linux-kernel - Re: [PATCH 1/3] perf/x86/intel/bts: Fix confused ordering of PMU callbacks

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Date:   Wed, 24 Aug 2016 15:28:22 +0300
From:   Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:     Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        vince@...ter.net, eranian@...gle.com,
        Arnaldo Carvalho de Melo <acme@...radead.org>
Subject: Re: [PATCH 1/3] perf/x86/intel/bts: Fix confused ordering of PMU callbacks

Alexander Shishkin <alexander.shishkin@...ux.intel.com> writes:

> The intel_bts driver is using a cpu-local 'started' variable to order
> callbacks and PMIs and make sure that AUX transactions don't get messed
> up. However, the ordering rules in regard to this variable is a complete
> mess, which recently resulted in perf_fuzzer-triggered warnings and
> panics.
>
> The general ordering rule that is patch is enforcing is that this
> cpu-local variable be set only when the cpu-local AUX transaction is
> active; consequently, this variable is to be checked before the AUX
> related bits can be touched.
>
> Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>

Ok, this one is broken, please disregard.

Regards,
--
Alex