From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cong Wang Subject: [Patch net] ipv6: only call ip6_route_dev_notify() once for NETDEV_UNREGISTER Date: Tue, 20 Jun 2017 11:42:27 -0700 Message-ID: <1497984147-15011-1-git-send-email-xiyou.wangcong@gmail.com> Cc: jeffy.chen@rock-chips.com, Cong Wang , David Ahern To: netdev@vger.kernel.org Return-path: Received: from mail-pg0-f67.google.com ([74.125.83.67]:34287 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750951AbdFTSmg (ORCPT ); Tue, 20 Jun 2017 14:42:36 -0400 Received: by mail-pg0-f67.google.com with SMTP id j186so23262314pge.1 for ; Tue, 20 Jun 2017 11:42:36 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: In commit 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf") I assumed NETDEV_REGISTER and NETDEV_UNREGISTER are paired, unfortunately, as reported by jeffy, netdev_wait_allrefs() could rebroadcast NETDEV_UNREGISTER event until all refs are gone. We have to add an additional check to avoid this corner case. For netdev_wait_allrefs() dev->reg_state is NETREG_UNREGISTERED, for dev_change_net_namespace(), dev->reg_state is NETREG_REGISTERED. So check for dev->reg_state != NETREG_UNREGISTERED. Fixes: 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf") Reported-by: jeffy Cc: David Ahern Signed-off-by: Cong Wang --- net/ipv6/route.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 7cebd95..322bd62 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -3722,7 +3722,11 @@ static int ip6_route_dev_notify(struct notifier_block *this, net->ipv6.ip6_blk_hole_entry->dst.dev = dev; net->ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(dev); #endif - } else if (event == NETDEV_UNREGISTER) { + } else if (event == NETDEV_UNREGISTER && + dev->reg_state != NETREG_UNREGISTERED) { + /* NETDEV_UNREGISTER could be fired for multiple times by + * netdev_wait_allrefs(). Make sure we only call this once. + */ in6_dev_put(net->ipv6.ip6_null_entry->rt6i_idev); #ifdef CONFIG_IPV6_MULTIPLE_TABLES in6_dev_put(net->ipv6.ip6_prohibit_entry->rt6i_idev); -- 2.5.5