IPoIB: Fix deadlock between ipoib_open() and child interface create

Fix a deadlock between child interface creation/deletion and ipoib
start/stop.  The former takes vlan_mutex, and then might take RTNL via
register_netdev()/unregister_netdev().  The latter is executed with
RTNL held, and tries to take vlan_mutex, which can lead to an AB-BA
deadlock.

Fix this by having the child interface creation/deletion code take the
RTNL first so vlan_mutex always nests inside RTNL.  We can use
register_netdevice() for child interfaces because we form the
interface name from the parent interface and hence don't need the '%'
expansion of register_netdev().

Reported-by: Yossi Etigin <yosefe@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 8 insertions, 3 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
index 2cf1a4088718..5a76a5510350 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
@@ -61,6 +61,7 @@ int ipoib_vlan_add(struct net_device *pdev, unsigned short pkey)
 
         ppriv = netdev_priv(pdev);
 
+        rtnl_lock();
         mutex_lock(&ppriv->vlan_mutex);
 
         /*
@@ -111,7 +112,7 @@ int ipoib_vlan_add(struct net_device *pdev, unsigned short pkey)
                 goto device_init_failed;
         }
 
-        result = register_netdev(priv->dev);
+        result = register_netdevice(priv->dev);
         if (result) {
                 ipoib_warn(priv, "failed to initialize; error %i", result);
                 goto register_failed;
@@ -134,12 +135,13 @@ int ipoib_vlan_add(struct net_device *pdev, unsigned short pkey)
         list_add_tail(&priv->list, &ppriv->child_intfs);
 
         mutex_unlock(&ppriv->vlan_mutex);
+        rtnl_unlock();
 
         return 0;
 
 sysfs_failed:
         ipoib_delete_debug_files(priv->dev);
-        unregister_netdev(priv->dev);
+        unregister_netdevice(priv->dev);
 
 register_failed:
         ipoib_dev_cleanup(priv->dev);
@@ -149,6 +151,7 @@ device_init_failed:
 
 err:
         mutex_unlock(&ppriv->vlan_mutex);
+        rtnl_unlock();
         return result;
 }
 
@@ -162,10 +165,11 @@ int ipoib_vlan_delete(struct net_device *pdev, unsigned short pkey)
 
         ppriv = netdev_priv(pdev);
 
+        rtnl_lock();
         mutex_lock(&ppriv->vlan_mutex);
         list_for_each_entry_safe(priv, tpriv, &ppriv->child_intfs, list) {
                 if (priv->pkey == pkey) {
-                        unregister_netdev(priv->dev);
+                        unregister_netdevice(priv->dev);
                         ipoib_dev_cleanup(priv->dev);
                         list_del(&priv->list);
                         free_netdev(priv->dev);
@@ -175,6 +179,7 @@ int ipoib_vlan_delete(struct net_device *pdev, unsigned short pkey)
                 }
         }
         mutex_unlock(&ppriv->vlan_mutex);
+        rtnl_unlock();
 
         return ret;
 }