Re: [PATCH] clocksource: sun4i: Clear interrupts after stopping timer in probe function

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH] clocksource: sun4i: Clear interrupts after stopping timer in probe function
Date	2016-07-26 11:20 +0200
Message-ID	<rZ6GS-8I-21@gated-at.bofh.it> (permalink)
References	<rZ0UO-53b-23@gated-at.bofh.it> <rZ3pD-6vo-1@gated-at.bofh.it> <rZ4lI-744-9@gated-at.bofh.it>
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On Tue, 26 Jul 2016, Chen-Yu Tsai wrote:
> On Tue, Jul 26, 2016 at 1:49 PM, Maxime Ripard
> <maxime.ripard@free-electrons.com> wrote:
> > On Tue, Jul 26, 2016 at 11:01:59AM +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.
> >>
> >> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> >
> > Awesome, thanks!
> >
> > You should put stable in Cc though for this kind of patches.
> 
> AFAIK some maintainers prefer to add it themselves. Not sure about
> clocksource so I left it out.

At least you should tell the maintainer, that you consider this to be stable
material. It's not an obvious stable candidate.

Thanks,

	tglx

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[PATCH] clocksource: sun4i: Clear interrupts after stopping timer in probe function Chen-Yu Tsai <wens@csie.org> - 2016-07-26 05:10 +0200
  Re: [PATCH] clocksource: sun4i: Clear interrupts after stopping  timer in probe function Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-07-26 07:50 +0200
    Re: [PATCH] clocksource: sun4i: Clear interrupts after stopping timer  in probe function Chen-Yu Tsai <wens@csie.org> - 2016-07-26 08:50 +0200
      Re: [PATCH] clocksource: sun4i: Clear interrupts after stopping  timer in probe function Thomas Gleixner <tglx@linutronix.de> - 2016-07-26 11:20 +0200

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