4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Feras Daoud <ferasda@xxxxxxxxxxxx>
[ Upstream commit 1c3098cdb05207e740715857df7b0998e372f527 ]
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@xxxxxxxxxxxx>
Signed-off-by: Erez Shitrit <erezsh@xxxxxxxxxxxx>
Reviewed-by: Alex Vesker <valex@xxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/infiniband/ulp/ipoib/ipoib_vlan.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
@@ -185,7 +185,6 @@ int ipoib_vlan_delete(struct net_device
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;
@@ -193,6 +192,11 @@ int ipoib_vlan_delete(struct net_device
}
up_write(&ppriv->vlan_rwsem);
+ if (dev) {
+ ipoib_dbg(ppriv, "delete child vlan %s\n", dev->name);
+ unregister_netdevice(dev);
+ }
+
rtnl_unlock();
if (dev) {