linux-kernel - Re: [PATCH] perf/aux: Properly launch pending disable flow

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Message-ID: <20250624133217.GO794930@e132581.arm.com>
Date: Tue, 24 Jun 2025 14:32:17 +0100
From: Leo Yan <leo.yan@....com>
To: James Clark <james.clark@...aro.org>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	Marco Elver <elver@...gle.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf/aux: Properly launch pending disable flow

On Tue, Jun 24, 2025 at 02:11:38PM +0100, James Clark wrote:

[...]

> > @@ -441,7 +441,7 @@ void *perf_aux_output_begin(struct perf_output_handle *handle,
> >   		 * store that will be enabled on successful return
> >   		 */
> >   		if (!handle->size) { /* A, matches D */
> > -			event->pending_disable = smp_processor_id();
> > +			perf_event_disable_inatomic(handle->event);
> >   			perf_output_wakeup(handle);
> >   			WRITE_ONCE(rb->aux_nest, 0);
> >   			goto err_put;
> > @@ -526,7 +526,7 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size)
> >   	if (wakeup) {
> >   		if (handle->aux_flags & PERF_AUX_FLAG_TRUNCATED)
> > -			handle->event->pending_disable = smp_processor_id();
> > +			perf_event_disable_inatomic(handle->event);
> >   		perf_output_wakeup(handle);
> >   	}
> 
> The types are now a bit misleading and pending_wakeup and pending_disable
> could be bool types. The other pending_*s do use their types properly
> though.
> 
> __perf_pending_disable() also still contains a big comment that describes
> use of CPU ID and -1 values.

I might use an extra patch to address type and comment issue.

> Other than that it makes sense.
> 
> Reviewed-by: James Clark <james.clark@...aro.org>

Thanks for review!