From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Victor Ding <victording@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Alessandro Zummo <a.zummo@towertech.it>,
linux-rtc@vger.kernel.org
Subject: Re: [PATCH] rtc: cmos: initialize rtc time when reading alarm
Date: Thu, 13 Aug 2020 09:33:25 +0200 [thread overview]
Message-ID: <20200813073325.GK3480@piout.net> (raw)
In-Reply-To: <20200813154020.1.Iaf7638a2f2a87ff68d85fcb8dec615e41340c97f@changeid>
Hi,
On 13/08/2020 15:41:34+1000, Victor Ding wrote:
> cmos_read_alarm() may leave certain fields of a struct rtc_time
> untouched; therefore, these fields contain garbage if not properly
> initialized, leading to inconsistent values when converting into
> time64_t.
> This patch to set all fields of a struct rtc_time to -1 before calling
> cmos_read_alarm().
>
I don't think this actually helps with the conversion as mktime64
is taking unsigned int so I would think you need the whole logic that is
in __rtc_read_alarm
> Signed-off-by: Victor Ding <victording@google.com>
> ---
>
> drivers/rtc/rtc-cmos.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
> index bcc96ab7793f..c99af567780d 100644
> --- a/drivers/rtc/rtc-cmos.c
> +++ b/drivers/rtc/rtc-cmos.c
> @@ -1006,6 +1006,7 @@ static int cmos_suspend(struct device *dev)
> enable_irq_wake(cmos->irq);
> }
>
> + memset(&cmos->saved_wkalrm.time, -1, sizeof(struct rtc_time));
> cmos_read_alarm(dev, &cmos->saved_wkalrm);
>
> dev_dbg(dev, "suspend%s, ctrl %02x\n",
> @@ -1054,6 +1055,7 @@ static void cmos_check_wkalrm(struct device *dev)
> return;
> }
>
> + memset(¤t_alarm.time, -1, sizeof(struct rtc_time));
> cmos_read_alarm(dev, ¤t_alarm);
> t_current_expires = rtc_tm_to_time64(¤t_alarm.time);
> t_saved_expires = rtc_tm_to_time64(&cmos->saved_wkalrm.time);
> --
> 2.28.0.236.gb10cc79966-goog
>
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2020-08-13 7:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-13 5:41 [PATCH] rtc: cmos: initialize rtc time when reading alarm Victor Ding
2020-08-13 7:33 ` Alexandre Belloni [this message]
2020-08-14 6:10 ` Victor Ding
2020-08-14 8:15 ` Alexandre Belloni
2020-08-14 8:56 ` Victor Ding
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