linux-kernel - Re: [PATCH] clk: exynos: use irqsave version of spin

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Message-ID: <CA+Ln22Fgn3JjbQ0MgMdsZk_4xsAy3Y6i2DEqm6WN2ORuJYZCPQ@mail.gmail.com>
Date:	Mon, 14 Dec 2015 20:02:54 +0900
From:	Tomasz Figa <tomasz.figa@...il.com>
To:	Marek Szyprowski <m.szyprowski@...sung.com>
Cc:	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Mike Turquette <mturquette@...libre.com>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Thomas Abraham <thomas.ab@...sung.com>,
	Ben Gamari <ben@...rt-cactus.org>,
	Lukasz Majewski <l.majewski@...sung.com>,
	Chanwoo Choi <cw00.choi@...sung.com>,
	Kevin Hilman <khilman@...aro.org>, stable@...r.kernel.org
Subject: Re: [PATCH] clk: exynos: use irqsave version of spin_lock to avoid
 deadlock with irqs

Hi Marek,

2015-12-11 23:38 GMT+09:00 Marek Szyprowski <m.szyprowski@...sung.com>:
> It is allowed to enable/disable clocks from interrupts, so common Exynos
> ARM clock management code for CPUfreq should use 'irqsave' version of
> spin_lock calls to avoid potential deadlock caused by spin_lock recursion.
> The same spin_lock is used by gate/mux clocks during enable/disable calls.
>
> This deadlock, can be reproduced by enabling CPUfreq (ondemand or
> userspace) and decoding video with s5p-mfc driver.

Good catch.

Acked-by: Tomasz Figa <tomasz.figa@...il.com>

Best regards,
Tomasz
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