locking/rt: Add sparse annotation PREEMPT_RT's sleeping locks.

The sleeping locks on PREEMPT_RT (rt_spin_lock() and friends) lack
sparse annotation. Therefore a missing spin_unlock() won't be spotted by
sparse in a PREEMPT_RT build while it is noticed on a !PREEMPT_RT build.

Add the __acquires/__releases macros to the lock/ unlock functions. The
trylock functions already use the __cond_lock() wrapper.

Signed-off-by: Sebastian Andrzej Siewior <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Link: https://lore.kernel.org/all/[e-mail]

include/linux/rwlock_rt.h

···
 	__rt_rwlock_init(rwl, #rwl, &__key);		\
 } while (0)
 
-extern void rt_read_lock(rwlock_t *rwlock);
+extern void rt_read_lock(rwlock_t *rwlock)	__acquires(rwlock);
 extern int rt_read_trylock(rwlock_t *rwlock);
-extern void rt_read_unlock(rwlock_t *rwlock);
-extern void rt_write_lock(rwlock_t *rwlock);
-extern void rt_write_lock_nested(rwlock_t *rwlock, int subclass);
+extern void rt_read_unlock(rwlock_t *rwlock)	__releases(rwlock);
+extern void rt_write_lock(rwlock_t *rwlock)	__acquires(rwlock);
+extern void rt_write_lock_nested(rwlock_t *rwlock, int subclass)	__acquires(rwlock);
 extern int rt_write_trylock(rwlock_t *rwlock);
-extern void rt_write_unlock(rwlock_t *rwlock);
+extern void rt_write_unlock(rwlock_t *rwlock)	__releases(rwlock);
 
 static __always_inline void read_lock(rwlock_t *rwlock)
 {

include/linux/spinlock_rt.h

···
 	__rt_spin_lock_init(slock, #slock, &__key, true);	\
 } while (0)
 
-extern void rt_spin_lock(spinlock_t *lock);
-extern void rt_spin_lock_nested(spinlock_t *lock, int subclass);
-extern void rt_spin_lock_nest_lock(spinlock_t *lock, struct lockdep_map *nest_lock);
-extern void rt_spin_unlock(spinlock_t *lock);
+extern void rt_spin_lock(spinlock_t *lock) __acquires(lock);
+extern void rt_spin_lock_nested(spinlock_t *lock, int subclass)	__acquires(lock);
+extern void rt_spin_lock_nest_lock(spinlock_t *lock, struct lockdep_map *nest_lock) __acquires(lock);
+extern void rt_spin_unlock(spinlock_t *lock)	__releases(lock);
 extern void rt_spin_lock_unlock(spinlock_t *lock);
 extern int rt_spin_trylock_bh(spinlock_t *lock);
 extern int rt_spin_trylock(spinlock_t *lock);