linux-kernel - [PATCH 4.19 162/276] scsi: libsas: Do discovery on empty PHY to update PHY info

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Date:   Wed, 29 May 2019 20:05:20 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, John Garry <john.garry@...wei.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 162/276] scsi: libsas: Do discovery on empty PHY to update PHY info

[ Upstream commit d8649fc1c5e40e691d589ed825998c36a947491c ]

When we discover the PHY is empty in sas_rediscover_dev(), the PHY
information (like negotiated linkrate) is not updated.

As such, for a user examining sysfs for that PHY, they would see
incorrect values:

root@(none)$ cd /sys/class/sas_phy/phy-0:0:20
root@(none)$ more negotiated_linkrate
3.0 Gbit
root@(none)$ echo 0 > enable
root@(none)$ more negotiated_linkrate
3.0 Gbit

So fix this, simply discover the PHY again, even though we know it's empty;
in the above example, this gives us:

root@(none)$ more negotiated_linkrate
Phy disabled

We must do this after unregistering the device associated with the PHY
(in sas_unregister_devs_sas_addr()).

Signed-off-by: John Garry <john.garry@...wei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/scsi/libsas/sas_expander.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index e9ecc667e3fb4..231eb79efa320 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -2040,6 +2040,11 @@ static int sas_rediscover_dev(struct domain_device *dev, int phy_id, bool last)
 	if ((SAS_ADDR(sas_addr) == 0) || (res == -ECOMM)) {
 		phy->phy_state = PHY_EMPTY;
 		sas_unregister_devs_sas_addr(dev, phy_id, last);
+		/*
+		 * Even though the PHY is empty, for convenience we discover
+		 * the PHY to update the PHY info, like negotiated linkrate.
+		 */
+		sas_ex_phy_discover(dev, phy_id);
 		return res;
 	} else if (SAS_ADDR(sas_addr) == SAS_ADDR(phy->attached_sas_addr) &&
 		   dev_type_flutter(type, phy->attached_dev_type)) {
-- 
2.20.1