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SubjectRe: [PATCH net] ipv6: add complete rcu protection around np->opt
Date
On Tue, Dec 1, 2015, at 14:05, Eric Dumazet wrote:
> On Tue, 2015-12-01 at 12:11 +0100, Hannes Frederic Sowa wrote:
> > Hi Eric,
> >
> > On Mon, Nov 30, 2015, at 04:37, Eric Dumazet wrote:
> > > - opt = xchg(&np->opt, NULL);
> > > - if (opt)
> > > - sock_kfree_s(sk, opt, opt->tot_len);
> > > + opt = xchg((__force struct ipv6_txoptions
> > > **)&np->opt,
> > > + NULL);
> > > + if (opt) {
> > > + atomic_sub(opt->tot_len,
> > > &sk->sk_omem_alloc);
> > > + txopt_put(opt);
> > > + }
> > > pktopt = xchg(&np->pktoptions, NULL);
> > > kfree_skb(pktopt);
> >
> > Is here something special going on (because of the xchg). I don't see
> > why you cannot simply use a RCU_INIT_POINTER?
> >
> > Thanks,
> > Hannes
>
> Yes, I mentioned this earlier, and will be addressed in net-next tree
> later.
>
> (Same for np->pktoptions)
>
> The xchg() here does not bring additional protection as we are the last
> user of np.
>
> Thanks.

Ah, sorry, maybe I missed it. Just reviewed the patches after a longer
weekend here.

The rest looked fine to me:

Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>

Thanks!


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