[2/2] mutex: Apply adaptive spinning on mutex_trylock()

Commit Message

Tejun Heo March 24, 2011, 9:41 a.m. UTC

None

Patch

Index: work/kernel/mutex.c
===================================================================
--- work.orig/kernel/mutex.c
+++ work/kernel/mutex.c
@@ -443,6 +443,15 @@  static inline int __mutex_trylock_slowpa
 	unsigned long flags;
 	int prev;
 
+	preempt_disable();
+
+	if (mutex_spin(lock)) {
+		mutex_set_owner(lock);
+		mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
+		preempt_enable();
+		return 1;
+	}
+
 	spin_lock_mutex(&lock->wait_lock, flags);
 
 	prev = atomic_xchg(&lock->count, -1);
@@ -456,6 +465,7 @@  static inline int __mutex_trylock_slowpa
 		atomic_set(&lock->count, 0);
 
 	spin_unlock_mutex(&lock->wait_lock, flags);
+	preempt_enable();
 
 	return prev == 1;
 }