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ce81355231
commit 38d589f2fd upstream.
With the ultimate goal of keeping rt_mutex wait_list and futex_q waiters
consistent it's necessary to split 'rt_mutex_futex_lock()' into finer
parts, such that only the actual blocking can be done without hb->lock
held.
Split split_mutex_finish_proxy_lock() into two parts, one that does the
blocking and one that does remove_waiter() when the lock acquire failed.
When the rtmutex was acquired successfully the waiter can be removed in the
acquisiton path safely, since there is no concurrency on the lock owner.
This means that, except for futex_lock_pi(), all wait_list modifications
are done with both hb->lock and wait_lock held.
[bigeasy@linutronix.de: fix for futex_requeue_pi_signal_restart]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: juri.lelli@arm.com
Cc: bigeasy@linutronix.de
Cc: xlpang@redhat.com
Cc: rostedt@goodmis.org
Cc: mathieu.desnoyers@efficios.com
Cc: jdesfossez@efficios.com
Cc: dvhart@infradead.org
Cc: bristot@redhat.com
Link: http://lkml.kernel.org/r/20170322104152.001659630@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Zubin Mithra <zsm@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
126 lines
3.4 KiB
C
126 lines
3.4 KiB
C
/*
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* RT Mutexes: blocking mutual exclusion locks with PI support
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*
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* started by Ingo Molnar and Thomas Gleixner:
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*
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* Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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* Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
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*
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* This file contains the private data structure and API definitions.
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*/
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#ifndef __KERNEL_RTMUTEX_COMMON_H
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#define __KERNEL_RTMUTEX_COMMON_H
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#include <linux/rtmutex.h>
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/*
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* This is the control structure for tasks blocked on a rt_mutex,
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* which is allocated on the kernel stack on of the blocked task.
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*
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* @tree_entry: pi node to enqueue into the mutex waiters tree
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* @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree
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* @task: task reference to the blocked task
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*/
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struct rt_mutex_waiter {
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struct rb_node tree_entry;
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struct rb_node pi_tree_entry;
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struct task_struct *task;
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struct rt_mutex *lock;
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#ifdef CONFIG_DEBUG_RT_MUTEXES
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unsigned long ip;
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struct pid *deadlock_task_pid;
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struct rt_mutex *deadlock_lock;
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#endif
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int prio;
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u64 deadline;
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};
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/*
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* Various helpers to access the waiters-tree:
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*/
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static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
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{
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return !RB_EMPTY_ROOT(&lock->waiters);
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}
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static inline struct rt_mutex_waiter *
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rt_mutex_top_waiter(struct rt_mutex *lock)
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{
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struct rt_mutex_waiter *w;
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w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter,
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tree_entry);
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BUG_ON(w->lock != lock);
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return w;
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}
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static inline int task_has_pi_waiters(struct task_struct *p)
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{
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return !RB_EMPTY_ROOT(&p->pi_waiters);
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}
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static inline struct rt_mutex_waiter *
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task_top_pi_waiter(struct task_struct *p)
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{
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return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter,
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pi_tree_entry);
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}
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/*
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* lock->owner state tracking:
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*/
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#define RT_MUTEX_HAS_WAITERS 1UL
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#define RT_MUTEX_OWNER_MASKALL 1UL
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static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
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{
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unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
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return (struct task_struct *) (owner & ~RT_MUTEX_OWNER_MASKALL);
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}
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/*
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* Constants for rt mutex functions which have a selectable deadlock
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* detection.
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*
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* RT_MUTEX_MIN_CHAINWALK: Stops the lock chain walk when there are
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* no further PI adjustments to be made.
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*
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* RT_MUTEX_FULL_CHAINWALK: Invoke deadlock detection with a full
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* walk of the lock chain.
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*/
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enum rtmutex_chainwalk {
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RT_MUTEX_MIN_CHAINWALK,
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RT_MUTEX_FULL_CHAINWALK,
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};
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/*
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* PI-futex support (proxy locking functions, etc.):
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*/
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extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
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extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
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struct task_struct *proxy_owner);
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extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
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struct task_struct *proxy_owner);
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extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
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struct rt_mutex_waiter *waiter,
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struct task_struct *task);
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extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
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struct hrtimer_sleeper *to,
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struct rt_mutex_waiter *waiter);
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extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
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struct rt_mutex_waiter *waiter);
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extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct hrtimer_sleeper *to);
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extern bool rt_mutex_futex_unlock(struct rt_mutex *lock,
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struct wake_q_head *wqh);
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extern void rt_mutex_adjust_prio(struct task_struct *task);
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#ifdef CONFIG_DEBUG_RT_MUTEXES
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# include "rtmutex-debug.h"
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#else
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# include "rtmutex.h"
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#endif
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#endif
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