Merge branches 'samsung/cleanup' and 'samsung/s5p-cleanup-v2', tag 'v3.16-rc6' into...

[cascardo/linux.git] / kernel / locking / rwsem-xadd.c

diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index dacc321..a2391ac 100644 (file)
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -82,9 +82,9 @@ void __init_rwsem(struct rw_semaphore *sem, const char *name,
        sem->count = RWSEM_UNLOCKED_VALUE;
        raw_spin_lock_init(&sem->wait_lock);
        INIT_LIST_HEAD(&sem->wait_list);
-#ifdef CONFIG_SMP
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
        sem->owner = NULL;
-       sem->osq = NULL;
+       osq_lock_init(&sem->osq);
 #endif
 }
 
@@ -262,7 +262,7 @@ static inline bool rwsem_try_write_lock(long count, struct rw_semaphore *sem)
        return false;
 }
 
-#ifdef CONFIG_SMP
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
 /*
  * Try to acquire write lock before the writer has been put on wait queue.
  */
@@ -285,10 +285,10 @@ static inline bool rwsem_try_write_lock_unqueued(struct rw_semaphore *sem)
 static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem)
 {
        struct task_struct *owner;
-       bool on_cpu = true;
+       bool on_cpu = false;
 
        if (need_resched())
-               return 0;
+               return false;
 
        rcu_read_lock();
        owner = ACCESS_ONCE(sem->owner);
@@ -297,9 +297,9 @@ static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem)
        rcu_read_unlock();
 
        /*
-        * If sem->owner is not set, the rwsem owner may have
-        * just acquired it and not set the owner yet or the rwsem
-        * has been released.
+        * If sem->owner is not set, yet we have just recently entered the
+        * slowpath, then there is a possibility reader(s) may have the lock.
+        * To be safe, avoid spinning in these situations.
         */
        return on_cpu;
 }