Commit 0898678c authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'locking-urgent-2021-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull locking fixes from Thomas Gleixner:
 "Two locking fixes:

   - Invoke the lockdep tracepoints in the correct place so the ordering
     is correct again

   - Don't leave the mutex WAITER bit stale when the last waiter is
     dropping out early due to a signal as that forces all subsequent
     lock operations needlessly into the slowpath until it's cleaned up
     again"

* tag 'locking-urgent-2021-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/mutex: clear MUTEX_FLAGS if wait_list is empty due to signal
  locking/lockdep: Correct calling tracepoints
parents f73d2a42 3a010c49

kernel/locking/lockdep.c

+2 −2
Original line number Diff line number Diff line
@@ -5736,7 +5736,7 @@ void lock_contended(struct lockdep_map *lock, unsigned long ip) 
{

	unsigned long flags;



	trace_lock_acquired(lock, ip);

	trace_lock_contended(lock, ip);



	if (unlikely(!lock_stat || !lockdep_enabled()))

		return;
@@ -5754,7 +5754,7 @@ void lock_acquired(struct lockdep_map *lock, unsigned long ip) 
{

	unsigned long flags;



	trace_lock_contended(lock, ip);

	trace_lock_acquired(lock, ip);



	if (unlikely(!lock_stat || !lockdep_enabled()))

		return;

kernel/locking/mutex-debug.c

+2 −2
Original line number Diff line number Diff line
@@ -57,7 +57,7 @@ void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter, 
	task->blocked_on = waiter;

}



void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,

void debug_mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,

			 struct task_struct *task)

{

	DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
@@ -65,7 +65,7 @@ void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter, 
	DEBUG_LOCKS_WARN_ON(task->blocked_on != waiter);

	task->blocked_on = NULL;



	list_del_init(&waiter->list);

	INIT_LIST_HEAD(&waiter->list);

	waiter->task = NULL;

}

kernel/locking/mutex-debug.h

+1 −1
Original line number Diff line number Diff line
@@ -22,7 +22,7 @@ extern void debug_mutex_free_waiter(struct mutex_waiter *waiter); 
extern void debug_mutex_add_waiter(struct mutex *lock,

				   struct mutex_waiter *waiter,

				   struct task_struct *task);

extern void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,

extern void debug_mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,

				struct task_struct *task);

extern void debug_mutex_unlock(struct mutex *lock);

extern void debug_mutex_init(struct mutex *lock, const char *name,

kernel/locking/mutex.c

+13 −5
Original line number Diff line number Diff line
@@ -194,7 +194,7 @@ static inline bool __mutex_waiter_is_first(struct mutex *lock, struct mutex_wait 
 * Add @waiter to a given location in the lock wait_list and set the

 * FLAG_WAITERS flag if it's the first waiter.

 */

static void __sched

static void

__mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,

		   struct list_head *list)

{
@@ -205,6 +205,16 @@ __mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter, 
		__mutex_set_flag(lock, MUTEX_FLAG_WAITERS);

}



static void

__mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter)

{

	list_del(&waiter->list);

	if (likely(list_empty(&lock->wait_list)))

		__mutex_clear_flag(lock, MUTEX_FLAGS);



	debug_mutex_remove_waiter(lock, waiter, current);

}



/*

 * Give up ownership to a specific task, when @task = NULL, this is equivalent

 * to a regular unlock. Sets PICKUP on a handoff, clears HANDOFF, preserves
@@ -1061,9 +1071,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, 
			__ww_mutex_check_waiters(lock, ww_ctx);

	}



	mutex_remove_waiter(lock, &waiter, current);

	if (likely(list_empty(&lock->wait_list)))

		__mutex_clear_flag(lock, MUTEX_FLAGS);

	__mutex_remove_waiter(lock, &waiter);



	debug_mutex_free_waiter(&waiter);
@@ -1080,7 +1088,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, 


err:

	__set_current_state(TASK_RUNNING);

	mutex_remove_waiter(lock, &waiter, current);

	__mutex_remove_waiter(lock, &waiter);

err_early_kill:

	spin_unlock(&lock->wait_lock);

	debug_mutex_free_waiter(&waiter);

kernel/locking/mutex.h

+1 −3
Original line number Diff line number Diff line
@@ -10,12 +10,10 @@ 
 * !CONFIG_DEBUG_MUTEXES case. Most of them are NOPs:

 */



#define mutex_remove_waiter(lock, waiter, task) \

		__list_del((waiter)->list.prev, (waiter)->list.next)



#define debug_mutex_wake_waiter(lock, waiter)		do { } while (0)

#define debug_mutex_free_waiter(waiter)			do { } while (0)

#define debug_mutex_add_waiter(lock, waiter, ti)	do { } while (0)

#define debug_mutex_remove_waiter(lock, waiter, ti)     do { } while (0)

#define debug_mutex_unlock(lock)			do { } while (0)

#define debug_mutex_init(lock, name, key)		do { } while (0)