Commit a038e253 authored by Paolo 'Blaisorblade' Giarrusso's avatar Paolo 'Blaisorblade' Giarrusso Committed by Jens Axboe

[PATCH] blk_start_queue() must be called with irq disabled - add warning

The queue lock can be taken from interrupts so it must always be taken with
irq disabling primitives.  Some primitives already verify this.
blk_start_queue() is called under this lock, so interrupts must be
disabled.

Also document this requirement clearly in blk_init_queue(), where the queue
spinlock is set.
Signed-off-by: default avatarPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarJens Axboe <axboe@suse.de>
parent bae386f7
...@@ -1663,6 +1663,8 @@ static void blk_unplug_timeout(unsigned long data) ...@@ -1663,6 +1663,8 @@ static void blk_unplug_timeout(unsigned long data)
**/ **/
void blk_start_queue(request_queue_t *q) void blk_start_queue(request_queue_t *q)
{ {
WARN_ON(!irqs_disabled());
clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
/* /*
...@@ -1878,7 +1880,8 @@ EXPORT_SYMBOL(blk_alloc_queue_node); ...@@ -1878,7 +1880,8 @@ EXPORT_SYMBOL(blk_alloc_queue_node);
* get dealt with eventually. * get dealt with eventually.
* *
* The queue spin lock must be held while manipulating the requests on the * The queue spin lock must be held while manipulating the requests on the
* request queue. * request queue; this lock will be taken also from interrupt context, so irq
* disabling is needed for it.
* *
* Function returns a pointer to the initialized request queue, or NULL if * Function returns a pointer to the initialized request queue, or NULL if
* it didn't succeed. * it didn't succeed.
......
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