From: Maxime Ripard <maxime.ripard@free-electrons.com>
To: Chen-Yu Tsai <wens@csie.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH v3] clocksource: sun4i: Clear interrupts after stopping timer in probe function
Date: Thu, 25 Aug 2016 10:04:09 +0200 [thread overview]
Message-ID: <20160825080409.GE7776@lukather> (raw)
In-Reply-To: <20160825062659.17433-1-wens@csie.org>
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On Thu, Aug 25, 2016 at 02:26:59PM +0800, Chen-Yu Tsai wrote:
> The bootloader (U-boot) sometimes uses this timer for various delays.
> It uses it as a ongoing counter, and does comparisons on the current
> counter value. The timer counter is never stopped.
>
> In some cases when the user interacts with the bootloader, or lets
> it idle for some time before loading Linux, the timer may expire,
> and an interrupt will be pending. This results in an unexpected
> interrupt when the timer interrupt is enabled by the kernel, at
> which point the event_handler isn't set yet. This results in a NULL
> pointer dereference exception, panic, and no way to reboot.
>
> Clear any pending interrupts after we stop the timer in the probe
> function to avoid this.
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Thanks!
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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next prev parent reply other threads:[~2016-08-25 8:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-25 6:26 [PATCH v3] clocksource: sun4i: Clear interrupts after stopping timer in probe function Chen-Yu Tsai
2016-08-25 8:04 ` Maxime Ripard [this message]
2016-08-25 9:11 ` Daniel Lezcano
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