From: Paolo 'Blaisorblade' Giarrusso 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. Cc: Jens Axboe Signed-off-by: Paolo 'Blaisorblade' Giarrusso Signed-off-by: Andrew Morton --- block/ll_rw_blk.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletion(-) diff -puN block/ll_rw_blk.c~blk_start_queue-must-be-called-with-irq-disabled-add-warning block/ll_rw_blk.c --- devel/block/ll_rw_blk.c~blk_start_queue-must-be-called-with-irq-disabled-add-warning 2006-05-11 15:17:48.000000000 -0700 +++ devel-akpm/block/ll_rw_blk.c 2006-05-11 15:17:48.000000000 -0700 @@ -1663,6 +1663,8 @@ static void blk_unplug_timeout(unsigned **/ void blk_start_queue(request_queue_t *q) { + WARN_ON(!irqs_disabled()); + clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); /* @@ -1878,7 +1880,8 @@ EXPORT_SYMBOL(blk_alloc_queue_node); * get dealt with eventually. * * 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 * it didn't succeed. _