netdev - Re: [Patch net] ipv6: only call ip6_route_dev_notify() once for NETDEV

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Date:   Tue, 20 Jun 2017 23:16:29 -0400
From:   David Ahern <dsahern@...il.com>
To:     Cong Wang <xiyou.wangcong@...il.com>, netdev@...r.kernel.org
Cc:     jeffy.chen@...k-chips.com
Subject: Re: [Patch net] ipv6: only call ip6_route_dev_notify() once for
 NETDEV_UNREGISTER

On 6/20/17 2:42 PM, Cong Wang wrote:
> 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 <jeffy.chen@...k-chips.com>
> Cc: David Ahern <dsahern@...il.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
> ---
>  net/ipv6/route.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)

Acked-by: David Ahern <dsahern@...il.com>