linux-kernel - Re: [PATCH] clockevents/drivers/cs5535: improve resilience to spurious interrupts

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Message-ID: <alpine.DEB.2.20.1710200023080.2054@nanos>
Date:   Fri, 20 Oct 2017 00:25:09 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
cc:     David Kozub <zub@...ux.fjfi.cvut.cz>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clockevents/drivers/cs5535: improve resilience to spurious
 interrupts

On Fri, 20 Oct 2017, Daniel Lezcano wrote:

> On 19/10/2017 22:57, David Kozub wrote:
> > This solves a BUG on ALIX 2c3 where mfgpt_tick is called before
> > clockevents_config_and_register returns. This caused mfgpt_tick to call a
> > null function pointer.
> > 
> > Thanks to Daniel Lezcano and Thomas Gleixner for helping me analyze this
> > and suggesting a solution.
> > 
> > Suggested-by: Thomas Gleixner <tglx@...utronix.de>
> > Signed-off-by: David Kozub <zub@...ux.fjfi.cvut.cz>
> > ---
> 
> Thank for sending this fix.
> 
> Can you check if the commit 8f9327cbb is the one introducing the
> regression ? So we can add the proper tags and propagate the fix to stable.

No it's not.

-       if (cs5535_tick_mode == CLOCK_EVT_MODE_SHUTDOWN)
+       if (clockevent_state_shutdown(&cs5535_clockevent))

This particular problem of the missing detached state check has been there
forever and went unnoticed for whatever reason.

Thanks,

	tglx