[SCSI] libsas: fix sas_find_local_phy(), take phy references

In the direct-attached case this routine returns the phy on which this
device was first discovered.  Which is broken if we want to support
wide-targets, as this phy reference can become stale even though the
port is still active.

In the expander-attached case this routine tries to lookup the phy by
scanning the attached sas addresses of the parent expander, and BUG_ONs
if it can't find it.  However since eh and the libsas workqueue run
independently we can still be attempting device recovery via eh after
libsas has recorded the device as detached.  This is even easier to hit
now that eh is blocked while device domain rediscovery takes place, and
that libata is fed more timed out commands increasing the chances that
it will try to recover the ata device.

Arrange for dev->phy to always point to a last known good phy, it may be
stale after the port is torn down, but it will catch up for wide port
reconfigurations, and never be NULL.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index 6fb1f3afd1e0..68a80a00f73f 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -723,6 +723,7 @@ static struct domain_device *sas_ex_discover_end_dev(
                 }
         }
         sas_ex_get_linkrate(parent, child, phy);
+        sas_device_set_phy(child, phy->port);
 
 #ifdef CONFIG_SCSI_SAS_ATA
         if ((phy->attached_tproto & SAS_PROTOCOL_STP) || phy->attached_sata_dev) {
@@ -1810,7 +1811,7 @@ static void sas_unregister_devs_sas_addr(struct domain_device *parent,
 {
         struct expander_device *ex_dev = &parent->ex_dev;
         struct ex_phy *phy = &ex_dev->ex_phy[phy_id];
-        struct domain_device *child, *n;
+        struct domain_device *child, *n, *found = NULL;
         if (last) {
                 list_for_each_entry_safe(child, n,
                         &ex_dev->children, siblings) {
@@ -1822,6 +1823,7 @@ static void sas_unregister_devs_sas_addr(struct domain_device *parent,
                                         sas_unregister_ex_tree(parent->port, child);
                                 else
                                         sas_unregister_dev(parent->port, child);
+                                found = child;
                                 break;
                         }
                 }
@@ -1830,6 +1832,7 @@ static void sas_unregister_devs_sas_addr(struct domain_device *parent,
         memset(phy->attached_sas_addr, 0, SAS_ADDR_SIZE);
         if (phy->port) {
                 sas_port_delete_phy(phy->port, phy->phy);
+                sas_device_set_phy(found, phy->port);
                 if (phy->port->num_phys == 0)
                         sas_port_delete(phy->port);
                 phy->port = NULL;