Date: Thu, 1 Aug 2013 15:32:17 +0200
From: Jiri Olsa <jolsa@redhat.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>, LKML <linux-kernel@vger.kernel.org>,
        Namhyung Kim <namhyung@kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH 2/8] perf: Sanitize get_callchain_buffer()
Message-ID: <20130801133217.GH1032@krava.brq.redhat.com>
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 <20130801130146.GE1032@krava.brq.redhat.com>
 <20130801132833.GA431@somewhere>
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On Thu, Aug 01, 2013 at 03:28:34PM +0200, Frederic Weisbecker wrote:

SNIP

> > also for following case:
> > 
> >         count = atomic_inc_return(&nr_callchain_events);
> >         if (WARN_ON_ONCE(count < 1)) {
> >                 err = -EINVAL;
> >                 goto exit;
> >         }
> > 
> > seems like it screws the count
> 
> I'm not sure what you mean here. You mean that it could be negative when the dec is done
> outside the lock?

yes

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