1 files changed, 8 insertions, 21 deletions

diff --git a/lib/rwsem.c b/lib/rwsem.c
index c73bd96dc30c..2360bf204098 100644
--- a/lib/rwsem.c
+++ b/lib/rwsem.c
@@ -143,20 +143,12 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wake_type)
 }
 
 /* Try to get write sem, caller holds sem->wait_lock: */
-static int try_get_writer_sem(struct rw_semaphore *sem,
-                                        struct rwsem_waiter *waiter)
+static int try_get_writer_sem(struct rw_semaphore *sem)
 {
-        struct rwsem_waiter *fwaiter;
         long oldcount, adjustment;
 
-        /* only steal when first waiter is writing */
-        fwaiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);
-        if (fwaiter->type != RWSEM_WAITING_FOR_WRITE)
-                return 0;
-
         adjustment = RWSEM_ACTIVE_WRITE_BIAS;
-        /* Only one waiter in the queue: */
-        if (fwaiter == waiter && waiter->list.next == &sem->wait_list)
+        if (list_is_singular(&sem->wait_list))
                 adjustment -= RWSEM_WAITING_BIAS;
 
 try_again_write:
@@ -233,23 +225,18 @@ struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem)
         /* we're now waiting on the lock, but no longer actively locking */
         count = rwsem_atomic_update(adjustment, sem);
 
-        /* If there are no active locks, wake the front queued process(es) up.
-         *
-         * Alternatively, if we're called from a failed down_write(), there
-         * were already threads queued before us and there are no active
-         * writers, the lock must be read owned; so we try to wake any read
-         * locks that were queued ahead of us. */
-        if (count == RWSEM_WAITING_BIAS)
-                sem = __rwsem_do_wake(sem, RWSEM_WAKE_NO_ACTIVE);
-        else if (count > RWSEM_WAITING_BIAS &&
-                 adjustment == -RWSEM_ACTIVE_WRITE_BIAS)
+        /* If there were already threads queued before us and there are no
+         * active writers, the lock must be read owned; so we try to wake
+         * any read locks that were queued ahead of us. */
+        if (count > RWSEM_WAITING_BIAS &&
+            adjustment == -RWSEM_ACTIVE_WRITE_BIAS)
                 sem = __rwsem_do_wake(sem, RWSEM_WAKE_READ_OWNED);
 
         /* wait until we successfully acquire the lock */
         while (true) {
                 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
 
-                if (try_get_writer_sem(sem, &waiter))
+                if (try_get_writer_sem(sem))
                         break;
 
                 raw_spin_unlock_irq(&sem->wait_lock);