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Diffstat (limited to 'kernel/locking/rwsem-xadd.c')
-rw-r--r--kernel/locking/rwsem-xadd.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index 3064c50e181e..09b180063ee1 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -180,7 +180,7 @@ static void __rwsem_mark_wake(struct rw_semaphore *sem,
* but it gives the spinners an early indication that the
* readers now have the lock.
*/
- rwsem_set_reader_owned(sem);
+ __rwsem_set_reader_owned(sem, waiter->task);
}
/*
@@ -233,8 +233,19 @@ __rwsem_down_read_failed_common(struct rw_semaphore *sem, int state)
waiter.type = RWSEM_WAITING_FOR_READ;
raw_spin_lock_irq(&sem->wait_lock);
- if (list_empty(&sem->wait_list))
+ if (list_empty(&sem->wait_list)) {
+ /*
+ * In case the wait queue is empty and the lock isn't owned
+ * by a writer, this reader can exit the slowpath and return
+ * immediately as its RWSEM_ACTIVE_READ_BIAS has already
+ * been set in the count.
+ */
+ if (atomic_long_read(&sem->count) >= 0) {
+ raw_spin_unlock_irq(&sem->wait_lock);
+ return sem;
+ }
adjustment += RWSEM_WAITING_BIAS;
+ }
list_add_tail(&waiter.list, &sem->wait_list);
/* we're now waiting on the lock, but no longer actively locking */