Messages in this thread Patch in this message | | | Date | Fri, 26 Aug 2016 14:45:28 +0200 | From | Oleg Nesterov <> | Subject | [PATCH 1/2] sched/wait: abort_exclusive_wait() should pass TASK_NORMAL to wake_up() |
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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@redhat.com> --- 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 27d7a0a..329f796 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; \ @@ -976,7 +976,7 @@ 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); -- 2.5.0
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