linux-kernel - Re: [PATCH] rtc: check if __rtc_read_time was successful in rtc_timer_do

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Message-ID: <20241129232038ad3be3ae@mail.local>
Date: Sat, 30 Nov 2024 00:20:38 +0100
From: Alexandre Belloni <alexandre.belloni@...tlin.com>
To: 高永良 <leonylgao@...il.com>
Cc: john.stultz@...aro.org, linux-rtc@...r.kernel.org,
	linux-kernel@...r.kernel.org, Yongliang Gao <leonylgao@...cent.com>,
	Jingqun Li <jingqunli@...cent.com>
Subject: Re: [PATCH] rtc: check if __rtc_read_time was successful in
 rtc_timer_do_work()

On 20/11/2024 22:17:34+0800, 高永良 wrote:
> Hi Alexandre Belloni,
> 
> I've noticed that the post-failure process for __rtc_read_time requires
> careful handling.
> 1. Need to call pm_relax.

I had a look when taking your patch and I'm not convinced calling
pm_relax is necessary.

> 2. Potentially need to set the alarm to ensure subsequent interrupts can
> process the
>     expired timer? Could you give me some advice?

Same thing, if you are not able to read the current time, setting the
next alarm is going to fail anyway.

> Should I continue to submit a fix patch or create a v2 version of the patch?
> 
> Best Regards,
> Yongliang Gao
> 
> Alexandre Belloni <alexandre.belloni@...tlin.com> 于2024年11月12日周二 06:11写道：
> 
> > On Fri, 11 Oct 2024 12:31:53 +0800, Yongliang Gao wrote:
> > > If the __rtc_read_time call fails,, the struct rtc_time tm; may contain
> > > uninitialized data, or an illegal date/time read from the RTC hardware.
> > >
> > > When calling rtc_tm_to_ktime later, the result may be a very large value
> > > (possibly KTIME_MAX). If there are periodic timers in rtc->timerqueue,
> > > they will continually expire, may causing kernel softlockup.
> > >
> > > [...]
> >
> > Applied, thanks!
> >
> > [1/1] rtc: check if __rtc_read_time was successful in rtc_timer_do_work()
> >       https://git.kernel.org/abelloni/c/e8ba8a2bc4f6
> >
> > Best regards,
> >
> > --
> > Alexandre Belloni, co-owner and COO, Bootlin
> > Embedded Linux and Kernel engineering
> > https://bootlin.com
> >

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com