locking/rwsem: Add ACQUIRE comments (6ffddfb9) · Commits · 戴 / test

kernel/locking/rwsem.c

+13 −5

Original line number	Diff line number	Diff line
		@@ -1004,6 +1004,7 @@ rwsem_down_read_slowpath(struct rw_semaphore *sem, int state)
		atomic_long_add(-RWSEM_READER_BIAS, &sem->count);
		adjustment = 0;
		if (rwsem_optimistic_spin(sem, false)) {
		/* rwsem_optimistic_spin() implies ACQUIRE on success */
		/*
		* Wake up other readers in the wait list if the front
		* waiter is a reader.
		@@ -1018,6 +1019,7 @@ rwsem_down_read_slowpath(struct rw_semaphore *sem, int state)
		}
		return sem;
		} else if (rwsem_reader_phase_trylock(sem, waiter.last_rowner)) {
		/* rwsem_reader_phase_trylock() implies ACQUIRE on success */
		return sem;
		}

		@@ -1071,10 +1073,10 @@ queue:
		wake_up_q(&wake_q);

		/* wait to be given the lock */
		while (true) {
		for (;;) {
		set_current_state(state);
		if (!smp_load_acquire(&waiter.task)) {
		/* Orders against rwsem_mark_wake()'s smp_store_release() */
		/* Matches rwsem_mark_wake()'s smp_store_release(). */
		break;
		}
		if (signal_pending_state(state, current)) {
		@@ -1082,6 +1084,7 @@ queue:
		if (waiter.task)
		goto out_nolock;
		raw_spin_unlock_irq(&sem->wait_lock);
		/* Ordered by sem->wait_lock against rwsem_mark_wake(). */
		break;
		}
		schedule();
		@@ -1091,6 +1094,7 @@ queue:
		__set_current_state(TASK_RUNNING);
		lockevent_inc(rwsem_rlock);
		return sem;

		out_nolock:
		list_del(&waiter.list);
		if (list_empty(&sem->wait_list)) {
		@@ -1131,8 +1135,10 @@ rwsem_down_write_slowpath(struct rw_semaphore *sem, int state)

		/* do optimistic spinning and steal lock if possible */
		if (rwsem_can_spin_on_owner(sem, RWSEM_WR_NONSPINNABLE) &&
		rwsem_optimistic_spin(sem, true))
		rwsem_optimistic_spin(sem, true)) {
		/* rwsem_optimistic_spin() implies ACQUIRE on success */
		return sem;
		}

		/*
		* Disable reader optimistic spinning for this rwsem after
		@@ -1192,9 +1198,11 @@ rwsem_down_write_slowpath(struct rw_semaphore *sem, int state)
		wait:
		/* wait until we successfully acquire the lock */
		set_current_state(state);
		while (true) {
		if (rwsem_try_write_lock(sem, wstate))
		for (;;) {
		if (rwsem_try_write_lock(sem, wstate)) {
		/* rwsem_try_write_lock() implies ACQUIRE on success */
		break;
		}

		raw_spin_unlock_irq(&sem->wait_lock);

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