ipv6: mcast: remove one synchronize_net() barrier in ipv6_mc_down()

As discussed in the past (commit 2d3916f31891 ("ipv6: fix skb drops
in igmp6_event_query() and igmp6_event_report()")) I think the
synchronize_net() call in ipv6_mc_down() is not needed.

Under load, synchronize_net() can last between 200 usec and 5 ms.

KASAN seems to agree as well.

Fixes: f185de28d9ae ("mld: add new workqueues for process mld events")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Taehee Yoo <ap420073@gmail.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index bc6e0a0bad3c12d641a1dc60a8c790a6e72b1b5f..76ee1615ff2a07e1dd496aada377a7feb4703e8c 100644 (file)
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -2719,7 +2719,6 @@ void ipv6_mc_down(struct inet6_dev *idev)
        /* Should stop work after group drop. or we will
         * start work again in mld_ifc_event()
         */
-       synchronize_net();
        mld_query_stop_work(idev);
        mld_report_stop_work(idev);