linux-kernel - Re: [PATCH RFC 0/2] rtc-cmos: Workaround unwanted interrupt generation

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Date:	Mon, 27 Jun 2016 10:19:07 +0530
From:	Pratyush Anand <panand@...hat.com>
To:	mingo@...nel.org, alexandre.belloni@...e-electrons.com,
	Thomas Gleixner <tglx@...utronix.de>
Cc:	rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org,
	prarit@...hat.com
Subject: Re: [PATCH RFC 0/2] rtc-cmos: Workaround unwanted interrupt
 generation

On 21/06/2016:10:25:34 AM, Pratyush Anand wrote:
> We have observed on few machines with rtc-cmos device that
> hpet_rtc_interrupt() is called before cmos_do_probe() could call
> hpet_rtc_timer_init(). It has not been observed during normal boot/reboot
> of machines. It *sometime* happens when system is booted with kdump
> secondary kernel. So, neither hpet_default_delta nor hpet_t1_cmp is
> initialized by the time interrupt is raised in the given situation.
> Therefore while loop of hpet_cnt_ahead() in hpet_rtc_timer_reinit() never
> completes. This leads to "NMI watchdog: Watchdog detected hard LOCKUP on
> cpu 0".
> 
> I am still clueless, how can an interrupt be raised before RTC is enabled.
> But i do not have any idea about this device, so I am putting this patch as
> RFC to get feedback from hpet/rtc-cmos developer. I am sure there would be
> some better solution than this.

Do you think that if I improve commit log of patches as pointed by Thomas and
send a formal version of these patches, then they should acceptable to upstream?

Thanks

~Pratyush
> 
> 
> 
> Pratyush Anand (2):
>   rtc/hpet: Factorize hpet_rtc_timer_init()
>   rtc/rtc-cmos: Initialize software counters before irq is registered
> 
>  arch/x86/include/asm/hpet.h |  2 ++
>  arch/x86/kernel/hpet.c      | 41 +++++++++++++++++++++++++++++++++++------
>  drivers/rtc/rtc-cmos.c      | 13 ++++++++++++-
>  3 files changed, 49 insertions(+), 7 deletions(-)
> 
> -- 
> 2.5.5