Re: [PATCH] clocksource:fix kernel panic due missing event_handler in cs5535

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH] clocksource:fix kernel panic due missing event_handler in cs5535
Date	2016-05-30 12:40 +0200
Message-ID	<rEsM2-2Wp-25@gated-at.bofh.it> (permalink)
References	<rEsM2-2Wp-27@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Mon, 30 May 2016, Hans Ulli Kroll wrote:

> Missing event_handler in mfgpt_tick() caused a kernel panic.

So the real problem is that the interrupt in the device is enabled _BEFORE_
the clock event device is registered.
 
> diff --git a/drivers/clocksource/cs5535-clockevt.c b/drivers/clocksource/cs5535-clockevt.c
> index 9a7e37c..6f186cf 100644
> --- a/drivers/clocksource/cs5535-clockevt.c
> +++ b/drivers/clocksource/cs5535-clockevt.c
> @@ -129,7 +129,9 @@ static irqreturn_t mfgpt_tick(int irq, void *dev_id)
>  		cs5535_mfgpt_write(cs5535_event_clock, MFGPT_REG_SETUP,
>  				MFGPT_SETUP_CNTEN | MFGPT_SETUP_CMP2);
>  
> -	cs5535_clockevent.event_handler(&cs5535_clockevent);
> +	if (cs5535_clockevent.event_handler)
> +		cs5535_clockevent.event_handler(&cs5535_clockevent);
> +

So what about fixing the above problem instead of having a conditional in the
interrupt handler fast path?

Thanks,

	tglx

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Re: [PATCH] clocksource:fix kernel panic due missing event_handler  in cs5535 Thomas Gleixner <tglx@linutronix.de> - 2016-05-30 12:40 +0200
  Re: [PATCH] clocksource:fix kernel panic due missing event_handler  in cs5535 Hans Ulli Kroll <ulli.kroll@googlemail.com> - 2016-05-31 09:10 +0200

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