blk-mq: start request gstate with gen 1

commit f4560231ec42092c6662acccabb28c6cac9f5dfb upstream.

rq->gstate and rq->aborted_gstate both are zero before rqs are
allocated. If we have a small timeout, when the timer fires,
there could be rqs that are never allocated, and also there could
be rq that has been allocated but not initialized and started. At
the moment, the rq->gstate and rq->aborted_gstate both are 0, thus
the blk_mq_terminate_expired will identify the rq is timed out and
invoke .timeout early.

For scsi, this will cause scsi_times_out to be invoked before the
scsi_cmnd is not initialized, scsi_cmnd->device is still NULL at
the moment, then we will get crash.

Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Martin Steigerwald <Martin@Lichtvoll.de>
Cc: stable@vger.kernel.org
Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/block/blk-core.c b/block/blk-core.c
index 3b489527c8f22f635407806decc12b8bf5a53f5b..34cbf50b303421670a7044d30d95af6b41bd66fa 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -129,6 +129,10 @@ void blk_rq_init(struct request_queue *q, struct request *rq)
        rq->part = NULL;
        seqcount_init(&rq->gstate_seq);
        u64_stats_init(&rq->aborted_gstate_sync);
+       /*
+        * See comment of blk_mq_init_request
+        */
+       WRITE_ONCE(rq->gstate, MQ_RQ_GEN_INC);
 }
 EXPORT_SYMBOL(blk_rq_init);
 

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 56e0c3699f9e01d43321c9e7fefa3bcca3f46595..96de7aa4f62ab214e5522e93dbf7a10da33efac9 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2076,6 +2076,13 @@ static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
 
        seqcount_init(&rq->gstate_seq);
        u64_stats_init(&rq->aborted_gstate_sync);
+       /*
+        * start gstate with gen 1 instead of 0, otherwise it will be equal
+        * to aborted_gstate, and be identified timed out by
+        * blk_mq_terminate_expired.
+        */
+       WRITE_ONCE(rq->gstate, MQ_RQ_GEN_INC);
+
        return 0;
 }