Commit-ID: 38a3e1fc1dac480f3672ab22fc97e1f995c80ed7
Gitweb: http://git.kernel.org/tip/38a3e1fc1dac480f3672ab22fc97e1f995c80ed7
Author: Oleg Nesterov <oleg@xxxxxxxxxx>
AuthorDate: Tue, 6 Sep 2016 16:00:47 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 30 Sep 2016 10:53:19 +0200
sched/wait: Fix abort_exclusive_wait(), it should pass TASK_NORMAL to wake_up()
Otherwise this logic only works if mode is "compatible" with another
exclusive waiter.
If some wq has both TASK_INTERRUPTIBLE and TASK_UNINTERRUPTIBLE waiters,
abort_exclusive_wait() won't wait an uninterruptible waiter.
The main user is __wait_on_bit_lock() and currently it is fine but only
because TASK_KILLABLE includes TASK_UNINTERRUPTIBLE and we do not have
lock_page_interruptible() yet.
Just use TASK_NORMAL and remove the "mode" arg from abort_exclusive_wait().
Yes, this means that (say) wake_up_interruptible() can wake up the non-
interruptible waiter(s), but I think this is fine. And in fact I think
that abort_exclusive_wait() must die, see the next change.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Bart Van Assche <bvanassche@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Neil Brown <neilb@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20160906140047.GA6157@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/wait.h | 6 +++---
kernel/sched/wait.c | 8 +++-----
2 files changed, 6 insertions(+), 8 deletions(-)
diff --git a/include/linux/wait.h b/include/linux/wait.h
index c3ff74d..e4cfd1e 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -281,8 +281,8 @@ wait_queue_head_t *bit_waitqueue(void *, int);
if (___wait_is_interruptible(state) && __int) { \
__ret = __int; \
if (exclusive) { \
- abort_exclusive_wait(&wq, &__wait, \
- state, NULL); \
+ abort_exclusive_wait(&wq, &__wait, \
+ NULL); \
goto __out; \
} \
break; \
@@ -989,7 +989,7 @@ void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state);
void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
-void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, unsigned int mode, void *key);
+void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, void *key);
long wait_woken(wait_queue_t *wait, unsigned mode, long timeout);
int woken_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index f15d6b6..2bbba01 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -259,7 +259,6 @@ EXPORT_SYMBOL(finish_wait);
* abort_exclusive_wait - abort exclusive waiting in a queue
* @q: waitqueue waited on
* @wait: wait descriptor
- * @mode: runstate of the waiter to be woken
* @key: key to identify a wait bit queue or %NULL
*
* Sets current thread back to running state and removes
@@ -273,8 +272,7 @@ EXPORT_SYMBOL(finish_wait);
* aborts and is woken up concurrently and no one wakes up
* the next waiter.
*/
-void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
- unsigned int mode, void *key)
+void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, void *key)
{
unsigned long flags;
@@ -283,7 +281,7 @@ void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
if (!list_empty(&wait->task_list))
list_del_init(&wait->task_list);
else if (waitqueue_active(q))
- __wake_up_locked_key(q, mode, key);
+ __wake_up_locked_key(q, TASK_NORMAL, key);
spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(abort_exclusive_wait);
@@ -434,7 +432,7 @@ __wait_on_bit_lock(wait_queue_head_t *wq, struct wait_bit_queue *q,
ret = action(&q->key, mode);
if (!ret)
continue;
- abort_exclusive_wait(wq, &q->wait, mode, &q->key);
+ abort_exclusive_wait(wq, &q->wait, &q->key);
return ret;
} while (test_and_set_bit(q->key.bit_nr, q->key.flags));
finish_wait(wq, &q->wait);
--
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