Commit 8e9c3ec4 authored by Jens Axboe's avatar Jens Axboe Committed by Linus Torvalds

[PATCH] unplugging fix

Fix queue plug locking.
parent ea8e69e8
...@@ -821,7 +821,7 @@ static inline void __generic_unplug_device(request_queue_t *q) ...@@ -821,7 +821,7 @@ static inline void __generic_unplug_device(request_queue_t *q)
/* /*
* not plugged * not plugged
*/ */
if (!__test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
return; return;
if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)) if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags))
...@@ -893,6 +893,20 @@ void blk_start_queue(request_queue_t *q) ...@@ -893,6 +893,20 @@ void blk_start_queue(request_queue_t *q)
**/ **/
void blk_stop_queue(request_queue_t *q) void blk_stop_queue(request_queue_t *q)
{ {
unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags);
/*
* remove from the plugged list, queue must not be called.
*/
if (test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) {
spin_lock(&blk_plug_lock);
list_del(&q->plug_list);
spin_unlock(&blk_plug_lock);
}
spin_unlock_irqrestore(q->queue_lock, flags);
set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
} }
...@@ -904,45 +918,36 @@ void blk_stop_queue(request_queue_t *q) ...@@ -904,45 +918,36 @@ void blk_stop_queue(request_queue_t *q)
* are currently stopped are ignored. This is equivalent to the older * are currently stopped are ignored. This is equivalent to the older
* tq_disk task queue run. * tq_disk task queue run.
**/ **/
#define blk_plug_entry(entry) list_entry((entry), request_queue_t, plug_list)
void blk_run_queues(void) void blk_run_queues(void)
{ {
struct list_head *n, *tmp, local_plug_list; struct list_head local_plug_list;
unsigned long flags;
INIT_LIST_HEAD(&local_plug_list); INIT_LIST_HEAD(&local_plug_list);
spin_lock_irq(&blk_plug_lock);
/* /*
* this will happen fairly often * this will happen fairly often
*/ */
spin_lock_irqsave(&blk_plug_lock, flags);
if (list_empty(&blk_plug_list)) { if (list_empty(&blk_plug_list)) {
spin_unlock_irqrestore(&blk_plug_lock, flags); spin_unlock_irq(&blk_plug_lock);
return; return;
} }
list_splice(&blk_plug_list, &local_plug_list); list_splice(&blk_plug_list, &local_plug_list);
INIT_LIST_HEAD(&blk_plug_list); INIT_LIST_HEAD(&blk_plug_list);
spin_unlock_irqrestore(&blk_plug_lock, flags); spin_unlock_irq(&blk_plug_lock);
/* while (!list_empty(&local_plug_list)) {
* local_plug_list is now a private copy we can traverse lockless request_queue_t *q = blk_plug_entry(local_plug_list.next);
*/
list_for_each_safe(n, tmp, &local_plug_list) {
request_queue_t *q = list_entry(n, request_queue_t, plug_list);
if (!test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)) { BUG_ON(test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags));
list_del(&q->plug_list);
generic_unplug_device(q);
}
}
/* spin_lock_irq(q->queue_lock);
* add any remaining queue back to plug list list_del(&q->plug_list);
*/ __generic_unplug_device(q);
if (!list_empty(&local_plug_list)) { spin_unlock_irq(q->queue_lock);
spin_lock_irqsave(&blk_plug_lock, flags);
list_splice(&local_plug_list, &blk_plug_list);
spin_unlock_irqrestore(&blk_plug_lock, flags);
} }
} }
......
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