diff options
| author | Ming Lei <ming.lei@redhat.com> | 2021-09-06 14:50:03 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-09-12 19:32:43 -0600 |
| commit | 67f3b2f822b7e71cfc9b42dbd9f3144fa2933e0b (patch) | |
| tree | db190218a57bbeb6efbe1e3c8105f65cc91fe933 /block | |
| parent | 6880fa6c56601bb8ed59df6c30fd390cc5f6dd8f (diff) | |
blk-mq: avoid to iterate over stale request
blk-mq can't run allocating driver tag and updating ->rqs[tag]
atomically, meantime blk-mq doesn't clear ->rqs[tag] after the driver
tag is released.
So there is chance to iterating over one stale request just after the
tag is allocated and before updating ->rqs[tag].
scsi_host_busy_iter() calls scsi_host_check_in_flight() to count scsi
in-flight requests after scsi host is blocked, so no new scsi command can
be marked as SCMD_STATE_INFLIGHT. However, driver tag allocation still can
be run by blk-mq core. One request is marked as SCMD_STATE_INFLIGHT,
but this request may have been kept in another slot of ->rqs[], meantime
the slot can be allocated out but ->rqs[] isn't updated yet. Then this
in-flight request is counted twice as SCMD_STATE_INFLIGHT. This way causes
trouble in handling scsi error.
Fixes the issue by not iterating over stale request.
Cc: linux-scsi@vger.kernel.org
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Reported-by: luojiaxing <luojiaxing@huawei.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210906065003.439019-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-mq-tag.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 86f87346232a..ff5caeb82542 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -208,7 +208,7 @@ static struct request *blk_mq_find_and_get_req(struct blk_mq_tags *tags, spin_lock_irqsave(&tags->lock, flags); rq = tags->rqs[bitnr]; - if (!rq || !refcount_inc_not_zero(&rq->ref)) + if (!rq || rq->tag != bitnr || !refcount_inc_not_zero(&rq->ref)) rq = NULL; spin_unlock_irqrestore(&tags->lock, flags); return rq; |