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

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Message-ID: <CAJxhyqB4CfLBwfgcDQFm7KZBwom58SPJvTSXdUTo+9saW46+zQ@mail.gmail.com>
Date: Wed, 20 Nov 2024 22:32:21 +0800
From: Yongliang Gao <leonylgao@...il.com>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: 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()

Hi Alexandre Belloni,

I've noticed that the post-failure process for __rtc_read_time
requires careful handling.
1. Need to call pm_relax.
2. Potentially need to set the alarm to ensure subsequent interrupts
can process the
    expired timer? Could you give me some advice?
Should I continue to submit a fix patch or create a v2 version of the patch?

Best Regards,
Yongliang Gao

On Tue, Nov 12, 2024 at 6:11 AM Alexandre Belloni
<alexandre.belloni@...tlin.com> wrote:
>
> 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