[PATCH v2 6/7] SRP transport: Port srp_wait_for_queuecommand() to scsi-mq

[Bart Van Assche]

Ensure that if scsi-mq is enabled that srp_wait_for_queuecommand()
waits until ongoing shost->hostt->queuecommand() calls have finished.

Signed-off-by: Bart Van Assche <bart.vanassche at sandisk.com>
Cc: James Bottomley <jejb at linux.vnet.ibm.com>
Cc: Martin K. Petersen <martin.petersen at oracle.com>
Cc: Doug Ledford <dledford at redhat.com>
---
 drivers/scsi/scsi_transport_srp.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c
index e3cd3ec..f1d580e 100644
--- a/drivers/scsi/scsi_transport_srp.c
+++ b/drivers/scsi/scsi_transport_srp.c
@@ -25,6 +25,7 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/delay.h>
+#include <linux/blk-mq.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_cmnd.h>
@@ -405,8 +406,6 @@ static void srp_reconnect_work(struct work_struct *work)
 /**
  * scsi_request_fn_active() - number of kernel threads inside scsi_request_fn()
  * @shost: SCSI host for which to count the number of scsi_request_fn() callers.
- *
- * To do: add support for scsi-mq in this function.
  */
 static int scsi_request_fn_active(struct Scsi_Host *shost)
 {
@@ -425,11 +424,28 @@ static int scsi_request_fn_active(struct Scsi_Host *shost)
 	return request_fn_active;
 }
 
+static void srp_mq_wait_for_queuecommand(struct Scsi_Host *shost)
+{
+	struct scsi_device *sdev;
+	struct request_queue *q;
+
+	shost_for_each_device(sdev, shost) {
+		q = sdev->request_queue;
+
+		blk_mq_quiesce_queue(q);
+		blk_mq_resume_queue(q);
+	}
+}
+
 /* Wait until ongoing shost->hostt->queuecommand() calls have finished. */
 static void srp_wait_for_queuecommand(struct Scsi_Host *shost)
 {
-	while (scsi_request_fn_active(shost))
-		msleep(20);
+	if (shost->use_blk_mq) {
+		srp_mq_wait_for_queuecommand(shost);
+	} else {
+		while (scsi_request_fn_active(shost))
+			msleep(20);
+	}
 }
 
 static void __rport_fail_io_fast(struct srp_rport *rport)
-- 
2.10.0