In scsi core, __scsi_queue_insert should just put request back on
the queue and retry using the same command as before. However, for
blk-mq, scsi_mq_requeue_cmd is employed here which will unprepare
the request. To align with the semantics of __scsi_queue_insert,
use blk_mq_requeue_request with kick_requeue_list == true and put
the reference of scsi_device.
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx>
Reviewed-by: Bart Van Assche <bart.vanassche@xxxxxxx>
---
Changelog:
V3 -> V4:
- modify the comment and make it more clearly
V2 -> V3:
- add comment to explain why we need a put_device in
__scsi_queue_insert
- add reviewed-by
V1 -> V2:
- add put_device on scsi_device->sdev_gendev
drivers/scsi/scsi_lib.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index a86df9c..6ce33f6 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -191,7 +191,19 @@ static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, bool unbusy)
*/
cmd->result = 0;
if (q->mq_ops) {
- scsi_mq_requeue_cmd(cmd);
+ /*
+ * Before a SCSI command is dispatched,
+ * get_device(&sdev->sdev_gendev) is called and the host,
+ * target and device busy counters are increased. Since
+ * requeuing a request causes these actions to be repeated and
+ * since scsi_device_unbusy() has already been called,
+ * put_device(&device->sdev_gendev) must still be called. Call
+ * put_device() after blk_mq_requeue_request() to avoid that
+ * removal of the SCSI device can start before requeueing has
+ * happened.
+ */
+ blk_mq_requeue_request(cmd->request, true);
+ put_device(&device->sdev_gendev);
return;
}
spin_lock_irqsave(q->queue_lock, flags);
--
2.7.4
