From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH v4 2/2] soc: qcom: add l2 cache perf events driver
Date: Fri, 2 Sep 2016 11:06:24 +0100
Message-ID: <20160902100624.GB9261@leverpostej>
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 <20160901163051.GA6731@leverpostej>
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To: Neil Leeder <nleeder@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, Arnaldo Carvalho de Melo <acme@kernel.org>, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Mark Langsdorf <mlangsdo@redhat.com>, Mark Salter <msalter@redhat.com>, Jon Masters <jcm@redhat.com>, Timur Tabi <timur@codeaurora.org>, cov@codeaurora.org
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On Thu, Sep 01, 2016 at 05:30:52PM +0100, Mark Rutland wrote:
> On Tue, Aug 30, 2016 at 01:01:33PM -0400, Neil Leeder wrote:
> > +static DEFINE_MUTEX(l2cache_pmu_mutex);
> 
> A mutex (which can sleep) is not safe for the hotplug state machine
> stuff. See recent patches to the arm_pmu code.
> 
> That's further subsumed by the multi-instance stuff, so this (and the
> list) will not be necessary shortly.

This has *just* landed in tip. See the smp/hotplug branch [1]. The
arm_pmu change [2] should serve as an example of what to do.

Thanks,
Mark.

[1] https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/log/?h=smp/hotplug
[2] https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/commit/?h=smp/hotplug&id=cc727977acb0fe05b7aa1f00cccb893530820895