linux-kernel - RE: [PATCH 1/3] perf: convert perf_event_context.refcount to refcount

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Message-ID: <2236FBA76BA1254E88B949DDB74E612BA4B98D3A@IRSMSX102.ger.corp.intel.com>
Date:   Tue, 29 Jan 2019 13:55:32 +0000
From:   "Reshetova, Elena" <elena.reshetova@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "acme@...nel.org" <acme@...nel.org>,
        "namhyung@...nel.org" <namhyung@...nel.org>,
        "alexander.shishkin@...ux.intel.com" 
        <alexander.shishkin@...ux.intel.com>,
        "jolsa@...hat.com" <jolsa@...hat.com>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>
Subject: RE: [PATCH 1/3] perf: convert perf_event_context.refcount to
 refcount_t

> On Mon, Jan 28, 2019 at 02:27:26PM +0200, Elena Reshetova wrote:
> > diff --git a/kernel/events/core.c b/kernel/events/core.c
> > index 3cd13a3..a1e87d2 100644
> > --- a/kernel/events/core.c
> > +++ b/kernel/events/core.c
> > @@ -1171,7 +1171,7 @@ static void perf_event_ctx_deactivate(struct
> perf_event_context *ctx)
> >
> >  static void get_ctx(struct perf_event_context *ctx)
> >  {
> > -	WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
> > +	WARN_ON(!refcount_inc_not_zero(&ctx->refcount));
> 
> This could be refcount_inc(), remember how that already produces a WARN
> when we try and increment 0.

But is this true for the x86 arch-specific implementation also?