linux-kernel - Re: [PATCH 1/2] events/core: introduce perf_pmu_disable

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Message-ID: <CAFgQCTvJXtWY21CUzOT5=_RYNF-r1kWm-uE10TbPCNcaaxH2SA@mail.gmail.com>
Date:   Tue, 24 Nov 2020 16:50:45 +0800
From:   Pingfan Liu <kernelfans@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, Omar Sandoval <osandov@...com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...nel.org>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>
Subject: Re: [PATCH 1/2] events/core: introduce perf_pmu_disable_all() to turn
 off all PMU

On Mon, Nov 23, 2020 at 10:05 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Mon, Nov 23, 2020 at 01:37:25PM +0800, Pingfan Liu wrote:
>
> > +/* When crashed, other cpus hang in idle loop, so here do an emergency job under no lock */
>
> -ENOPARSE, -ETOOLONG
>
> > +void perf_pmu_disable_all(void)
> > +{
> > +     struct pmu *pmu;
> > +
> > +     list_for_each_entry(pmu, &pmus, entry)
> > +             if (pmu->pmu_disable)
> > +                     pmu->pmu_disable(pmu);
> > +}
>
> This violates both locking rules and coding style.
Oops. I will re-work on it to see how to run it safely on crashed context.

Thanks,
Pingfan