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3a010c4932
When a interruptible mutex locker is interrupted by a signal
without acquiring this lock and removed from the wait queue.
if the mutex isn't contended enough to have a waiter
put into the wait queue again, the setting of the WAITER
bit will force mutex locker to go into the slowpath to
acquire the lock every time, so if the wait queue is empty,
the WAITER bit need to be clear.
Fixes: 040a0a3710 ("mutex: Add support for wound/wait style locks")
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Zqiang <qiang.zhang@windriver.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210517034005.30828-1-qiang.zhang@windriver.com
108 lines
2.8 KiB
C
108 lines
2.8 KiB
C
/*
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* kernel/mutex-debug.c
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*
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* Debugging code for mutexes
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*
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* Started by Ingo Molnar:
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*
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* Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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*
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* lock debugging, locking tree, deadlock detection started by:
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*
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* Copyright (C) 2004, LynuxWorks, Inc., Igor Manyilov, Bill Huey
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* Released under the General Public License (GPL).
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*/
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#include <linux/mutex.h>
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#include <linux/delay.h>
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#include <linux/export.h>
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#include <linux/poison.h>
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#include <linux/sched.h>
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#include <linux/spinlock.h>
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#include <linux/kallsyms.h>
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#include <linux/interrupt.h>
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#include <linux/debug_locks.h>
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#include "mutex-debug.h"
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/*
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* Must be called with lock->wait_lock held.
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*/
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void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
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{
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memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
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waiter->magic = waiter;
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INIT_LIST_HEAD(&waiter->list);
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}
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void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
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{
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lockdep_assert_held(&lock->wait_lock);
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DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
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DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
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DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
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}
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void debug_mutex_free_waiter(struct mutex_waiter *waiter)
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{
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DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
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memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
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}
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void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
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struct task_struct *task)
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{
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lockdep_assert_held(&lock->wait_lock);
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/* Mark the current thread as blocked on the lock: */
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task->blocked_on = waiter;
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}
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void debug_mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
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struct task_struct *task)
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{
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DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
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DEBUG_LOCKS_WARN_ON(waiter->task != task);
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DEBUG_LOCKS_WARN_ON(task->blocked_on != waiter);
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task->blocked_on = NULL;
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INIT_LIST_HEAD(&waiter->list);
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waiter->task = NULL;
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}
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void debug_mutex_unlock(struct mutex *lock)
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{
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if (likely(debug_locks)) {
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DEBUG_LOCKS_WARN_ON(lock->magic != lock);
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DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
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}
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}
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void debug_mutex_init(struct mutex *lock, const char *name,
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struct lock_class_key *key)
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{
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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/*
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* Make sure we are not reinitializing a held lock:
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*/
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debug_check_no_locks_freed((void *)lock, sizeof(*lock));
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lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_SLEEP);
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#endif
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lock->magic = lock;
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}
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/***
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* mutex_destroy - mark a mutex unusable
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* @lock: the mutex to be destroyed
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*
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* This function marks the mutex uninitialized, and any subsequent
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* use of the mutex is forbidden. The mutex must not be locked when
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* this function is called.
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*/
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void mutex_destroy(struct mutex *lock)
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{
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DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
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lock->magic = NULL;
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}
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EXPORT_SYMBOL_GPL(mutex_destroy);
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