1 files changed, 98 insertions, 44 deletions

diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 2a1d165b3167..09534628dc01 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -46,8 +46,9 @@
 static void __mutex_init_generic(struct mutex *lock)
 {
 	atomic_long_set(&lock->owner, 0);
-	raw_spin_lock_init(&lock->wait_lock);
-	INIT_LIST_HEAD(&lock->wait_list);
+	scoped_guard (raw_spinlock_init, &lock->wait_lock) {
+		lock->first_waiter = NULL;
+	}
 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
 	osq_lock_init(&lock->osq);
 #endif
@@ -150,6 +151,7 @@ EXPORT_SYMBOL(mutex_init_generic);
  * follow with a __mutex_trylock() before failing.
  */
 static __always_inline bool __mutex_trylock_fast(struct mutex *lock)
+	__cond_acquires(true, lock)
 {
 	unsigned long curr = (unsigned long)current;
 	unsigned long zero = 0UL;
@@ -163,6 +165,7 @@ static __always_inline bool __mutex_trylock_fast(struct mutex *lock)
 }
 
 static __always_inline bool __mutex_unlock_fast(struct mutex *lock)
+	__cond_releases(true, lock)
 {
 	unsigned long curr = (unsigned long)current;
 
@@ -171,7 +174,7 @@ static __always_inline bool __mutex_unlock_fast(struct mutex *lock)
 
 #else /* !CONFIG_DEBUG_LOCK_ALLOC */
 
-void mutex_init_lockep(struct mutex *lock, const char *name, struct lock_class_key *key)
+void mutex_init_lockdep(struct mutex *lock, const char *name, struct lock_class_key *key)
 {
 	__mutex_init_generic(lock);
 
@@ -181,7 +184,7 @@ void mutex_init_lockep(struct mutex *lock, const char *name, struct lock_class_k
 	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
 	lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_SLEEP);
 }
-EXPORT_SYMBOL(mutex_init_lockep);
+EXPORT_SYMBOL(mutex_init_lockdep);
 #endif /* !CONFIG_DEBUG_LOCK_ALLOC */
 
 static inline void __mutex_set_flag(struct mutex *lock, unsigned long flag)
@@ -194,33 +197,58 @@ static inline void __mutex_clear_flag(struct mutex *lock, unsigned long flag)
 	atomic_long_andnot(flag, &lock->owner);
 }
 
-static inline bool __mutex_waiter_is_first(struct mutex *lock, struct mutex_waiter *waiter)
-{
-	return list_first_entry(&lock->wait_list, struct mutex_waiter, list) == waiter;
-}
-
 /*
- * Add @waiter to a given location in the lock wait_list and set the
- * FLAG_WAITERS flag if it's the first waiter.
+ * Add @waiter to the @lock wait_list and set the FLAG_WAITERS flag if it's
+ * the first waiter.
+ *
+ * When @pos, @waiter is added before the waiter indicated by @pos. Otherwise
+ * @waiter will be added to the tail of the list.
  */
 static void
 __mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
-		   struct list_head *list)
+		   struct mutex_waiter *pos)
+	__must_hold(&lock->wait_lock)
 {
+	struct mutex_waiter *first = lock->first_waiter;
+
 	hung_task_set_blocker(lock, BLOCKER_TYPE_MUTEX);
 	debug_mutex_add_waiter(lock, waiter, current);
 
-	list_add_tail(&waiter->list, list);
-	if (__mutex_waiter_is_first(lock, waiter))
-		__mutex_set_flag(lock, MUTEX_FLAG_WAITERS);
+	if (pos) {
+		/*
+		 * Insert @waiter before @pos.
+		 */
+		list_add_tail(&waiter->list, &pos->list);
+		/*
+		 * If @pos == @first, then @waiter will be the new first.
+		 */
+		if (pos == first)
+			lock->first_waiter = waiter;
+		return;
+	}
+
+	if (first) {
+		list_add_tail(&waiter->list, &first->list);
+		return;
+	}
+
+	INIT_LIST_HEAD(&waiter->list);
+	lock->first_waiter = waiter;
+	__mutex_set_flag(lock, MUTEX_FLAG_WAITERS);
 }
 
 static void
 __mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter)
+	__must_hold(&lock->wait_lock)
 {
-	list_del(&waiter->list);
-	if (likely(list_empty(&lock->wait_list)))
+	if (list_empty(&waiter->list)) {
 		__mutex_clear_flag(lock, MUTEX_FLAGS);
+		lock->first_waiter = NULL;
+	} else {
+		if (lock->first_waiter == waiter)
+			lock->first_waiter = list_next_entry(waiter, list);
+		list_del(&waiter->list);
+	}
 
 	debug_mutex_remove_waiter(lock, waiter, current);
 	hung_task_clear_blocker();
@@ -259,7 +287,8 @@ static void __mutex_handoff(struct mutex *lock, struct task_struct *task)
  * We also put the fastpath first in the kernel image, to make sure the
  * branch is predicted by the CPU as default-untaken.
  */
-static void __sched __mutex_lock_slowpath(struct mutex *lock);
+static void __sched __mutex_lock_slowpath(struct mutex *lock)
+	__acquires(lock);
 
 /**
  * mutex_lock - acquire the mutex
@@ -340,7 +369,7 @@ bool ww_mutex_spin_on_owner(struct mutex *lock, struct ww_acquire_ctx *ww_ctx,
 	 * Similarly, stop spinning if we are no longer the
 	 * first waiter.
 	 */
-	if (waiter && !__mutex_waiter_is_first(lock, waiter))
+	if (waiter && data_race(lock->first_waiter != waiter))
 		return false;
 
 	return true;
@@ -525,7 +554,8 @@ mutex_optimistic_spin(struct mutex *lock, struct ww_acquire_ctx *ww_ctx,
 }
 #endif
 
-static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigned long ip);
+static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigned long ip)
+	__releases(lock);
 
 /**
  * mutex_unlock - release the mutex
@@ -565,6 +595,7 @@ EXPORT_SYMBOL(mutex_unlock);
  * of a unlocked mutex is not allowed.
  */
 void __sched ww_mutex_unlock(struct ww_mutex *lock)
+	__no_context_analysis
 {
 	__ww_mutex_unlock(lock);
 	mutex_unlock(&lock->base);
@@ -578,6 +609,7 @@ static __always_inline int __sched
 __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclass,
 		    struct lockdep_map *nest_lock, unsigned long ip,
 		    struct ww_acquire_ctx *ww_ctx, const bool use_ww_ctx)
+	__cond_acquires(0, lock)
 {
 	DEFINE_WAKE_Q(wake_q);
 	struct mutex_waiter waiter;
@@ -645,7 +677,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
 
 	if (!use_ww_ctx) {
 		/* add waiting tasks to the end of the waitqueue (FIFO): */
-		__mutex_add_waiter(lock, &waiter, &lock->wait_list);
+		__mutex_add_waiter(lock, &waiter, NULL);
 	} else {
 		/*
 		 * Add in stamp order, waking up waiters that must kill
@@ -656,6 +688,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
 			goto err_early_kill;
 	}
 
+	raw_spin_lock(&current->blocked_lock);
 	__set_task_blocked_on(current, lock);
 	set_current_state(state);
 	trace_contention_begin(lock, LCB_F_MUTEX);
@@ -669,8 +702,9 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
 		 * the handoff.
 		 */
 		if (__mutex_trylock(lock))
-			goto acquired;
+			break;
 
+		raw_spin_unlock(&current->blocked_lock);
 		/*
 		 * Check for signals and kill conditions while holding
 		 * wait_lock. This ensures the lock cancellation is ordered
@@ -691,14 +725,16 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
 
 		schedule_preempt_disabled();
 
-		first = __mutex_waiter_is_first(lock, &waiter);
+		first = lock->first_waiter == &waiter;
 
+		raw_spin_lock_irqsave(&lock->wait_lock, flags);
+		raw_spin_lock(&current->blocked_lock);
 		/*
 		 * As we likely have been woken up by task
 		 * that has cleared our blocked_on state, re-set
 		 * it to the lock we are trying to acquire.
 		 */
-		set_task_blocked_on(current, lock);
+		__set_task_blocked_on(current, lock);
 		set_current_state(state);
 		/*
 		 * Here we order against unlock; we must either see it change
@@ -709,33 +745,40 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
 			break;
 
 		if (first) {
-			trace_contention_begin(lock, LCB_F_MUTEX | LCB_F_SPIN);
+			bool opt_acquired;
+
 			/*
 			 * mutex_optimistic_spin() can call schedule(), so
-			 * clear blocked on so we don't become unselectable
+			 * we need to release these locks before calling it,
+			 * and clear blocked on so we don't become unselectable
 			 * to run.
 			 */
-			clear_task_blocked_on(current, lock);
-			if (mutex_optimistic_spin(lock, ww_ctx, &waiter))
+			__clear_task_blocked_on(current, lock);
+			raw_spin_unlock(&current->blocked_lock);
+			raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
+
+			trace_contention_begin(lock, LCB_F_MUTEX | LCB_F_SPIN);
+			opt_acquired = mutex_optimistic_spin(lock, ww_ctx, &waiter);
+
+			raw_spin_lock_irqsave(&lock->wait_lock, flags);
+			raw_spin_lock(&current->blocked_lock);
+			__set_task_blocked_on(current, lock);
+
+			if (opt_acquired)
 				break;
-			set_task_blocked_on(current, lock);
 			trace_contention_begin(lock, LCB_F_MUTEX);
 		}
-
-		raw_spin_lock_irqsave(&lock->wait_lock, flags);
 	}
-	raw_spin_lock_irqsave(&lock->wait_lock, flags);
-acquired:
 	__clear_task_blocked_on(current, lock);
 	__set_current_state(TASK_RUNNING);
+	raw_spin_unlock(&current->blocked_lock);
 
 	if (ww_ctx) {
 		/*
 		 * Wound-Wait; we stole the lock (!first_waiter), check the
 		 * waiters as anyone might want to wound us.
 		 */
-		if (!ww_ctx->is_wait_die &&
-		    !__mutex_waiter_is_first(lock, &waiter))
+		if (!ww_ctx->is_wait_die && lock->first_waiter != &waiter)
 			__ww_mutex_check_waiters(lock, ww_ctx, &wake_q);
 	}
 
@@ -756,11 +799,11 @@ skip_wait:
 	return 0;
 
 err:
-	__clear_task_blocked_on(current, lock);
+	clear_task_blocked_on(current, lock);
 	__set_current_state(TASK_RUNNING);
 	__mutex_remove_waiter(lock, &waiter);
 err_early_kill:
-	WARN_ON(__get_task_blocked_on(current));
+	WARN_ON(get_task_blocked_on(current));
 	trace_contention_end(lock, ret);
 	raw_spin_unlock_irqrestore_wake(&lock->wait_lock, flags, &wake_q);
 	debug_mutex_free_waiter(&waiter);
@@ -772,6 +815,7 @@ err_early_kill:
 static int __sched
 __mutex_lock(struct mutex *lock, unsigned int state, unsigned int subclass,
 	     struct lockdep_map *nest_lock, unsigned long ip)
+	__cond_acquires(0, lock)
 {
 	return __mutex_lock_common(lock, state, subclass, nest_lock, ip, NULL, false);
 }
@@ -779,6 +823,7 @@ __mutex_lock(struct mutex *lock, unsigned int state, unsigned int subclass,
 static int __sched
 __ww_mutex_lock(struct mutex *lock, unsigned int state, unsigned int subclass,
 		unsigned long ip, struct ww_acquire_ctx *ww_ctx)
+	__cond_acquires(0, lock)
 {
 	return __mutex_lock_common(lock, state, subclass, NULL, ip, ww_ctx, true);
 }
@@ -826,6 +871,7 @@ void __sched
 mutex_lock_nested(struct mutex *lock, unsigned int subclass)
 {
 	__mutex_lock(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_);
+	__acquire(lock);
 }
 
 EXPORT_SYMBOL_GPL(mutex_lock_nested);
@@ -834,6 +880,7 @@ void __sched
 _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest)
 {
 	__mutex_lock(lock, TASK_UNINTERRUPTIBLE, 0, nest, _RET_IP_);
+	__acquire(lock);
 }
 EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock);
 
@@ -862,12 +909,14 @@ mutex_lock_io_nested(struct mutex *lock, unsigned int subclass)
 	token = io_schedule_prepare();
 	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,
 			    subclass, NULL, _RET_IP_, NULL, 0);
+	__acquire(lock);
 	io_schedule_finish(token);
 }
 EXPORT_SYMBOL_GPL(mutex_lock_io_nested);
 
 static inline int
 ww_mutex_deadlock_injection(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+	__cond_releases(nonzero, lock)
 {
 #ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
 	unsigned tmp;
@@ -929,13 +978,16 @@ EXPORT_SYMBOL_GPL(ww_mutex_lock_interruptible);
  * Release the lock, slowpath:
  */
 static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigned long ip)
+	__releases(lock)
 {
 	struct task_struct *next = NULL;
+	struct mutex_waiter *waiter;
 	DEFINE_WAKE_Q(wake_q);
 	unsigned long owner;
 	unsigned long flags;
 
 	mutex_release(&lock->dep_map, ip);
+	__release(lock);
 
 	/*
 	 * Release the lock before (potentially) taking the spinlock such that
@@ -962,16 +1014,12 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne
 
 	raw_spin_lock_irqsave(&lock->wait_lock, flags);
 	debug_mutex_unlock(lock);
-	if (!list_empty(&lock->wait_list)) {
-		/* get the first entry from the wait-list: */
-		struct mutex_waiter *waiter =
-			list_first_entry(&lock->wait_list,
-					 struct mutex_waiter, list);
-
+	waiter = lock->first_waiter;
+	if (waiter) {
 		next = waiter->task;
 
 		debug_mutex_wake_waiter(lock, waiter);
-		__clear_task_blocked_on(next, lock);
+		set_task_blocked_on_waking(next, lock);
 		wake_q_add(&wake_q, next);
 	}
 
@@ -1061,24 +1109,29 @@ EXPORT_SYMBOL_GPL(mutex_lock_io);
 
 static noinline void __sched
 __mutex_lock_slowpath(struct mutex *lock)
+	__acquires(lock)
 {
 	__mutex_lock(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
+	__acquire(lock);
 }
 
 static noinline int __sched
 __mutex_lock_killable_slowpath(struct mutex *lock)
+	__cond_acquires(0, lock)
 {
 	return __mutex_lock(lock, TASK_KILLABLE, 0, NULL, _RET_IP_);
 }
 
 static noinline int __sched
 __mutex_lock_interruptible_slowpath(struct mutex *lock)
+	__cond_acquires(0, lock)
 {
 	return __mutex_lock(lock, TASK_INTERRUPTIBLE, 0, NULL, _RET_IP_);
 }
 
 static noinline int __sched
 __ww_mutex_lock_slowpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
+	__cond_acquires(0, lock)
 {
 	return __ww_mutex_lock(&lock->base, TASK_UNINTERRUPTIBLE, 0,
 			       _RET_IP_, ctx);
@@ -1087,6 +1140,7 @@ __ww_mutex_lock_slowpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
 static noinline int __sched
 __ww_mutex_lock_interruptible_slowpath(struct ww_mutex *lock,
 					    struct ww_acquire_ctx *ctx)
+	__cond_acquires(0, lock)
 {
 	return __ww_mutex_lock(&lock->base, TASK_INTERRUPTIBLE, 0,
 			       _RET_IP_, ctx);