net: factorize sync-rcu call in unregister_netdevice_many

Add dev_close_many and dev_deactivate_many to factorize another
sync-rcu operation on the netdevice unregister path.

$ modprobe dummy numdummies=10000
$ ip link set dev dummy* up
$ time rmmod dummy

Without the patch           With the patch

real    0m 24.63s           real    0m 5.15s
user    0m 0.00s            user    0m 0.00s
sys     0m 6.05s            sys     0m 5.14s

Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index ea1f8a83160d..786cc396cb4a 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -321,6 +321,7 @@ extern void dev_init_scheduler(struct net_device *dev);
 extern void dev_shutdown(struct net_device *dev);
 extern void dev_activate(struct net_device *dev);
 extern void dev_deactivate(struct net_device *dev);
+extern void dev_deactivate_many(struct list_head *head);
 extern struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
                                      struct Qdisc *qdisc);
 extern void qdisc_reset(struct Qdisc *qdisc);