netdev - Re: [Patch net 2/2] ipmr,ip6mr: call list_del_rcu() when deleting mr table from list

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Date:	Wed, 25 Mar 2015 21:07:02 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Cong Wang <xiyou.wangcong@...il.com>, netdev@...r.kernel.org
Subject: Re: [Patch net 2/2] ipmr,ip6mr: call list_del_rcu() when deleting mr
 table from list



On Wed, Mar 25, 2015, at 20:05, Cong Wang wrote:
> Probably not a big deal, just for corretness.
> 
> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
> ---
>  net/ipv4/ipmr.c  | 2 +-
>  net/ipv6/ip6mr.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
> index d6fede8..68f67b8 100644
> --- a/net/ipv4/ipmr.c
> +++ b/net/ipv4/ipmr.c
> @@ -280,7 +280,7 @@ static void __net_exit ipmr_rules_exit(struct net
> *net)
>  
>  	rtnl_lock();
>  	list_for_each_entry_safe(mrt, next, &net->ipv4.mr_tables, list) {
> -               list_del(&mrt->list);
> +               list_del_rcu(&mrt->list);
>  		ipmr_free_table(mrt);
>  	}
>  	rtnl_unlock();

I really do wonder if we have the rcu locking correct in there:

Looking into getsockopt/setsockopt operations, we might have socket
lock, but I cannot see where we lock rcu, so the ipmr_get_table call is
safe. Do you also see the problem?

Thanks,
Hannes
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