[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, 24 insertions, 0 deletions

diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index c56cc640081..789b50861bb 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -147,6 +147,7 @@ static int sas_get_port_device(struct asd_sas_port *port)
 	memset(port->disc.eeds_a, 0, SAS_ADDR_SIZE);
 	memset(port->disc.eeds_b, 0, SAS_ADDR_SIZE);
 	port->disc.max_level = 0;
+	sas_device_set_phy(dev, port->port);
 
 	dev->rphy = rphy;
 
@@ -234,6 +235,9 @@ void sas_free_device(struct kref *kref)
 	if (dev->parent)
 		sas_put_device(dev->parent);
 
+	sas_port_put_phy(dev->phy);
+	dev->phy = NULL;
+
 	/* remove the phys and ports, everything else should be gone */
 	if (dev->dev_type == EDGE_DEV || dev->dev_type == FANOUT_DEV)
 		kfree(dev->ex_dev.ex_phy);
@@ -308,6 +312,26 @@ void sas_unregister_domain_devices(struct asd_sas_port *port)
 
 }
 
+void sas_device_set_phy(struct domain_device *dev, struct sas_port *port)
+{
+	struct sas_ha_struct *ha;
+	struct sas_phy *new_phy;
+
+	if (!dev)
+		return;
+
+	ha = dev->port->ha;
+	new_phy = sas_port_get_phy(port);
+
+	/* pin and record last seen phy */
+	spin_lock_irq(&ha->phy_port_lock);
+	if (new_phy) {
+		sas_port_put_phy(dev->phy);
+		dev->phy = new_phy;
+	}
+	spin_unlock_irq(&ha->phy_port_lock);
+}
+
 /* ---------- Discovery and Revalidation ---------- */
 
 /**