releases/4.14.28/scsi-ses-don-t-ask-for-diagnostic-pages-repeatedly-during-probe.patch

From foo@baz Fri Mar 16 15:43:17 CET 2018
From: Li Dongyang <dongyang.li@anu.edu.au>
Date: Tue, 14 Nov 2017 10:48:04 +1100
Subject: scsi: ses: don't ask for diagnostic pages repeatedly during probe

From: Li Dongyang <dongyang.li@anu.edu.au>


[ Upstream commit 9c0a50022b8ac7e863e6ec8342fa476fe5d1d75c ]

We are testing if there is a match with the ses device in a loop by
calling ses_match_to_enclosure(), which will issue scsi receive
diagnostics commands to the ses device for every device on the same
host.  On one of our boxes with 840 disks, it takes a long time to load
the driver:

[root@g1b-oss06 ~]# time modprobe ses

real	40m48.247s
user	0m0.001s
sys	0m0.196s

With the patch:

[root@g1b-oss06 ~]# time modprobe ses

real	0m17.915s
user	0m0.008s
sys	0m0.053s

Note that we still need to refresh page 10 when we see a new disk to
create the link.

Signed-off-by: Li Dongyang <dongyang.li@anu.edu.au>
Tested-by: Jason Ozolins <jason.ozolins@hpe.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/scsi/ses.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

--- a/drivers/scsi/ses.c
+++ b/drivers/scsi/ses.c
@@ -615,13 +615,16 @@ static void ses_enclosure_data_process(s
 }
 
 static void ses_match_to_enclosure(struct enclosure_device *edev,
-				   struct scsi_device *sdev)
+				   struct scsi_device *sdev,
+				   int refresh)
 {
+	struct scsi_device *edev_sdev = to_scsi_device(edev->edev.parent);
 	struct efd efd = {
 		.addr = 0,
 	};
 
-	ses_enclosure_data_process(edev, to_scsi_device(edev->edev.parent), 0);
+	if (refresh)
+		ses_enclosure_data_process(edev, edev_sdev, 0);
 
 	if (scsi_is_sas_rphy(sdev->sdev_target->dev.parent))
 		efd.addr = sas_get_address(sdev);
@@ -652,7 +655,7 @@ static int ses_intf_add(struct device *c
 		struct enclosure_device *prev = NULL;
 
 		while ((edev = enclosure_find(&sdev->host->shost_gendev, prev)) != NULL) {
-			ses_match_to_enclosure(edev, sdev);
+			ses_match_to_enclosure(edev, sdev, 1);
 			prev = edev;
 		}
 		return -ENODEV;
@@ -768,7 +771,7 @@ page2_not_supported:
 	shost_for_each_device(tmp_sdev, sdev->host) {
 		if (tmp_sdev->lun != 0 || scsi_device_enclosure(tmp_sdev))
 			continue;
-		ses_match_to_enclosure(edev, tmp_sdev);
+		ses_match_to_enclosure(edev, tmp_sdev, 0);
 	}
 
 	return 0;