diff options
| author | Roland Dreier <roland@purestorage.com> | 2012-11-22 02:00:11 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-03-11 16:10:06 -0700 |
| commit | 0ef4c881e4ade7a45174d9cf45eca6f9e10f5ccc (patch) | |
| tree | 36131ba5152ad6b4fb076541076a2d386393e363 /block/blk-exec.c | |
| parent | 50e97121b728014dfbc34f07d1ac5a507466a2b7 (diff) | |
block: Don't access request after it might be freed
commit 893d290f1d7496db97c9471bc352ad4a11dc8a25 upstream.
After we've done __elv_add_request() and __blk_run_queue() in
blk_execute_rq_nowait(), the request might finish and be freed
immediately. Therefore checking if the type is REQ_TYPE_PM_RESUME
isn't safe afterwards, because if it isn't, rq might be gone.
Instead, check beforehand and stash the result in a temporary.
This fixes crashes in blk_execute_rq_nowait() I get occasionally when
running with lots of memory debugging options enabled -- I think this
race is usually harmless because the window for rq to be reallocated
is so small.
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[xr: Backported to 3.4: adjust context]
Signed-off-by: Rui Xiang <rui.xiang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'block/blk-exec.c')
| -rw-r--r-- | block/blk-exec.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/block/blk-exec.c b/block/blk-exec.c index fb2cbd55162..1b5cb66ef85 100644 --- a/block/blk-exec.c +++ b/block/blk-exec.c @@ -49,8 +49,18 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk, rq_end_io_fn *done) { int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; + bool is_pm_resume; WARN_ON(irqs_disabled()); + + rq->rq_disk = bd_disk; + rq->end_io = done; + /* + * need to check this before __blk_run_queue(), because rq can + * be freed before that returns. + */ + is_pm_resume = rq->cmd_type == REQ_TYPE_PM_RESUME; + spin_lock_irq(q->queue_lock); if (unlikely(blk_queue_dead(q))) { @@ -66,7 +76,7 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk, __elv_add_request(q, rq, where); __blk_run_queue(q); /* the queue is stopped so it won't be run */ - if (rq->cmd_type == REQ_TYPE_PM_RESUME) + if (is_pm_resume) q->request_fn(q); spin_unlock_irq(q->queue_lock); } |