From: Tejun Heo <[email protected]> commit 8ba61435d73f2274e12d4d823fde06735e8f6a54 upstream.
blk_insert_cloned_request(), blk_execute_rq_nowait() and blk_flush_plug_list() either didn't check whether the queue was dead or did it without holding queue_lock. Update them so that dead state is checked while holding queue_lock. AFAICS, this plugs all holes (requeue doesn't matter as the request is transitioning atomically from in_flight to queued). Signed-off-by: Tejun Heo <[email protected]> Signed-off-by: Jens Axboe <[email protected]> [bwh: Backported to 2.6.32: - Drop inapplicable changes to queue_unplugged() and blk_flush_plug_list() - We don't have blk_queue_dead() so open-code it - Adjust context] Signed-off-by: Ben Hutchings <[email protected]> --- This is not as complete as the upstream version. I couldn't work out where the 'dead' check belongs in the unplugging functions. It does fix the locking around the 'dead' check in blk_execute_rq_nowait() which was added by "fix crash in scsi_dispatch_cmd()" in 2.6.32.61. Ben. block/blk-core.c | 4 ++++ block/blk-exec.c | 6 ++++-- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 4058f46..fc40ab9 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1651,6 +1651,10 @@ int blk_insert_cloned_request(struct request_queue *q, struct request *rq) #endif spin_lock_irqsave(q->queue_lock, flags); + if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { + spin_unlock_irqrestore(q->queue_lock, flags); + return -ENODEV; + } /* * Submitting request must be dequeued before calling this function diff --git a/block/blk-exec.c b/block/blk-exec.c index 85bd7b4..ae0f2c7 100644 --- a/block/blk-exec.c +++ b/block/blk-exec.c @@ -50,7 +50,11 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk, { int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; + WARN_ON(irqs_disabled()); + spin_lock_irq(q->queue_lock); + if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { + spin_unlock_irq(q->queue_lock); rq->errors = -ENXIO; if (rq->end_io) rq->end_io(rq, rq->errors); @@ -59,8 +63,6 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk, rq->rq_disk = bd_disk; rq->end_io = done; - WARN_ON(irqs_disabled()); - spin_lock_irq(q->queue_lock); __elv_add_request(q, rq, where, 1); __generic_unplug_device(q); /* the queue is stopped so it won't be plugged+unplugged */ -- Ben Hutchings Experience is directly proportional to the value of equipment destroyed. - Carolyn Scheppner
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