[SCSI] libsas: fix domain_device leak

Arrange for the deallocation of a struct domain_device object when it no
longer has:
1/ any children
2/ references by any scsi_targets
3/ references by a lldd

The comment about domain_device lifetime in
Documentation/scsi/libsas.txt is stale as it appears mainline never had
a version of a struct domain_device that was registered as a kobject.
We now manage domain_device reference counts on behalf of external
agents.

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

1 files changed, 24 insertions, 12 deletions

diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index 54a5199ceb56..4e649306ef4e 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -36,8 +36,6 @@
 
 void sas_init_dev(struct domain_device *dev)
 {
-        INIT_LIST_HEAD(&dev->siblings);
-        INIT_LIST_HEAD(&dev->dev_list_node);
         switch (dev->dev_type) {
         case SAS_END_DEV:
                 break;
@@ -73,14 +71,14 @@ static int sas_get_port_device(struct asd_sas_port *port)
         struct sas_rphy *rphy;
         struct domain_device *dev;
 
-        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+        dev = sas_alloc_device();
         if (!dev)
                 return -ENOMEM;
 
         spin_lock_irqsave(&port->phy_list_lock, flags);
         if (list_empty(&port->phy_list)) {
                 spin_unlock_irqrestore(&port->phy_list_lock, flags);
-                kfree(dev);
+                sas_put_device(dev);
                 return -ENODEV;
         }
         phy = container_of(port->phy_list.next, struct asd_sas_phy, port_phy_el);
@@ -130,7 +128,7 @@ static int sas_get_port_device(struct asd_sas_port *port)
         }
 
         if (!rphy) {
-                kfree(dev);
+                sas_put_device(dev);
                 return -ENODEV;
         }
         rphy->identify.phy_identifier = phy->phy->identify.phy_identifier;
@@ -173,6 +171,7 @@ int sas_notify_lldd_dev_found(struct domain_device *dev)
                                dev_name(sas_ha->dev),
                                SAS_ADDR(dev->sas_addr), res);
                 }
+                kref_get(&dev->kref);
         }
         return res;
 }
@@ -184,8 +183,10 @@ void sas_notify_lldd_dev_gone(struct domain_device *dev)
         struct Scsi_Host *shost = sas_ha->core.shost;
         struct sas_internal *i = to_sas_internal(shost->transportt);
 
-        if (i->dft->lldd_dev_gone)
+        if (i->dft->lldd_dev_gone) {
                 i->dft->lldd_dev_gone(dev);
+                sas_put_device(dev);
+        }
 }
 
 /* ---------- Common/dispatchers ---------- */
@@ -219,6 +220,20 @@ out_err2:
 
 /* ---------- Device registration and unregistration ---------- */
 
+void sas_free_device(struct kref *kref)
+{
+        struct domain_device *dev = container_of(kref, typeof(*dev), kref);
+
+        if (dev->parent)
+                sas_put_device(dev->parent);
+
+        /* 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);
+
+        kfree(dev);
+}
+
 static void sas_unregister_common_dev(struct asd_sas_port *port, struct domain_device *dev)
 {
         sas_notify_lldd_dev_gone(dev);
@@ -230,6 +245,8 @@ static void sas_unregister_common_dev(struct asd_sas_port *port, struct domain_d
         spin_lock_irq(&port->dev_list_lock);
         list_del_init(&dev->dev_list_node);
         spin_unlock_irq(&port->dev_list_lock);
+
+        sas_put_device(dev);
 }
 
 void sas_unregister_dev(struct asd_sas_port *port, struct domain_device *dev)
@@ -239,11 +256,6 @@ void sas_unregister_dev(struct asd_sas_port *port, struct domain_device *dev)
                 sas_rphy_delete(dev->rphy);
                 dev->rphy = NULL;
         }
-        if (dev->dev_type == EDGE_DEV || dev->dev_type == FANOUT_DEV) {
-                /* remove the phys and ports, everything else should be gone */
-                kfree(dev->ex_dev.ex_phy);
-                dev->ex_dev.ex_phy = NULL;
-        }
         sas_unregister_common_dev(port, dev);
 }
 
@@ -322,7 +334,7 @@ static void sas_discover_domain(struct work_struct *work)
                 list_del_init(&dev->dev_list_node);
                 spin_unlock_irq(&port->dev_list_lock);
 
-                kfree(dev); /* not kobject_register-ed yet */
+                sas_put_device(dev);
                 port->port_dev = NULL;
         }