[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, 6 insertions, 4 deletions

diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index 1b831c55ec6e..15d2239a378b 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -657,10 +657,11 @@ static struct domain_device *sas_ex_discover_end_dev(
         if (phy->attached_sata_host || phy->attached_sata_ps)
                 return NULL;
 
-        child = kzalloc(sizeof(*child), GFP_KERNEL);
+        child = sas_alloc_device();
         if (!child)
                 return NULL;
 
+        kref_get(&parent->kref);
         child->parent = parent;
         child->port   = parent->port;
         child->iproto = phy->attached_iproto;
@@ -762,7 +763,7 @@ static struct domain_device *sas_ex_discover_end_dev(
         sas_port_delete(phy->port);
  out_err:
         phy->port = NULL;
-        kfree(child);
+        sas_put_device(child);
         return NULL;
 }
 
@@ -809,7 +810,7 @@ static struct domain_device *sas_ex_discover_expander(
                             phy->attached_phy_id);
                 return NULL;
         }
-        child = kzalloc(sizeof(*child), GFP_KERNEL);
+        child = sas_alloc_device();
         if (!child)
                 return NULL;
 
@@ -835,6 +836,7 @@ static struct domain_device *sas_ex_discover_expander(
         child->rphy = rphy;
         edev = rphy_to_expander_device(rphy);
         child->dev_type = phy->attached_dev_type;
+        kref_get(&parent->kref);
         child->parent = parent;
         child->port = port;
         child->iproto = phy->attached_iproto;
@@ -858,7 +860,7 @@ static struct domain_device *sas_ex_discover_expander(
                 spin_lock_irq(&parent->port->dev_list_lock);
                 list_del(&child->dev_list_node);
                 spin_unlock_irq(&parent->port->dev_list_lock);
-                kfree(child);
+                sas_put_device(child);
                 return NULL;
         }
         list_add_tail(&child->siblings, &parent->ex_dev.children);