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>

1 files changed, 19 insertions, 17 deletions

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index ed88021953df..1e8fdabb19de 100644
--- 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;