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| author | Jens Axboe <axboe@fb.com> | 2017-01-26 20:50:36 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2017-01-27 16:20:31 +0100 |
| commit | 3c782d67c16889d753a79a8da5422c583d7cfd51 (patch) | |
| tree | a34fce71ed855738dd53b3e66594446a23df7319 /block/blk-mq.c | |
| parent | blk-mq: improve scheduler queue sync/async running (diff) | |
| download | linux-3c782d67c16889d753a79a8da5422c583d7cfd51.tar.xz linux-3c782d67c16889d753a79a8da5422c583d7cfd51.zip | |
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>
Diffstat (limited to 'block/blk-mq.c')
| -rw-r--r-- | block/blk-mq.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index 1f948d5c2715..fd80101c7591 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -928,8 +928,16 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list) if (!blk_mq_get_driver_tag(rq, &hctx, false)) { if (!queued && reorder_tags_to_front(list)) continue; + + /* + * We failed getting a driver tag. Mark the queue(s) + * as needing a restart. Retry getting a tag again, + * in case the needed IO completed right before we + * marked the queue as needing a restart. + */ blk_mq_sched_mark_restart(hctx); - break; + if (!blk_mq_get_driver_tag(rq, &hctx, false)) + break; } list_del_init(&rq->queuelist); |