IB/ipoib: Fix deadlock over vlan_mutex

This patch fixes Deadlock while executing ipoib_vlan_delete.

The function takes the vlan_rwsem semaphore and calls
unregister_netdevice. The later function calls
ipoib_mcast_stop_thread that cause workqueue flush.

When the queue has one of the ipoib_ib_dev_flush_xxx events,
a deadlock occur because these events also tries to catch the
same vlan_rwsem semaphore.

To fix, unregister_netdevice should be called after releasing
the semaphore.

Fixes: cbbe1efa4972 ("IPoIB: Fix deadlock between ipoib_open() and child interface create")
Signed-off-by: Feras Daoud <ferasda@mellanox.com>
Signed-off-by: Erez Shitrit <erezsh@mellanox.com>
Reviewed-by: Alex Vesker <valex@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
index fd811115af49ca23c4a5ebbcb3536c589fa056a0..96821838c352569fc87b1f89e32899eb50060332 100644 (file)
--- a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
@@ -196,7 +196,6 @@ int ipoib_vlan_delete(struct net_device *pdev, unsigned short pkey)
        list_for_each_entry_safe(priv, tpriv, &ppriv->child_intfs, list) {
                if (priv->pkey == pkey &&
                    priv->child_type == IPOIB_LEGACY_CHILD) {
-                       unregister_netdevice(priv->dev);
                        list_del(&priv->list);
                        dev = priv->dev;
                        break;
@@ -204,6 +203,11 @@ int ipoib_vlan_delete(struct net_device *pdev, unsigned short pkey)
        }
        up_write(&ppriv->vlan_rwsem);
 
+       if (dev) {
+               ipoib_dbg(ppriv, "delete child vlan %s\n", dev->name);
+               unregister_netdevice(dev);
+       }
+
        rtnl_unlock();
 
        if (dev) {