Move the rwsem_down_read_failed() function down to below the optimistic
spinning section before enabling optimistic spinning for the readers.
There is no change in code.
Signed-off-by: Waiman Long <Waiman.Long@xxxxxx>
---
kernel/locking/rwsem-xadd.c | 96 +++++++++++++++++++++---------------------
1 files changed, 48 insertions(+), 48 deletions(-)
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index 576d4cd..86618ea 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -239,54 +239,6 @@ __rwsem_do_wake(struct rw_semaphore *sem, enum rwsem_wake_type wake_type)
return sem;
}
-/*
- * Wait for the read lock to be granted
- */
-__visible
-struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem)
-{
- long count, adjustment = -RWSEM_ACTIVE_READ_BIAS;
- struct rwsem_waiter waiter;
- struct task_struct *tsk = current;
-
- /* set up my own style of waitqueue */
- waiter.task = tsk;
- waiter.type = RWSEM_WAITING_FOR_READ;
- get_task_struct(tsk);
-
- raw_spin_lock_irq(&sem->wait_lock);
- if (list_empty(&sem->wait_list))
- adjustment += RWSEM_WAITING_BIAS;
- list_add_tail(&waiter.list, &sem->wait_list);
-
- /* 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).
- *
- * If there are no writers and we are first in the queue,
- * wake our own waiter to join the existing active readers !
- */
- if (count == RWSEM_WAITING_BIAS ||
- (count > RWSEM_WAITING_BIAS &&
- adjustment != -RWSEM_ACTIVE_READ_BIAS))
- sem = __rwsem_do_wake(sem, RWSEM_WAKE_ANY);
-
- raw_spin_unlock_irq(&sem->wait_lock);
-
- /* wait to be given the lock */
- while (true) {
- set_task_state(tsk, TASK_UNINTERRUPTIBLE);
- if (!waiter.task)
- break;
- schedule();
- }
-
- tsk->state = TASK_RUNNING;
-
- return sem;
-}
-
static inline bool rwsem_try_write_lock(long count, struct rw_semaphore *sem)
{
if (!(count & RWSEM_ACTIVE_MASK)) {
@@ -458,6 +410,54 @@ static bool rwsem_optimistic_spin(struct rw_semaphore *sem)
#endif
/*
+ * Wait for the read lock to be granted
+ */
+__visible
+struct rw_semaphore __sched * rwsem_down_read_failed(struct rw_semaphore *sem)
+{
+ long count, adjustment = -RWSEM_ACTIVE_READ_BIAS;
+ struct rwsem_waiter waiter;
+ struct task_struct *tsk = current;
+
+ /* set up my own style of waitqueue */
+ waiter.task = tsk;
+ waiter.type = RWSEM_WAITING_FOR_READ;
+ get_task_struct(tsk);
+
+ raw_spin_lock_irq(&sem->wait_lock);
+ if (list_empty(&sem->wait_list))
+ adjustment += RWSEM_WAITING_BIAS;
+ list_add_tail(&waiter.list, &sem->wait_list);
+
+ /* 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).
+ *
+ * If there are no writers and we are first in the queue,
+ * wake our own waiter to join the existing active readers !
+ */
+ if (count == RWSEM_WAITING_BIAS ||
+ (count > RWSEM_WAITING_BIAS &&
+ adjustment != -RWSEM_ACTIVE_READ_BIAS))
+ sem = __rwsem_do_wake(sem, RWSEM_WAKE_ANY);
+
+ raw_spin_unlock_irq(&sem->wait_lock);
+
+ /* wait to be given the lock */
+ while (true) {
+ set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+ if (!waiter.task)
+ break;
+ schedule();
+ }
+
+ tsk->state = TASK_RUNNING;
+
+ return sem;
+}
+
+/*
* Wait until we successfully acquire the write lock
*/
__visible
--
1.7.1
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