use wrapper functions
epoll should not touch flags in wait_queue_t. This patch introduces a new
function __add_wait_queue_excl(), for the users, who use wait queue as a
LIFO queue.
__add_wait_queue_tail_excl() is introduced too instead of
add_wait_queue_exclusive_locked(). remove_wait_queue_locked() is removed, as
it is a duplicate of __remove_wait_queue(), disliked by users, and with less
users.
Signed-off-by: Changli Gao <xiaosuo@xxxxxxxxx>
----
fs/eventpoll.c | 3 +--
include/linux/wait.h | 35 +++++++++++++++--------------------
kernel/cgroup.c | 2 +-
kernel/sched.c | 3 +--
4 files changed, 18 insertions(+), 25 deletions(-)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index bd056a5..a6ba470 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_excl(&ep->wq, &wait);
for (;;) {
/*
diff --git a/include/linux/wait.h b/include/linux/wait.h
index a48e16b..4db4147 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -127,12 +127,26 @@ static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
/*
* Used for wake-one threads:
*/
+static inline void __add_wait_queue_excl(wait_queue_head_t *q,
+ wait_queue_t *wait)
+{
+ wait->flags |= WQ_FLAG_EXCLUSIVE;
+ __add_wait_queue(q, wait);
+}
+
static inline void __add_wait_queue_tail(wait_queue_head_t *head,
- wait_queue_t *new)
+ wait_queue_t *new)
{
list_add_tail(&new->task_list, &head->task_list);
}
+static inline void __add_wait_queue_tail_excl(wait_queue_head_t *q,
+ wait_queue_t *wait)
+{
+ wait->flags |= WQ_FLAG_EXCLUSIVE;
+ __add_wait_queue_tail(q, wait);
+}
+
static inline void __remove_wait_queue(wait_queue_head_t *head,
wait_queue_t *old)
{
@@ -404,25 +418,6 @@ 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->flags |= WQ_FLAG_EXCLUSIVE;
- __add_wait_queue_tail(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)
-{
- __remove_wait_queue(q, wait);
-}
-
-/*
* These are the old interfaces to sleep waiting for an event.
* They are racy. DO NOT use them, use the wait_event* interfaces above.
* We plan to remove these interfaces.
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e2769e1..4a07d05 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3010,7 +3010,7 @@ static int cgroup_event_wake(wait_queue_t *wait, unsigned mode,
unsigned long flags = (unsigned long)key;
if (flags & POLLHUP) {
- remove_wait_queue_locked(event->wqh, &event->wait);
+ __remove_wait_queue(event->wqh, &event->wait);
spin_lock(&cgrp->event_list_lock);
list_del(&event->list);
spin_unlock(&cgrp->event_list_lock);
diff --git a/kernel/sched.c b/kernel/sched.c
index 6af210a..c5c998d 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4039,8 +4039,7 @@ do_wait_for_common(struct completion *x, long timeout, int state)
if (!x->done) {
DECLARE_WAITQUEUE(wait, current);
- wait.flags |= WQ_FLAG_EXCLUSIVE;
- __add_wait_queue_tail(&x->wait, &wait);
+ __add_wait_queue_tail_excl(&x->wait, &wait);
do {
if (signal_pending_state(state, current)) {
timeout = -ERESTARTSYS;
--
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