SCSI: fix queue cleanup race before queue initialization is done

[mirror_ubuntu-bionic-kernel.git] / drivers / scsi / scsi_lib.c

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index e44d641f74c1f9b7e0bc5528102b4020a3e14f76..f75330d1430e132a46f2c52c7a6208e05e45bc86 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -683,6 +683,12 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
                 */
                scsi_mq_uninit_cmd(cmd);
 
+               /*
+                * queue is still alive, so grab the ref for preventing it
+                * from being cleaned up during running queue.
+                */
+               percpu_ref_get(&q->q_usage_counter);
+
                __blk_mq_end_request(req, error);
 
                if (scsi_target(sdev)->single_lun ||
@@ -690,6 +696,8 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
                        kblockd_schedule_work(&sdev->requeue_work);
                else
                        blk_mq_run_hw_queues(q, true);
+
+               percpu_ref_put(&q->q_usage_counter);
        } else {
                unsigned long flags;