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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Martin KaFai Lau <kafai@fb.com>
Cc: netdev <netdev@vger.kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH net 3/3] ipv6: Fix dst_entry refcnt bugs in ip6_tunnel
Date: Tue, 01 Sep 2015 14:26:58 -0700	[thread overview]
Message-ID: <1441142818.8932.185.camel@edumazet-glaptop2.roam.corp.google.com> (raw)
In-Reply-To: <20150901205505.GA66075@kafai-mba.local>

On Tue, 2015-09-01 at 13:55 -0700, Martin KaFai Lau wrote:
> On Tue, Sep 01, 2015 at 01:14:20PM -0700, Eric Dumazet wrote:
> > It should not be a problem. refcnt is taken when/if necessary (skb
> > queued on a qdisc for example)
> >
> > We have other uses of skb_dst_set_noref()
> >
> > Please describe the problem ?
> The current ip6_tnl_dst_get() does not take the dst refcnt.
> 
> If the dst is released after ip6_tnl_dst_get() and before
> skb_dst_set_noref(), would it cause an issue?

We are under rcu here, and a dst in a cache is protected by RCU by
definition.

skb_dst_set_noref() has following debugging clause, does it trigger for
you ?

WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());

  reply	other threads:[~2015-09-01 21:27 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-01 18:55 [PATCH net 0/3] ipv6: Fix dst_entry refcnt bugs in ip6_tunnel Martin KaFai Lau
2015-09-01 18:55 ` [PATCH net 1/3] ipv6: Refactor common ip6gre_tunnel_init codes Martin KaFai Lau
2015-09-01 18:55 ` [PATCH net 2/3] ipv6: Rename the dst_cache helper functions in ip6_tunnel Martin KaFai Lau
2015-09-01 18:55 ` [PATCH net 3/3] ipv6: Fix dst_entry refcnt bugs " Martin KaFai Lau
2015-09-01 20:14   ` Eric Dumazet
2015-09-01 20:55     ` Martin KaFai Lau
2015-09-01 21:26       ` Eric Dumazet [this message]
2015-09-01 22:25         ` Martin KaFai Lau
2015-09-01 22:38           ` Eric Dumazet
2015-09-02  0:31             ` Martin KaFai Lau
2015-09-02  0:42               ` Martin KaFai Lau
2015-09-02  1:02                 ` Martin KaFai Lau
2015-09-02  1:55     ` Martin KaFai Lau
2015-09-02 20:58     ` Martin KaFai Lau
2015-09-02 21:30       ` Eric Dumazet
2015-09-02 21:52         ` Martin KaFai Lau
2015-09-02 22:48           ` Eric Dumazet
2015-09-02 23:04             ` David Miller
2015-09-02 23:10             ` Martin KaFai Lau
2015-09-02 23:14               ` David Miller
2015-09-02 23:46               ` Eric Dumazet

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