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SubjectRe: [PATCH 2/3] jump_labels: do not use unserialized static_key_enabled


----- Original Message -----
> From: "Eric Dumazet" <eric.dumazet@gmail.com>
> To: "Paolo Bonzini" <pbonzini@redhat.com>
> Cc: linux-kernel@vger.kernel.org, "Peter Zijlstra" <peterz@infradead.org>
> Sent: Tuesday, August 1, 2017 10:52:14 PM
> Subject: Re: [PATCH 2/3] jump_labels: do not use unserialized static_key_enabled
>
> On Tue, 2017-08-01 at 17:24 +0200, Paolo Bonzini wrote:
> > Any use of key->enabled (that is static_key_enabled and static_key_count)
> > outside jump_label_lock should handle its own serialization. The only
> > two that are not doing so are the UDP encapsulation static keys. Change
> > them to use static_key_enable, which now correctly tests key->enabled under
> > the jump label lock.
> >
> > diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> > index 1d6219bf2d6b..74b7810df9fc 100644
> > --- a/net/ipv4/udp.c
> > +++ b/net/ipv4/udp.c
> > @@ -1644,8 +1644,7 @@ static int __udp_queue_rcv_skb(struct sock *sk,
> > struct sk_buff *skb)
> > static struct static_key udp_encap_needed __read_mostly;
> > void udp_encap_enable(void)
> > {
> > - if (!static_key_enabled(&udp_encap_needed))
> > - static_key_slow_inc(&udp_encap_needed);
> > + static_key_enable(&udp_encap_needed);
> > }
>
> Looks good to me, but static_key_enable() is not serialized either ?
>
> I suspect you should have CCed me on patch 1/3 :)

Yes, indeed... That's the "now correctly test" in the commit message.
What a difference one word makes. :)

You can find 1/3 at https://patchwork.kernel.org/patch/9874845/.

Paolo

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