Re: [PATCH RFC v3 03/13] rcu-tasks: Add a Tasks RCU implementation for reader-marked trampolines

On Thu, Sep 17, 2026 at 12:25:40PM -0700, Paul E. McKenney wrote:

On Thu, Sep 17, 2026 at 08:45:36PM +0200, Frederic Weisbecker wrote:

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Le Thu, Sep 17, 2026 at 08:40:10AM -0700, Paul E. McKenney a écrit :

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Trampolines that transfer control to tracing code could supply the needed
cleanup call.  But last I checked, there were trampolines that transferred
directly back to the original code, with no opportunity for cleaning up.

Or am I still missing a trick here?

You're right. So we'll indeed need to reuse the deferred qs points here.

Except this is getting a bit involved.

Don't get me wrong, if Josef is happy to take this on, far be it from me
to stand in his way.  But if not, we should be willing to treat this
optimization as a follow-on effort, whether by Josef or someone else.

Sure, I guess I can try the follow-on, especially if it leads to removing
all this RCU tasks black magic.

That sounds most excellent, thank you!

Ah, and in case anyone (especially Josef) is wondering, one big advantage
of the more elaborate approach is that it allowed the real-time guys to
avoid yet another source of IPIs messing with their latencies.

							Thanx, Paul