locking, rwsem: Annotate inner lock as raw

There is no reason to allow the lock protecting rwsems (the
ownerless variant) to be preemptible on -rt. Convert it to raw.

In mainline this change documents the low level nature of
the lock - otherwise there's no functional difference. Lockdep
and Sparse checking will work as usual.

Signed-off-by: Thomas Gleixner <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>

include/linux/rwsem-spinlock.h

···
  */
 struct rw_semaphore {
 	__s32			activity;
-	spinlock_t		wait_lock;
+	raw_spinlock_t		wait_lock;
 	struct list_head	wait_list;
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 	struct lockdep_map dep_map;

include/linux/rwsem.h

···
 /* All arch specific implementations share the same struct */
 struct rw_semaphore {
 	long			count;
-	spinlock_t		wait_lock;
+	raw_spinlock_t		wait_lock;
 	struct list_head	wait_list;
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 	struct lockdep_map	dep_map;
···
 # define __RWSEM_DEP_MAP_INIT(lockname)
 #endif
 
-#define __RWSEM_INITIALIZER(name) \
-	{ RWSEM_UNLOCKED_VALUE, __SPIN_LOCK_UNLOCKED(name.wait_lock),	\
-	  LIST_HEAD_INIT((name).wait_list) __RWSEM_DEP_MAP_INIT(name) }
+#define __RWSEM_INITIALIZER(name)			\
+	{ RWSEM_UNLOCKED_VALUE,				\
+	  __RAW_SPIN_LOCK_UNLOCKED(name.wait_lock),	\
+	  LIST_HEAD_INIT((name).wait_list)		\
+	  __RWSEM_DEP_MAP_INIT(name) }
 
 #define DECLARE_RWSEM(name) \
 	struct rw_semaphore name = __RWSEM_INITIALIZER(name)

lib/rwsem-spinlock.c

···
 	int ret = 1;
 	unsigned long flags;
 
-	if (spin_trylock_irqsave(&sem->wait_lock, flags)) {
+	if (raw_spin_trylock_irqsave(&sem->wait_lock, flags)) {
 		ret = (sem->activity != 0);
-		spin_unlock_irqrestore(&sem->wait_lock, flags);
+		raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
 	}
 	return ret;
 }
···
 	lockdep_init_map(&sem->dep_map, name, key, 0);
 #endif
 	sem->activity = 0;
-	spin_lock_init(&sem->wait_lock);
+	raw_spin_lock_init(&sem->wait_lock);
 	INIT_LIST_HEAD(&sem->wait_list);
 }
 EXPORT_SYMBOL(__init_rwsem);
···
 	struct task_struct *tsk;
 	unsigned long flags;
 
-	spin_lock_irqsave(&sem->wait_lock, flags);
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
 
 	if (sem->activity >= 0 && list_empty(&sem->wait_list)) {
 		/* granted */
 		sem->activity++;
-		spin_unlock_irqrestore(&sem->wait_lock, flags);
+		raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
 		goto out;
 	}
 
···
 	list_add_tail(&waiter.list, &sem->wait_list);
 
 	/* we don't need to touch the semaphore struct anymore */
-	spin_unlock_irqrestore(&sem->wait_lock, flags);
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
 
 	/* wait to be given the lock */
 	for (;;) {
···
 	int ret = 0;
 
 
-	spin_lock_irqsave(&sem->wait_lock, flags);
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
 
 	if (sem->activity >= 0 && list_empty(&sem->wait_list)) {
 		/* granted */
···
 		ret = 1;
 	}
 
-	spin_unlock_irqrestore(&sem->wait_lock, flags);
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
 
 	return ret;
 }
···
 	struct task_struct *tsk;
 	unsigned long flags;
 
-	spin_lock_irqsave(&sem->wait_lock, flags);
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
 
 	if (sem->activity == 0 && list_empty(&sem->wait_list)) {
 		/* granted */
 		sem->activity = -1;
-		spin_unlock_irqrestore(&sem->wait_lock, flags);
+		raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
 		goto out;
 	}
 
···
 	list_add_tail(&waiter.list, &sem->wait_list);
 
 	/* we don't need to touch the semaphore struct anymore */
-	spin_unlock_irqrestore(&sem->wait_lock, flags);
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
 
 	/* wait to be given the lock */
 	for (;;) {
···
 	unsigned long flags;
 	int ret = 0;
 
-	spin_lock_irqsave(&sem->wait_lock, flags);
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
 
 	if (sem->activity == 0 && list_empty(&sem->wait_list)) {
 		/* granted */
···
 		ret = 1;
 	}
 
-	spin_unlock_irqrestore(&sem->wait_lock, flags);
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
 
 	return ret;
 }
···
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&sem->wait_lock, flags);
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
 
 	if (--sem->activity == 0 && !list_empty(&sem->wait_list))
 		sem = __rwsem_wake_one_writer(sem);
 
-	spin_unlock_irqrestore(&sem->wait_lock, flags);
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
 }
 
 /*
···
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&sem->wait_lock, flags);
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
 
 	sem->activity = 0;
 	if (!list_empty(&sem->wait_list))
 		sem = __rwsem_do_wake(sem, 1);
 
-	spin_unlock_irqrestore(&sem->wait_lock, flags);
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
 }
 
 /*
···
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&sem->wait_lock, flags);
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
 
 	sem->activity = 1;
 	if (!list_empty(&sem->wait_list))
 		sem = __rwsem_do_wake(sem, 0);
 
-	spin_unlock_irqrestore(&sem->wait_lock, flags);
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
 }
 

lib/rwsem.c

···
 	lockdep_init_map(&sem->dep_map, name, key, 0);
 #endif
 	sem->count = RWSEM_UNLOCKED_VALUE;
-	spin_lock_init(&sem->wait_lock);
+	raw_spin_lock_init(&sem->wait_lock);
 	INIT_LIST_HEAD(&sem->wait_list);
 }
 
···
 	set_task_state(tsk, TASK_UNINTERRUPTIBLE);
 
 	/* set up my own style of waitqueue */
-	spin_lock_irq(&sem->wait_lock);
+	raw_spin_lock_irq(&sem->wait_lock);
 	waiter.task = tsk;
 	waiter.flags = flags;
 	get_task_struct(tsk);
···
 		 adjustment == -RWSEM_ACTIVE_WRITE_BIAS)
 		sem = __rwsem_do_wake(sem, RWSEM_WAKE_READ_OWNED);
 
-	spin_unlock_irq(&sem->wait_lock);
+	raw_spin_unlock_irq(&sem->wait_lock);
 
 	/* wait to be given the lock */
 	for (;;) {
···
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&sem->wait_lock, flags);
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
 
 	/* do nothing if list empty */
 	if (!list_empty(&sem->wait_list))
 		sem = __rwsem_do_wake(sem, RWSEM_WAKE_ANY);
 
-	spin_unlock_irqrestore(&sem->wait_lock, flags);
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
 
 	return sem;
 }
···
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&sem->wait_lock, flags);
+	raw_spin_lock_irqsave(&sem->wait_lock, flags);
 
 	/* do nothing if list empty */
 	if (!list_empty(&sem->wait_list))
 		sem = __rwsem_do_wake(sem, RWSEM_WAKE_READ_OWNED);
 
-	spin_unlock_irqrestore(&sem->wait_lock, flags);
+	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
 
 	return sem;
 }