posix-timers: Annotate lock_timer()

lock_timer() conditionally grabs it_lock in case of returning non-NULL
but unlock_timer() releases it unconditionally. This leads sparse to
complain about the lock context imbalance. Rename and wrap lock_timer
using __cond_lock() macro to make sparse happy.

Signed-off-by: Namhyung Kim <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>

kernel/posix-timers.c

···
 
 static enum hrtimer_restart posix_timer_fn(struct hrtimer *data);
 
-static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags);
+static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags);
+
+#define lock_timer(tid, flags)						   \
+({	struct k_itimer *__timr;					   \
+	__cond_lock(&__timr->it_lock, __timr = __lock_timer(tid, flags));  \
+	__timr;								   \
+})
 
 static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
 {
···
  * the find to the timer lock.  To avoid a dead lock, the timer id MUST
  * be release with out holding the timer lock.
  */
-static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags)
+static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags)
 {
 	struct k_itimer *timr;
 	/*