use wrapper functions.
epoll should not touch flags in wait_queue_t. This patch introduces a new
function add_wait_queue_head_exclusive_locked(), for the users, who use
wait queue as a LIFO queue.
Signed-off-by: Changli Gao <xiaosuo@xxxxxxxxx>
----
fs/eventpoll.c | 5 ++---
include/linux/wait.h | 15 +++++++++++++--
2 files changed, 15 insertions(+), 5 deletions(-)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index bd056a5..8137f6e 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1140,8 +1140,7 @@ retry:
* ep_poll_callback() when events will become available.
*/
init_waitqueue_entry(&wait, current);
- wait.flags |= WQ_FLAG_EXCLUSIVE;
- __add_wait_queue(&ep->wq, &wait);
+ add_wait_queue_head_exclusive_locked(&ep->wq, &wait);
for (;;) {
/*
@@ -1161,7 +1160,7 @@ retry:
jtimeout = schedule_timeout(jtimeout);
spin_lock_irqsave(&ep->lock, flags);
}
- __remove_wait_queue(&ep->wq, &wait);
+ remove_wait_queue_locked(&ep->wq, &wait);
set_current_state(TASK_RUNNING);
}
diff --git a/include/linux/wait.h b/include/linux/wait.h
index a48e16b..de2566d 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -407,17 +407,28 @@ do { \
* Must be called with the spinlock in the wait_queue_head_t held.
*/
static inline void add_wait_queue_exclusive_locked(wait_queue_head_t *q,
- wait_queue_t * wait)
+ wait_queue_t *wait)
{
wait->flags |= WQ_FLAG_EXCLUSIVE;
__add_wait_queue_tail(q, wait);
}
/*
+ * Must be called with the spinlock in the wait_queue_head_t held, and
+ * q must be for exclusive wait only.
+ */
+static inline void add_wait_queue_head_exclusive_locked(wait_queue_head_t *q,
+ wait_queue_t *wait)
+{
+ wait->flags |= WQ_FLAG_EXCLUSIVE;
+ __add_wait_queue(q, wait);
+}
+
+/*
* Must be called with the spinlock in the wait_queue_head_t held.
*/
static inline void remove_wait_queue_locked(wait_queue_head_t *q,
- wait_queue_t * wait)
+ wait_queue_t *wait)
{
__remove_wait_queue(q, wait);
}
--
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