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: 0b6abfeed5d8 ("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>