1 files changed, 17 insertions, 10 deletions

diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index 1c0d11e8ce34..e4ad019e23f5 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -298,23 +298,30 @@ 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 = false;
+        bool ret = true;
 
         if (need_resched())
                 return false;
 
         rcu_read_lock();
         owner = ACCESS_ONCE(sem->owner);
-        if (owner)
-                on_cpu = owner->on_cpu;
-        rcu_read_unlock();
+        if (!owner) {
+                long count = ACCESS_ONCE(sem->count);
+                /*
+                 * If sem->owner is not set, yet we have just recently entered the
+                 * slowpath with the lock being active, then there is a possibility
+                 * reader(s) may have the lock. To be safe, bail spinning in these
+                 * situations.
+                 */
+                if (count & RWSEM_ACTIVE_MASK)
+                        ret = false;
+                goto done;
+        }
 
-        /*
-         * 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;
+        ret = owner->on_cpu;
+done:
+        rcu_read_unlock();
+        return ret;
 }
 
 static inline bool owner_running(struct rw_semaphore *sem,