[PATCH 1/2] SCSI: run idle hctx after delay in scsi_mq_get_budget()

[Ming Lei]

If there isn't any outstanding request in this queue, both
blk-mq's RESTART and SCSI's builtin RESTART can't work,
so we have to deal with this case by running this queue
after delay.

Fixes: d04b6d97d0a1(scsi: implement .get_budget and .put_budget for blk-mq)
Signed-off-by: Ming Lei <ming....@redhat.com>
---
 drivers/scsi/scsi_lib.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 6f10afaca25b..08c495364b28 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1959,6 +1959,14 @@ static void scsi_mq_put_budget(struct blk_mq_hw_ctx 
*hctx)
        put_device(&sdev->sdev_gendev);
 }
 
+static void scsi_mq_run_idle_hctx(struct scsi_device *sdev,
+               struct blk_mq_hw_ctx *hctx)
+{
+       if (atomic_read(&sdev->device_busy) == 0 &&
+           !scsi_device_blocked(sdev))
+               blk_mq_delay_run_hw_queue(hctx, SCSI_QUEUE_DELAY);
+}
+
 static blk_status_t scsi_mq_get_budget(struct blk_mq_hw_ctx *hctx)
 {
        struct request_queue *q = hctx->queue;
@@ -1989,6 +1997,7 @@ static blk_status_t scsi_mq_get_budget(struct 
blk_mq_hw_ctx *hctx)
 out_put_device:
        put_device(&sdev->sdev_gendev);
 out:
+       scsi_mq_run_idle_hctx(sdev, hctx);
        return BLK_STS_RESOURCE;
 }
 
@@ -2039,9 +2048,7 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx 
*hctx,
        case BLK_STS_OK:
                break;
        case BLK_STS_RESOURCE:
-               if (atomic_read(&sdev->device_busy) == 0 &&
-                   !scsi_device_blocked(sdev))
-                       blk_mq_delay_run_hw_queue(hctx, SCSI_QUEUE_DELAY);
+               scsi_mq_run_idle_hctx(sdev, hctx);
                break;
        default:
                /*
-- 
2.9.5