rtmutex: Simplify remove_waiter()

Exit right away, when the removed waiter was not the top priority
waiter on the lock. Get rid of the extra indent level.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index ed88021953df8bbc48753b3d10f980e6f8b7c5db..1e8fdabb19dedb894dc454fe1c2806f917a737b9 100644 (file)
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -917,9 +917,9 @@ static void wakeup_next_waiter(struct rt_mutex *lock)
 static void remove_waiter(struct rt_mutex *lock,
                          struct rt_mutex_waiter *waiter)
 {
-       int first = (waiter == rt_mutex_top_waiter(lock));
+       bool is_top_waiter = (waiter == rt_mutex_top_waiter(lock));
        struct task_struct *owner = rt_mutex_owner(lock);
-       struct rt_mutex *next_lock = NULL;
+       struct rt_mutex *next_lock;
        unsigned long flags;
 
        raw_spin_lock_irqsave(&current->pi_lock, flags);
@@ -927,29 +927,31 @@ static void remove_waiter(struct rt_mutex *lock,
        current->pi_blocked_on = NULL;
        raw_spin_unlock_irqrestore(&current->pi_lock, flags);
 
-       if (!owner)
+       /*
+        * Only update priority if the waiter was the highest priority
+        * waiter of the lock and there is an owner to update.
+        */
+       if (!owner || !is_top_waiter)
                return;
 
-       if (first) {
-
-               raw_spin_lock_irqsave(&owner->pi_lock, flags);
+       raw_spin_lock_irqsave(&owner->pi_lock, flags);
 
-               rt_mutex_dequeue_pi(owner, waiter);
+       rt_mutex_dequeue_pi(owner, waiter);
 
-               if (rt_mutex_has_waiters(lock)) {
-                       struct rt_mutex_waiter *next;
+       if (rt_mutex_has_waiters(lock))
+               rt_mutex_enqueue_pi(owner, rt_mutex_top_waiter(lock));
 
-                       next = rt_mutex_top_waiter(lock);
-                       rt_mutex_enqueue_pi(owner, next);
-               }
-               __rt_mutex_adjust_prio(owner);
+       __rt_mutex_adjust_prio(owner);
 
-               /* Store the lock on which owner is blocked or NULL */
-               next_lock = task_blocked_on_lock(owner);
+       /* Store the lock on which owner is blocked or NULL */
+       next_lock = task_blocked_on_lock(owner);
 
-               raw_spin_unlock_irqrestore(&owner->pi_lock, flags);
-       }
+       raw_spin_unlock_irqrestore(&owner->pi_lock, flags);
 
+       /*
+        * Don't walk the chain, if the owner task is not blocked
+        * itself.
+        */
        if (!next_lock)
                return;