tree c6d5444d06949edfd5d13fa0beed0992dd2ae469
parent 836413e8c78ecbc55aa31f3cb600f8ee1aa355a2
author Roland Dreier <roland@purestorage.com> 1353578411 -0800
committer Jens Axboe <axboe@kernel.dk> 1353677575 +0100

block: Don't access request after it might be freed

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>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>