blk-mq: fix potential race in queue restart and driver tag allocation
authorJens Axboe <axboe@fb.com>
Thu, 26 Jan 2017 19:50:36 +0000 (12:50 -0700)
committerJens Axboe <axboe@fb.com>
Fri, 27 Jan 2017 15:20:31 +0000 (08:20 -0700)
commit3c782d67c16889d753a79a8da5422c583d7cfd51
treea34fce71ed855738dd53b3e66594446a23df7319
parent0abad774124351ba211b9053786ebd5a5a722d53
blk-mq: fix potential race in queue restart and driver tag allocation

Once we mark the queue as needing a restart, re-check if we can
get a driver tag. This fixes a theoretical issue where the needed
IO completes _after_ blk_mq_get_driver_tag() fails, but before we
manage to set the restart bit.

Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Tested-by: Hannes Reinecke <hare@suse.com>
block/blk-mq.c