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As such, an RCU grace period passes > >> between the removal of the VRF slaves and the closing of the VRF device > >> until these functions are invoked. > >> > >> Therefore, it should not be possible for any concurrent RCU readers to > >> try and acquire a reference on the dst entry while we are potentially > >> releasing the last reference via dst_release(). > >> > >> Given the above, the synchronize_rcu() invocations in these functions > >> seem unnecessary and only add unnecessary delay when deleting VRF > >> devices. Remove them. > >> > >> Reviewed-by: Petr Machata > >> Signed-off-by: Ido Schimmel > >> --- > >> drivers/net/vrf.c | 2 -- > >> 1 file changed, 2 deletions(-) > >> > >> diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c > >> index bfc9ea91ac20..75edb8eba87f 100644 > >> --- a/drivers/net/vrf.c > >> +++ b/drivers/net/vrf.c > >> @@ -753,7 +753,6 @@ static void vrf_rt6_release(struct net_device *dev, struct net_vrf *vrf) > >> struct rt6_info *rt6 = rtnl_dereference(vrf->rt6); > >> > >> RCU_INIT_POINTER(vrf->rt6, NULL); > > > > We could argue that the vrf->rt6 clearing is not needed, > > or should be done before the RCU grace period mentioned in the > > changelog started ? > > > > AIUI Ido's point is that the synchronize_net() in > unregister_netdevice_many_notify() occurs before the ndo_uninit call > making the synchronize_rcu here unnecessary. There is also a second > synchronize_net after it. > > I get your point about skipping the clearing the poiniters. We can probably remove more code than just the synchronize_rcu() calls. Looking into that right now.