Hi,
2021年8月31日(火) 2:26 Mateusz Jończyk <mat.jonczyk@xxxxx>:
>
> Reading from the CMOS involves writing to the index register and then
> reading from the data register. Therefore access to the CMOS has to be
> serialized with a spinlock. An invocation in cmos_set_alarm was not
> serialized with rtc_lock, fix this.
>
> Use spin_lock_irq() like the rest of the function.
>
> Nothing in kernel modifies the RTC_DM_BINARY bit, so use a separate pair
> of spin_lock_irq() / spin_unlock_irq() before doing the math.
>
> Signed-off-by: Mateusz Jończyk <mat.jonczyk@xxxxx>
> Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
> Cc: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> drivers/rtc/rtc-cmos.c | 3 +++
> 1 file changed, 3 insertions(+)
Reviewed-by: Nobuhiro Iwamatsu <iwamatsu@xxxxxxxxxxx>
Best regards,
Nobuhiro
>
> diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
> index 0fa66d1039b9..e6ff0fb7591b 100644
> --- a/drivers/rtc/rtc-cmos.c
> +++ b/drivers/rtc/rtc-cmos.c
> @@ -463,7 +463,10 @@ static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
> min = t->time.tm_min;
> sec = t->time.tm_sec;
>
> + spin_lock_irq(&rtc_lock);
> rtc_control = CMOS_READ(RTC_CONTROL);
> + spin_unlock_irq(&rtc_lock);
> +
> if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
> /* Writing 0xff means "don't care" or "match all". */
> mon = (mon <= 12) ? bin2bcd(mon) : 0xff;
> --
> 2.25.1
>
--
Nobuhiro Iwamatsu
iwamatsu at {nigauri.org / debian.org}
GPG ID: 40AD1FA6
