[SCSI] libsas: Clean up discovery failure handler code

sas_rphy_delete does two things: it removes the sas_rphy from the transport
layer and frees the sas_rphy.  This can be broken down into two functions,
sas_rphy_remove and sas_rphy_free; sas_rphy_remove is of interest to
sas_discover_root_expander because it calls functions that require
sas_rphy_add as a prerequisite and can fail (namely sas_discover_expander).
In that case, sas_discover_root_expander needs to be able to undo the effects
of sas_rphy_add yet leave the job of freeing the sas_rphy to the caller of
sas_discover_root_expander.

This patch also removes some unnecessary code from sas_discover_end_dev
to eliminate an unnecessary cycle of sas_notify_lldd_gone/found for SAS
devices, thus eliminating a sas_rphy_remove call (and fixing a race condition
where a SCSI target scan can come in between the gone and found call).
It also moves the sas_rphy_free calls into sas_discover_domain and
sas_ex_discover_end_dev to complement the sas_rphy_allocation via
sas_get_port_device.

This patch does not change the semantics of sas_rphy_delete.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

3 files changed, 39 insertions, 47 deletions

diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index b6ba0e053d1a..a65598b1e536 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -577,8 +577,6 @@ int sas_discover_sata(struct domain_device *dev)
 out_err:
         sas_notify_lldd_dev_gone(dev);
 out_err2:
-        sas_rphy_free(dev->rphy);
-        dev->rphy = NULL;
         return res;
 }
 
@@ -600,24 +598,11 @@ int sas_discover_end_dev(struct domain_device *dev)
         if (res)
                 goto out_err;
 
-        /* do this to get the end device port attributes which will have
-         * been scanned in sas_rphy_add */
-        sas_notify_lldd_dev_gone(dev);
-        res = sas_notify_lldd_dev_found(dev);
-        if (res)
-                goto out_err3;
-
         return 0;
 
 out_err:
         sas_notify_lldd_dev_gone(dev);
 out_err2:
-        sas_rphy_free(dev->rphy);
-        dev->rphy = NULL;
-        return res;
-out_err3:
-        sas_rphy_delete(dev->rphy);
-        dev->rphy = NULL;
         return res;
 }
 
@@ -672,6 +657,7 @@ void sas_unregister_domain_devices(struct asd_sas_port *port)
  */
 static void sas_discover_domain(struct work_struct *work)
 {
+        struct domain_device *dev;
         int error = 0;
         struct sas_discovery_event *ev =
                 container_of(work, struct sas_discovery_event, work);
@@ -681,39 +667,42 @@ static void sas_discover_domain(struct work_struct *work)
                         &port->disc.pending);
 
         if (port->port_dev)
-                return ;
-        else {
-                error = sas_get_port_device(port);
-                if (error)
-                        return;
-        }
+                return;
+
+        error = sas_get_port_device(port);
+        if (error)
+                return;
+        dev = port->port_dev;
 
         SAS_DPRINTK("DOING DISCOVERY on port %d, pid:%d\n", port->id,
                     current->pid);
 
-        switch (port->port_dev->dev_type) {
+        switch (dev->dev_type) {
         case SAS_END_DEV:
-                error = sas_discover_end_dev(port->port_dev);
+                error = sas_discover_end_dev(dev);
                 break;
         case EDGE_DEV:
         case FANOUT_DEV:
-                error = sas_discover_root_expander(port->port_dev);
+                error = sas_discover_root_expander(dev);
                 break;
         case SATA_DEV:
         case SATA_PM:
-                error = sas_discover_sata(port->port_dev);
+                error = sas_discover_sata(dev);
                 break;
         default:
-                SAS_DPRINTK("unhandled device %d\n", port->port_dev->dev_type);
+                SAS_DPRINTK("unhandled device %d\n", dev->dev_type);
                 break;
         }
 
         if (error) {
+                sas_rphy_free(dev->rphy);
+                dev->rphy = NULL;
+
                 spin_lock(&port->dev_list_lock);
-                list_del_init(&port->port_dev->dev_list_node);
+                list_del_init(&dev->dev_list_node);
                 spin_unlock(&port->dev_list_lock);
 
-                kfree(port->port_dev); /* not kobject_register-ed yet */
+                kfree(dev); /* not kobject_register-ed yet */
                 port->port_dev = NULL;
         }
 
diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index 0dfd97e7e96c..d9b9a008d36d 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -667,6 +667,8 @@ static struct domain_device *sas_ex_discover_end_dev(
         return child;
 
  out_list_del:
+        sas_rphy_free(child->rphy);
+        child->rphy = NULL;
         list_del(&child->dev_list_node);
  out_free:
         sas_port_delete(phy->port);
@@ -1444,12 +1446,8 @@ int sas_discover_root_expander(struct domain_device *dev)
         return res;
 
 out_err2:
-        sas_rphy_delete(dev->rphy);
-        dev->rphy = NULL;
-        return res;
+        sas_rphy_remove(dev->rphy);
 out_err:
-        sas_rphy_free(dev->rphy);
-        dev->rphy = NULL;
         return res;
 }
 
diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c
index ce232803f433..010845fd2b85 100644
--- a/drivers/scsi/scsi_transport_sas.c
+++ b/drivers/scsi/scsi_transport_sas.c
@@ -1299,7 +1299,7 @@ EXPORT_SYMBOL(sas_rphy_add);
  * Note:
  *   This function must only be called on a remote
  *   PHY that has not sucessfully been added using
- *   sas_rphy_add().
+ *   sas_rphy_add() (or has been sas_rphy_remove()'d)
  */
 void sas_rphy_free(struct sas_rphy *rphy)
 {
@@ -1318,18 +1318,30 @@ void sas_rphy_free(struct sas_rphy *rphy)
 EXPORT_SYMBOL(sas_rphy_free);
 
 /**
- * sas_rphy_delete  --  remove SAS remote PHY
- * @rphy:       SAS remote PHY to remove
+ * sas_rphy_delete  --  remove and free SAS remote PHY
+ * @rphy:       SAS remote PHY to remove and free
  *
- * Removes the specified SAS remote PHY.
+ * Removes the specified SAS remote PHY and frees it.
  */
 void
 sas_rphy_delete(struct sas_rphy *rphy)
 {
+        sas_rphy_remove(rphy);
+        sas_rphy_free(rphy);
+}
+EXPORT_SYMBOL(sas_rphy_delete);
+
+/**
+ * sas_rphy_remove  --  remove SAS remote PHY
+ * @rphy:       SAS remote phy to remove
+ *
+ * Removes the specified SAS remote PHY.
+ */
+void
+sas_rphy_remove(struct sas_rphy *rphy)
+{
         struct device *dev = &rphy->dev;
         struct sas_port *parent = dev_to_sas_port(dev->parent);
-        struct Scsi_Host *shost = dev_to_shost(parent->dev.parent);
-        struct sas_host_attrs *sas_host = to_sas_host_attrs(shost);
 
         switch (rphy->identify.device_type) {
         case SAS_END_DEVICE:
@@ -1345,17 +1357,10 @@ sas_rphy_delete(struct sas_rphy *rphy)
 
         transport_remove_device(dev);
         device_del(dev);
-        transport_destroy_device(dev);
-
-        mutex_lock(&sas_host->lock);
-        list_del(&rphy->list);
-        mutex_unlock(&sas_host->lock);
 
         parent->rphy = NULL;
-
-        put_device(dev);
 }
-EXPORT_SYMBOL(sas_rphy_delete);
+EXPORT_SYMBOL(sas_rphy_remove);
 
 /**
  * scsi_is_sas_rphy  --  check if a struct device represents a SAS remote PHY