diff options
author | Jens Axboe <axboe@suse.de> | 2006-05-11 10:20:16 +0400 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-05-11 23:38:59 +0400 |
commit | dac07ec121de66b6be988b14ae2cd9ce45357b21 (patch) | |
tree | 95359f17d0857fd52f399cef072097523227d032 /block/ll_rw_blk.c | |
parent | f358166a9405e4f1d8e50d8f415c26d95505b6de (diff) | |
download | linux-dac07ec121de66b6be988b14ae2cd9ce45357b21.tar.xz |
[BLOCK] limit request_fn recursion
Don't recurse back into the driver even if the unplug threshold is met,
when the driver asks for a requeue. This is both silly from a logical
point of view (requeues typically happen due to driver/hardware
shortage), and also dangerous since we could hit an endless request_fn
-> requeue -> unplug -> request_fn loop and crash on stack overrun.
Also limit blk_run_queue() to one level of recursion, similar to how
blk_start_queue() works.
This patch fixed a real problem with SLES10 and lpfc, and it could hit
any SCSI lld that returns non-zero from it's ->queuecommand() handler.
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'block/ll_rw_blk.c')
-rw-r--r-- | block/ll_rw_blk.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index e5041a02e21f..eac48bec1479 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c @@ -1732,8 +1732,21 @@ void blk_run_queue(struct request_queue *q) spin_lock_irqsave(q->queue_lock, flags); blk_remove_plug(q); - if (!elv_queue_empty(q)) - q->request_fn(q); + + /* + * Only recurse once to avoid overrunning the stack, let the unplug + * handling reinvoke the handler shortly if we already got there. + */ + if (!elv_queue_empty(q)) { + if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { + q->request_fn(q); + clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags); + } else { + blk_plug_device(q); + kblockd_schedule_work(&q->unplug_work); + } + } + spin_unlock_irqrestore(q->queue_lock, flags); } EXPORT_SYMBOL(blk_run_queue); |