sched, wait: Use wrapper functions

epoll should not touch flags in wait_queue_t. This patch introduces a new
function __add_wait_queue_exclusive(), for the users, who use wait queue as a
LIFO queue.

__add_wait_queue_tail_exclusive() 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@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: <containers@lists.linux-foundation.org>
LKML-Reference: <1273214006-2979-1-git-send-email-xiaosuo@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index bd056a5b4efc59ceccb8b121100d40e2bb16cf3f..3817149919cb81fa298686f183f67e0c86fe1c50 100644 (file)
--- 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_exclusive(&ep->wq, &wait);
 
                for (;;) {
                        /*

diff --git a/include/linux/wait.h b/include/linux/wait.h
index a48e16b77d5e2d94c1bb1bfb6b5efa56a82bd7af..76d96d035ea03920ac919a13e2b255e93cc77f35 100644 (file)
--- 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_exclusive(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_exclusive(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)
 {
@@ -403,25 +417,6 @@ do {                                                                       \
        __ret;                                                          \
 })
 
-/*
- * 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.

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e2769e13980c49b2546d0bb2c6cef1e0065f6ca7..4a07d057a265f644ad73a56a7e02cac1def8cdce 100644 (file)
--- 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 39aa9c7e22c05492e2a66d1379fef4c1b8f2494d..b531d7934083b3216e50d4e4f6536ef7f08285ed 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3983,8 +3983,7 @@ 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_exclusive(&x->wait, &wait);
                do {
                        if (signal_pending_state(state, current)) {
                                timeout = -ERESTARTSYS;