linux-kernel - Re: [PATCH 01/13] perf: Simplify perf_event

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Message-ID: <CAM9d7chKHryDF45QUV+UtgZ+qiLsOsseXR5hXb=D8JS74HREDw@mail.gmail.com>
Date:   Wed, 15 Nov 2023 07:12:48 -0800
From:   Namhyung Kim <namhyung@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Jiri Olsa <olsajiri@...il.com>, mingo@...nel.org,
        linux-kernel@...r.kernel.org, acme@...nel.org,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        irogers@...gle.com, adrian.hunter@...el.com
Subject: Re: [PATCH 01/13] perf: Simplify perf_event_alloc() error path

On Wed, Nov 15, 2023 at 1:58 AM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Fri, Nov 03, 2023 at 12:50:19PM -0700, Namhyung Kim wrote:
>
> > > > -err_pmu:
> > > > -     if (is_cgroup_event(event))
> > > > -             perf_detach_cgroup(event);
> > > > -     if (event->destroy)
> > > > -             event->destroy(event);
> > > > -     module_put(pmu->module);
> >
> > I'm afraid of this part.  If it failed at perf_init_event(), it might
> > call event->destroy() already.  I saw you cleared event->pmu
> > in the failure path.  Maybe we need the same thing for the
> > event->destroy.
>
> In that case event->destroy will not yet have been set, no?

In perf_try_init_event(), it calls event->destroy() if set when it
has EXTENDED_REGS or NO_EXCLUDE capabilities and returns an error.

Thanks,
Namhyung