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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     Li Dongyang <dongyang.li@anu.edu.au>,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.9 196/219] scsi: ses: don't ask for diagnostic
 pages repeatedly during probe
Thread-Topic: [PATCH AUTOSEL for 4.9 196/219] scsi: ses: don't ask for
 diagnostic pages repeatedly during probe
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Date:   Sat, 3 Mar 2018 22:29:50 +0000
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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>
---
 drivers/scsi/ses.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c
index f1cdf32d7514..69046d342bc5 100644
--- a/drivers/scsi/ses.c
+++ b/drivers/scsi/ses.c
@@ -578,13 +578,16 @@ static void ses_enclosure_data_process(struct enclosu=
re_device *edev,
 }
=20
 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 =3D to_scsi_device(edev->edev.parent);
 	struct efd efd =3D {
 		.addr =3D 0,
 	};
=20
-	ses_enclosure_data_process(edev, to_scsi_device(edev->edev.parent), 0);
+	if (refresh)
+		ses_enclosure_data_process(edev, edev_sdev, 0);
=20
 	if (scsi_is_sas_rphy(sdev->sdev_target->dev.parent))
 		efd.addr =3D sas_get_address(sdev);
@@ -615,7 +618,7 @@ static int ses_intf_add(struct device *cdev,
 		struct enclosure_device *prev =3D NULL;
=20
 		while ((edev =3D enclosure_find(&sdev->host->shost_gendev, prev)) !=3D N=
ULL) {
-			ses_match_to_enclosure(edev, sdev);
+			ses_match_to_enclosure(edev, sdev, 1);
 			prev =3D edev;
 		}
 		return -ENODEV;
@@ -727,7 +730,7 @@ static int ses_intf_add(struct device *cdev,
 	shost_for_each_device(tmp_sdev, sdev->host) {
 		if (tmp_sdev->lun !=3D 0 || scsi_device_enclosure(tmp_sdev))
 			continue;
-		ses_match_to_enclosure(edev, tmp_sdev);
+		ses_match_to_enclosure(edev, tmp_sdev, 0);
 	}
=20
 	return 0;
--=20
2.14.1