[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, 5 insertions, 2 deletions

diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index 5fdb63ad94b7..92f7e78a096c 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -284,9 +284,10 @@ static int smp_ata_check_ready(struct ata_link *link)
         struct ata_port *ap = link->ap;
         struct domain_device *dev = ap->private_data;
         struct domain_device *ex_dev = dev->parent;
-        struct sas_phy *phy = sas_find_local_phy(dev);
+        struct sas_phy *phy = sas_get_local_phy(dev);
 
         res = sas_get_phy_attached_sas_addr(ex_dev, phy->number, addr);
+        sas_put_local_phy(phy);
         /* break the wait early if the expander is unreachable,
          * otherwise keep polling
          */
@@ -319,10 +320,10 @@ static int sas_ata_hard_reset(struct ata_link *link, unsigned int *class,
                               unsigned long deadline)
 {
         int ret = 0, res;
+        struct sas_phy *phy;
         struct ata_port *ap = link->ap;
         int (*check_ready)(struct ata_link *link);
         struct domain_device *dev = ap->private_data;
-        struct sas_phy *phy = sas_find_local_phy(dev);
         struct sas_internal *i = dev_to_sas_internal(dev);
 
         res = i->dft->lldd_I_T_nexus_reset(dev);
@@ -330,10 +331,12 @@ static int sas_ata_hard_reset(struct ata_link *link, unsigned int *class,
         if (res != TMF_RESP_FUNC_COMPLETE)
                 SAS_DPRINTK("%s: Unable to reset ata device?\n", __func__);
 
+        phy = sas_get_local_phy(dev);
         if (scsi_is_sas_phy_local(phy))
                 check_ready = local_ata_check_ready;
         else
                 check_ready = smp_ata_check_ready;
+        sas_put_local_phy(phy);
 
         ret = ata_wait_after_reset(link, deadline, check_ready);
         if (ret && ret != -EAGAIN)