker_pool *pool;
|
|
|
|
spin_unlock_irq(&gcwq->lock);
|
|
for_each_worker_pool(pool, gcwq)
|
|
mutex_unlock(&pool->manager_mutex);
|
|
}
|
|
|
|
static void gcwq_unbind_fn(struct work_struct *work)
|
|
{
|
|
struct global_cwq *gcwq = get_gcwq(smp_processor_id());
|
|
struct worker_pool *pool;
|
|
struct worker *worker;
|
|
struct hlist_node *pos;
|
|
int i;
|
|
|
|
BUG_ON(gcwq->cpu != smp_processor_id());
|
|
|
|
gcwq_claim_management_and_lock(gcwq);
|
|
|
|
/*
|
|
* We've claimed all manager positions. 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_worker_pool(pool, gcwq)
|
|
list_for_each_entry(worker, &pool->idle_list, entry)
|
|
worker->flags |= WORKER_UNBOUND;
|
|
|
|
for_each_busy_worker(worker, i, pos, gcwq)
|
|
worker->flags |= WORKER_UNBOUND;
|
|
|
|
gcwq->flags |= GCWQ_DISASSOCIATED;
|
|
|
|
gcwq_release_management_and_unlock(gcwq);
|
|
|
|
/*
|
|
* 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. @gcwq now
|
|
* behaves as unbound (in terms of concurrency management) gcwq
|
|
* which is served by workers tied to the CPU.
|
|
*
|
|
* On return from this function, the current worker would trigger
|
|
* unbound chain execution of pending work items if other workers
|
|
* didn't already.
|
|
*/
|
|
for_each_worker_pool(pool, gcwq)
|
|
atomic_set(get_pool_nr_running(pool), 0);
|
|
}
|
|
|
|
/*
|
|
* Workqueues should be brought up before normal priority CPU notifiers.
|
|
* This will be registered high priority CPU notifier.
|
|
*/
|
|
static int __devinit workqueue_cpu_up_callback(struct notifier_block *nfb,
|
|
unsigned long action,
|
|
void *hcpu)
|
|
{
|
|
unsigned int cpu = (unsigned long)hcpu;
|
|
struct global_cwq *gcwq = get_gcwq(cpu);
|
|
struct worker_pool *pool;
|
|
|
|
switch (action & ~CPU_TASKS_FROZEN) {
|
|
case CPU_UP_PREPARE:
|
|
for_each_worker_pool(pool, gcwq) {
|
|
struct worker *worker;
|
|
|
|
if (pool->nr_workers)
|
|
continue;
|
|
|
|
worker = create_worker(pool);
|
|
if (!worker)
|
|
return NOTIFY_BAD;
|
|
|
|
spin_lock_irq(&gcwq->lock);
|
|
start_worker(worker);
|
|
spin_unlock_irq(&gcwq->lock);
|
|
}
|
|
break;
|
|
|
|
case CPU_DOWN_FAILED:
|
|
case CPU_ONLINE:
|
|
gcwq_claim_management_and_lock(gcwq);
|
|
gcwq->flags &= ~GCWQ_DISASSOCIATED;
|
|
rebind_workers(gcwq);
|
|
gcwq_release_management_and_unlock(gcwq);
|
|
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 __devinit workqueue_cpu_down_callback(struct notifier_block *nfb,
|
|
unsigned long action,
|
|
void *hcpu)
|
|
{
|
|
unsigned int cpu = (unsigned long)hcpu;
|
|
struct work_struct unbind_work;
|
|
|
|
switch (action & ~CPU_TASKS_FROZEN) {
|
|
case CPU_DOWN_PREPARE:
|
|
/* unbinding should happen on the local CPU */
|
|
INIT_WORK_ONSTACK(&unbind_work, gcwq_unbind_fn);
|
|
schedule_work_on(cpu, &unbind_work);
|
|
flush_work(&unbind_work);
|
|
break;
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
struct work_for_cpu {
|
|
struct completion completion;
|
|
long (*fn)(void *);
|
|
void *arg;
|
|
long ret;
|
|
};
|
|
|
|
static int do_work_for_cpu(void *_wfc)
|
|
{
|
|
struct work_for_cpu *wfc = _wfc;
|
|
wfc->ret = wfc->fn(wfc->arg);
|
|
complete(&wfc->completion);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* 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
|
|
*
|
|
* This will return the value @fn returns.
|
|
* 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.
|
|
*/
|
|
long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
|
|
{
|
|
struct task_struct *sub_thread;
|
|
struct work_for_cpu wfc = {
|
|
.completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion),
|
|
.fn = fn,
|
|
.arg = arg,
|
|
};
|
|
|
|
sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu");
|
|
if (IS_ERR(sub_thread))
|
|
return PTR_ERR(sub_thread);
|
|
kthread_bind(sub_thread, cpu);
|
|
wake_up_process(sub_thread);
|
|
wait_for_completion(&wfc.completion);
|
|
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 frozen_works list instead of
|
|
* gcwq->worklist.
|
|
*
|
|
* CONTEXT:
|
|
* Grabs and releases workqueue_lock and gcwq->lock's.
|
|
*/
|
|
void freeze_workqueues_begin(void)
|
|
{
|
|
unsigned int cpu;
|
|
|
|
spin_lock(&workqueue_lock);
|
|
|
|
BUG_ON(workqueue_freezing);
|
|
workqueue_freezing = true;
|
|
|
|
for_each_gcwq_cpu(cpu) {
|
|
struct global_cwq *gcwq = get_gcwq(cpu);
|
|
struct workqueue_struct *wq;
|
|
|
|
spin_lock_irq(&gcwq->lock);
|
|
|
|
BUG_ON(gcwq->flags & GCWQ_FREEZING);
|
|
gcwq->flags |= GCWQ_FREEZING;
|
|
|
|
list_for_each_entry(wq, &workqueues, list) {
|
|
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
|
|
|
|
if (cwq && wq->flags & WQ_FREEZABLE)
|
|
cwq->max_active = 0;
|
|
}
|
|
|
|
spin_unlock_irq(&gcwq->lock);
|
|
}
|
|
|
|
spin_unlock(&workqueue_lock);
|
|
}
|
|
|
|
/**
|
|
* 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 workqueue_lock.
|
|
*
|
|
* RETURNS:
|
|
* %true if some freezable workqueues are still busy. %false if freezing
|
|
* is complete.
|
|
*/
|
|
bool freeze_workqueues_busy(void)
|
|
{
|
|
unsigned int cpu;
|
|
bool busy = false;
|
|
|
|
spin_lock(&workqueue_lock);
|
|
|
|
BUG_ON(!workqueue_freezing);
|
|
|
|
for_each_gcwq_cpu(cpu) {
|
|
struct workqueue_struct *wq;
|
|
/*
|
|
* nr_active is monotonically decreasing. It's safe
|
|
* to peek without lock.
|
|
*/
|
|
list_for_each_entry(wq, &workqueues, list) {
|
|
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
|
|
|
|
if (!cwq || !(wq->flags & WQ_FREEZABLE))
|
|
continue;
|
|
|
|
BUG_ON(cwq->nr_active < 0);
|
|
if (cwq->nr_active) {
|
|
busy = true;
|
|
goto out_unlock;
|
|
}
|
|
}
|
|
}
|
|
out_unlock:
|
|
spin_unlock(&workqueue_lock);
|
|
return busy;
|
|
}
|
|
|
|
/**
|
|
* thaw_workqueues - thaw workqueues
|
|
*
|
|
* Thaw workqueues. Normal queueing is restored and all collected
|
|
* frozen works are transferred to their respective gcwq worklists.
|
|
*
|
|
* CONTEXT:
|
|
* Grabs and releases workqueue_lock and gcwq->lock's.
|
|
*/
|
|
void thaw_workqueues(void)
|
|
{
|
|
unsigned int cpu;
|
|
|
|
spin_lock(&workqueue_lock);
|
|
|
|
if (!workqueue_freezing)
|
|
goto out_unlock;
|
|
|
|
for_each_gcwq_cpu(cpu) {
|
|
struct global_cwq *gcwq = get_gcwq(cpu);
|
|
struct worker_pool *pool;
|
|
struct workqueue_struct *wq;
|
|
|
|
spin_lock_irq(&gcwq->lock);
|
|
|
|
BUG_ON(!(gcwq->flags & GCWQ_FREEZING));
|
|
gcwq->flags &= ~GCWQ_FREEZING;
|
|
|
|
list_for_each_entry(wq, &workqueues, list) {
|
|
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
|
|
|
|
if (!cwq || !(wq->flags & WQ_FREEZABLE))
|
|
continue;
|
|
|
|
/* restore max_active and repopulate worklist */
|
|
cwq->max_active = wq->saved_max_active;
|
|
|
|
while (!list_empty(&cwq->delayed_works) &&
|
|
cwq->nr_active < cwq->max_active)
|
|
cwq_activate_first_delayed(cwq);
|
|
}
|
|
|
|
for_each_worker_pool(pool, gcwq)
|
|
wake_up_worker(pool);
|
|
|
|
spin_unlock_irq(&gcwq->lock);
|
|
}
|
|
|
|
workqueue_freezing = false;
|
|
out_unlock:
|
|
spin_unlock(&workqueue_lock);
|
|
}
|
|
#endif /* CONFIG_FREEZER */
|
|
|
|
static int __init init_workqueues(void)
|
|
{
|
|
unsigned int cpu;
|
|
int i;
|
|
|
|
cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP);
|
|
cpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN);
|
|
|
|
/* initialize gcwqs */
|
|
for_each_gcwq_cpu(cpu) {
|
|
struct global_cwq *gcwq = get_gcwq(cpu);
|
|
struct worker_pool *pool;
|
|
|
|
spin_lock_init(&gcwq->lock);
|
|
gcwq->cpu = cpu;
|
|
gcwq->flags |= GCWQ_DISASSOCIATED;
|
|
|
|
for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)
|
|
INIT_HLIST_HEAD(&gcwq->busy_hash[i]);
|
|
|
|
for_each_worker_pool(pool, gcwq) {
|
|
pool->gcwq = gcwq;
|
|
INIT_LIST_HEAD(&pool->worklist);
|
|
INIT_LIST_HEAD(&pool->idle_list);
|
|
|
|
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, gcwq_mayday_timeout,
|
|
(unsigned long)pool);
|
|
|
|
mutex_init(&pool->manager_mutex);
|
|
ida_init(&pool->worker_ida);
|
|
}
|
|
|
|
init_waitqueue_head(&gcwq->rebind_hold);
|
|
}
|
|
|
|
/* create the initial worker */
|
|
for_each_online_gcwq_cpu(cpu) {
|
|
struct global_cwq *gcwq = get_gcwq(cpu);
|
|
struct worker_pool *pool;
|
|
|
|
if (cpu != WORK_CPU_UNBOUND)
|
|
gcwq->flags &= ~GCWQ_DISASSOCIATED;
|
|
|
|
for_each_worker_pool(pool, gcwq) {
|
|
struct worker *worker;
|
|
|
|
worker = create_worker(pool);
|
|
BUG_ON(!worker);
|
|
spin_lock_irq(&gcwq->lock);
|
|
start_worker(worker);
|
|
spin_unlock_irq(&gcwq->lock);
|
|
}
|
|
}
|
|
|
|
system_wq = alloc_workqueue("events", 0, 0);
|
|
system_long_wq = alloc_workqueue("events_long", 0, 0);
|
|
system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 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_nrt_freezable_wq = alloc_workqueue("events_nrt_freezable",
|
|
WQ_NON_REENTRANT | WQ_FREEZABLE, 0);
|
|
BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq ||
|
|
!system_unbound_wq || !system_freezable_wq ||
|
|
!system_nrt_freezable_wq);
|
|
return 0;
|
|
}
|
|
early_initcall(init_workqueues);
|