locking/semaphore: Add might_sleep() to down_*() family

Semaphore is sleeping lock. Add might_sleep() to down*() family
(with exception of down_trylock()) to detect atomic context sleep.

Signed-off-by: Xiaoming Ni <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Will Deacon <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

kernel/locking/semaphore.c

@@ -54,6 +54,7 @@ void down(struct semaphore *sem)
 {
 	unsigned long flags;
 
+	might_sleep();
 	raw_spin_lock_irqsave(&sem->lock, flags);
 	if (likely(sem->count > 0))
 		sem->count--;
@@ -77,6 +78,7 @@ int down_interruptible(struct semaphore *sem)
 	unsigned long flags;
 	int result = 0;
 
+	might_sleep();
 	raw_spin_lock_irqsave(&sem->lock, flags);
 	if (likely(sem->count > 0))
 		sem->count--;
@@ -103,6 +105,7 @@ int down_killable(struct semaphore *sem)
 	unsigned long flags;
 	int result = 0;
 
+	might_sleep();
 	raw_spin_lock_irqsave(&sem->lock, flags);
 	if (likely(sem->count > 0))
 		sem->count--;
@@ -157,6 +160,7 @@ int down_timeout(struct semaphore *sem, long timeout)
 	unsigned long flags;
 	int result = 0;
 
+	might_sleep();
 	raw_spin_lock_irqsave(&sem->lock, flags);
 	if (likely(sem->count > 0))
 		sem->count--;