Description of problem:

This fix is needed to run openvswitch 2.1.0 on Fedora 20.

commit 4f647e0a3c37b8d5086214128614a136064110c3
Author: Flavio Leitner <fbl>
Date:   Thu Mar 27 11:05:34 2014 -0300

    openvswitch: fix a possible deadlock and lockdep warning
    
    There are two problematic situations.
    
    A deadlock can happen when is_percpu is false because it can get
    interrupted while holding the spinlock. Then it executes
    ovs_flow_stats_update() in softirq context which tries to get
    the same lock.
    
    The second sitation is that when is_percpu is true, the code
    correctly disables BH but only for the local CPU, so the
    following can happen when locking the remote CPU without
    disabling BH:
    
           CPU#0                            CPU#1
      ovs_flow_stats_get()
       stats_read()
     +->spin_lock remote CPU#1        ovs_flow_stats_get()
     |  <interrupted>                  stats_read()
     |  ...                       +-->  spin_lock remote CPU#0
     |                            |     <interrupted>
     |  ovs_flow_stats_update()   |     ...
     |   spin_lock local CPU#0 <--+     ovs_flow_stats_update()
     +---------------------------------- spin_lock local CPU#1
    
    This patch disables BH for both cases fixing the deadlocks.
    Acked-by: Jesse Gross <jesse>
[...]   
    Signed-off-by: Flavio Leitner <fbl>
    Signed-off-by: David S. Miller <davem>