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-rw-r--r--lib/rwsem.c33
1 files changed, 9 insertions, 24 deletions
diff --git a/lib/rwsem.c b/lib/rwsem.c
index 66f307e90761..c73bd96dc30c 100644
--- a/lib/rwsem.c
+++ b/lib/rwsem.c
@@ -161,16 +161,8 @@ static int try_get_writer_sem(struct rw_semaphore *sem,
try_again_write:
oldcount = rwsem_atomic_update(adjustment, sem) - adjustment;
- if (!(oldcount & RWSEM_ACTIVE_MASK)) {
- /* No active lock: */
- struct task_struct *tsk = waiter->task;
-
- list_del(&waiter->list);
- smp_mb();
- put_task_struct(tsk);
- tsk->state = TASK_RUNNING;
+ if (!(oldcount & RWSEM_ACTIVE_MASK))
return 1;
- }
/* some one grabbed the sem already */
if (rwsem_atomic_update(-adjustment, sem) & RWSEM_ACTIVE_MASK)
return 0;
@@ -220,11 +212,10 @@ struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem)
}
/*
- * wait for the write lock to be granted
+ * wait until we successfully acquire the write lock
*/
struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem)
{
- enum rwsem_waiter_type type = RWSEM_WAITING_FOR_WRITE;
signed long adjustment = -RWSEM_ACTIVE_WRITE_BIAS;
struct rwsem_waiter waiter;
struct task_struct *tsk = current;
@@ -232,8 +223,7 @@ struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem)
/* set up my own style of waitqueue */
waiter.task = tsk;
- waiter.type = type;
- get_task_struct(tsk);
+ waiter.type = RWSEM_WAITING_FOR_WRITE;
raw_spin_lock_irq(&sem->wait_lock);
if (list_empty(&sem->wait_list))
@@ -255,25 +245,20 @@ struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem)
adjustment == -RWSEM_ACTIVE_WRITE_BIAS)
sem = __rwsem_do_wake(sem, RWSEM_WAKE_READ_OWNED);
- raw_spin_unlock_irq(&sem->wait_lock);
-
- /* wait to be given the lock */
+ /* wait until we successfully acquire the lock */
while (true) {
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
- if (!waiter.task)
+
+ if (try_get_writer_sem(sem, &waiter))
break;
- raw_spin_lock_irq(&sem->wait_lock);
- /* Try to get the writer sem, may steal from the head writer: */
- if (type == RWSEM_WAITING_FOR_WRITE)
- if (try_get_writer_sem(sem, &waiter)) {
- raw_spin_unlock_irq(&sem->wait_lock);
- return sem;
- }
raw_spin_unlock_irq(&sem->wait_lock);
schedule();
+ raw_spin_lock_irq(&sem->wait_lock);
}
+ list_del(&waiter.list);
+ raw_spin_unlock_irq(&sem->wait_lock);
tsk->state = TASK_RUNNING;
return sem;

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