linux-kernel - Re: [PATCH 01/10] perf/x86: Add warning on proper cpu during event's update

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Message-ID: <20170828192432.yufnjgylcayxvczs@hirez.programming.kicks-ass.net>
Date:   Mon, 28 Aug 2017 21:24:32 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        David Ahern <dsahern@...il.com>,
        Andi Kleen <andi@...stfloor.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH 01/10] perf/x86: Add warning on proper cpu during event's
 update

On Thu, Aug 24, 2017 at 06:27:28PM +0200, Jiri Olsa wrote:
> Mark reported that we could actually call pmu->read on
> unscheduled event. I think it's good idea to keep a
> warning here to see if we've get it wrong again in
> future.
> 
> Reported-by: Mark Rutland <mark.rutland@....com>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>

Yeah, no objection to this one.

Ack

> ---
>  arch/x86/events/core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
> index af12e294caed..b8e394d9f7f2 100644
> --- a/arch/x86/events/core.c
> +++ b/arch/x86/events/core.c
> @@ -72,6 +72,8 @@ u64 x86_perf_event_update(struct perf_event *event)
>  	int idx = hwc->idx;
>  	u64 delta;
>  
> +	WARN_ON_ONCE(event->oncpu != smp_processor_id());
> +
>  	if (idx == INTEL_PMC_IDX_FIXED_BTS)
>  		return 0;
>  
> -- 
> 2.9.5
>