linux-kernel - Re: [PATCH] rtc/rtc-cmos: Initialize hpet timer before irq is registered

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Message-ID: <20160919222319.qvakrltsv52gu2hc@piout.net>
Date:   Tue, 20 Sep 2016 00:23:19 +0200
From:   Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:     Pratyush Anand <panand@...hat.com>
Cc:     mingo@...nel.org, tglx@...utronix.de, hpa@...or.com,
        x86@...nel.org, rtc-linux@...glegroups.com,
        linux-kernel@...r.kernel.org, prarit@...hat.com,
        dzickus@...hat.com, dyoung@...hat.com, a.zummo@...ertech.it
Subject: Re: [PATCH] rtc/rtc-cmos: Initialize hpet timer before irq is
 registered

On 15/09/2016 at 09:38:16 +0530, Pratyush Anand wrote :
> We have observed on few x86 machines with rtc-cmos device that
> hpet_rtc_interrupt() is called just after irq registration and before
> cmos_do_probe() could call hpet_rtc_timer_init().
> 
> So, neither hpet_default_delta nor hpet_t1_cmp is initialized by the time
> interrupt is raised in the given situation, and this results in NMI
> watchdog LOCKUP.
> 
> It has only been observed sporadically on kdump secondary kernels.
> 
[...]
> 
> Suggested-by: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Pratyush Anand <panand@...hat.com>
> ---
>  drivers/rtc/rtc-cmos.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
Applied, thanks.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com