[PATCH 5.18 504/879] scsi: hisi_sas: Fix rescan after deleting a disk

Greg Kroah-Hartman
2022-06-08T00:56:00Z

From: John Garry <john.garry@huawei.com>

[ Upstream commit e9dedc13bb11bc553754abecb322e5e41d1b4fef ]

Removing an ATA device via sysfs means that the device may not be found
through re-scanning:

root@ubuntu:/home/john# lsscsi
[0:0:0:0] disk SanDisk LT0200MO P404 /dev/sda
[0:0:1:0] disk ATA HGST HUS724040AL A8B0 /dev/sdb
[0:0:8:0] enclosu 12G SAS Expander RevB -
root@ubuntu:/home/john# echo 1 > /sys/block/sdb/device/delete
root@ubuntu:/home/john# echo "- - -" > /sys/class/scsi_host/host0/scan
root@ubuntu:/home/john# lsscsi
[0:0:0:0] disk SanDisk LT0200MO P404 /dev/sda
[0:0:8:0] enclosu 12G SAS Expander RevB -
root@ubuntu:/home/john#

The problem is that the rescan of the device may conflict with the device
in being re-initialized, as follows:

- In the rescan we call hisi_sas_slave_alloc() in store_scan() ->
sas_user_scan() -> [__]scsi_scan_target() -> scsi_probe_and_add_lunc()
-> scsi_alloc_sdev() -> hisi_sas_slave_alloc() -> hisi_sas_init_device()
In hisi_sas_init_device() we issue an IT nexus reset for ATA devices

- That IT nexus causes the remote PHY to go down and this triggers a bcast
event

- In parallel libsas processes the bcast event, finds that the phy is down
and marks the device as gone

The hard reset issued in hisi_sas_init_device() is unncessary - as
described in the code comment - so remove it. Also set dev status as
HISI_SAS_DEV_NORMAL as the hisi_sas_init_device() call.

Link: https://lore.kernel.org/r/1652354134-171343-4-git-send-email-john.garry@huawei.com
Fixes: 36c6b7613ef1 ("scsi: hisi_sas: Initialise devices in .slave_alloc callback")
Tested-by: Yihang Li <liyihang6@hisilicon.com>
Reviewed-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/hisi_sas/hisi_sas_main.c | 47 ++++++++++-----------------
1 file changed, 18 insertions(+), 29 deletions(-)

diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c
index 4bda2f6cb352..86cbfab78dfe 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_main.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
@@ -709,8 +709,6 @@ static int hisi_sas_init_device(struct domain_device *device)
struct scsi_lun lun;
int retry = HISI_SAS_DISK_RECOVER_CNT;
struct hisi_hba *hisi_hba = dev_to_hisi_hba(device);
- struct device *dev = hisi_hba->dev;
- struct sas_phy *local_phy;

switch (device->dev_type) {
case SAS_END_DEVICE:
@@ -729,30 +727,18 @@ static int hisi_sas_init_device(struct domain_device *device)
case SAS_SATA_PM_PORT:
case SAS_SATA_PENDING:
/*
- * send HARD RESET to clear previous affiliation of
- * STP target port
+ * If an expander is swapped when a SATA disk is attached then
+ * we should issue a hard reset to clear previous affiliation
+ * of STP target port, see SPL (chapter 6.19.4).
+ *
+ * However we don't need to issue a hard reset here for these
+ * reasons:
+ * a. When probing the device, libsas/libata already issues a
+ * hard reset in sas_probe_sata() -> ata_sas_async_probe().
+ * Note that in hisi_sas_debug_I_T_nexus_reset() we take care
+ * to issue a hard reset by checking the dev status (== INIT).
+ * b. When resetting the controller, this is simply unnecessary.
*/
- local_phy = sas_get_local_phy(device);
- if (!scsi_is_sas_phy_local(local_phy) &&
- !test_bit(HISI_SAS_RESETTING_BIT, &hisi_hba->flags)) {
- unsigned long deadline = ata_deadline(jiffies, 20000);
- struct sata_device *sata_dev = &device->sata_dev;
- struct ata_host *ata_host = sata_dev->ata_host;
- struct ata_port_operations *ops = ata_host->ops;
- struct ata_port *ap = sata_dev->ap;
- struct ata_link *link;
- unsigned int classes;
-
- ata_for_each_link(link, ap, EDGE)
- rc = ops->hardreset(link, &classes,
- deadline);
- }
- sas_put_local_phy(local_phy);
- if (rc) {
- dev_warn(dev, "SATA disk hardreset fail: %d\n", rc);
- return rc;
- }
-
while (retry-- > 0) {
rc = hisi_sas_softreset_ata_disk(device);
if (!rc)
@@ -768,15 +754,19 @@ static int hisi_sas_init_device(struct domain_device *device)

int hisi_sas_slave_alloc(struct scsi_device *sdev)
{
- struct domain_device *ddev;
+ struct domain_device *ddev = sdev_to_domain_dev(sdev);
+ struct hisi_sas_device *sas_dev = ddev->lldd_dev;
int rc;

rc = sas_slave_alloc(sdev);
if (rc)
return rc;
- ddev = sdev_to_domain_dev(sdev);

- return hisi_sas_init_device(ddev);
+ rc = hisi_sas_init_device(ddev);
+ if (rc)
+ return rc;
+ sas_dev->dev_status = HISI_SAS_DEV_NORMAL;
+ return 0;
}
EXPORT_SYMBOL_GPL(hisi_sas_slave_alloc);

@@ -826,7 +816,6 @@ static int hisi_sas_dev_found(struct domain_device *device)
dev_info(dev, "dev[%d:%x] found\n",
sas_dev->device_id, sas_dev->dev_type);

- sas_dev->dev_status = HISI_SAS_DEV_NORMAL;
return 0;

err_out:
--
2.35.1