From: Jason Yan <yanaijie@huawei.com>
Date: Tue, 25 Sep 2018 10:56:52 +0800
Subject: scsi: libsas: always unregister the old device if going to discover
 new
Patch-mainline: v4.20-rc1
Git-commit: 32c850bf587f993b2620b91e5af8a64a7813f504
References: FATE#326253

If we went into sas_rediscover_dev() the attached_sas_addr was already insured
not to be zero. So it's unnecessary to check if the attached_sas_addr is zero.

And although if the sas address is not changed, we always have to unregister
the old device when we are going to register a new one. We cannot just leave
the device there and bring up the new.

Signed-off-by: Jason Yan <yanaijie@huawei.com>
CC: chenxiang <chenxiang66@hisilicon.com>
CC: John Garry <john.garry@huawei.com>
CC: Johannes Thumshirn <jthumshirn@suse.de>
CC: Ewan Milne <emilne@redhat.com>
CC: Christoph Hellwig <hch@lst.de>
CC: Tomas Henzl <thenzl@redhat.com>
CC: Dan Williams <dan.j.williams@intel.com>
CC: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
---
 drivers/scsi/libsas/sas_expander.c |   13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -2054,14 +2054,11 @@ static int sas_rediscover_dev(struct dom
 		return res;
 	}
 
-	/* delete the old link */
-	if (SAS_ADDR(phy->attached_sas_addr) &&
-	    SAS_ADDR(sas_addr) != SAS_ADDR(phy->attached_sas_addr)) {
-		SAS_DPRINTK("ex %016llx phy 0x%x replace %016llx\n",
-			    SAS_ADDR(dev->sas_addr), phy_id,
-			    SAS_ADDR(phy->attached_sas_addr));
-		sas_unregister_devs_sas_addr(dev, phy_id, last);
-	}
+	/* we always have to delete the old device when we went here */
+	SAS_DPRINTK("ex %016llx phy 0x%x replace %016llx\n",
+		    SAS_ADDR(dev->sas_addr), phy_id,
+		    SAS_ADDR(phy->attached_sas_addr));
+	sas_unregister_devs_sas_addr(dev, phy_id, last);
 
 	return sas_discover_new(dev, phy_id);
 }