netdev - Re: [PATCH bpf-next v3 03/16] xdp: add proper __rcu annotations to redirect map entries

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Message-ID: <87eecsonno.fsf@toke.dk>
Date:   Wed, 23 Jun 2021 12:55:55 +0200
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     paulmck@...nel.org
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Hangbin Liu <liuhangbin@...il.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Magnus Karlsson <magnus.karlsson@...il.com>,
        Jakub Kicinski <kuba@...nel.org>, bpf@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH bpf-next v3 03/16] xdp: add proper __rcu annotations to
 redirect map entries

"Paul E. McKenney" <paulmck@...nel.org> writes:

> On Tue, Jun 22, 2021 at 11:48:26PM +0200, Toke Høiland-Jørgensen wrote:
>> "Paul E. McKenney" <paulmck@...nel.org> writes:
>> 
>> > On Tue, Jun 22, 2021 at 03:55:25PM +0200, Toke Høiland-Jørgensen wrote:
>> >> Toke Høiland-Jørgensen <toke@...hat.com> writes:
>> >> 
>> >> >> It would also be great if this scenario in general could be placed
>> >> >> under the Documentation/RCU/whatisRCU.rst as an example, so we could
>> >> >> refer to the official doc on this, too, if Paul is good with this.
>> >> >
>> >> > I'll take a look and see if I can find a way to fit it in there...
>> >> 
>> >> OK, I poked around in Documentation/RCU and decided that the most
>> >> natural place to put this was in checklist.rst which already talks about
>> >> local_bh_disable(), but a bit differently. Fixing that up to correspond
>> >> to what we've been discussing in this thread, and adding a mention of
>> >> XDP as a usage example, results in the patch below.
>> >> 
>> >> Paul, WDYT?
>> >
>> > I think that my original paragraph needed to have been updated back
>> > when v4.20 came out.  And again when RCU Tasks Trace came out.  ;-)
>> >
>> > So I did that updating, then approximated your patch on top of it,
>> > as shown below.  Does this work for you?
>> 
>> Yup, LGTM, thanks! Shall I just fold that version into the next version
>> of my series, or do you want to take it through your tree (I suppose
>> it's independent of the rest, so either way is fine by me)?
>
> I currently have the two here in -rcu, most likely for v5.15 (as in
> the merge window after the upcoming one):
>
> 2b7cb9d95ba4 ("doc: Clarify and expand RCU updaters and corresponding readers")
> c6ef58907d22 ("doc: Give XDP as example of non-obvious RCU reader/updater pairing")
>
> I am happy taking it, but if you really would like to add it to your
> series, please do take both.  ;-)

Alright, I'll fold both in to v4 :)

-Toke