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

On Tue, Jun 22, 2021 at 11:48:26PM +0200, Toke Høiland-Jørgensen wrote:

"Paul E. McKenney" [off-list ref] writes:

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On Tue, Jun 22, 2021 at 03:55:25PM +0200, Toke Høiland-Jørgensen wrote:

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Toke Høiland-Jørgensen [off-list ref] writes:

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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.  ;-)

							Thanx, Paul