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SubjectRe: [PATCH] drivers/rtc/interface.c: check the error after __rtc_read_time()
On Wed, Dec 17, 2014 at 01:51:50PM -0800, Andrew Morton wrote:
> On Wed, 17 Dec 2014 12:15:24 +0900 Hyogi Gim <hyogi.gim@lge.com> wrote:
>
> > Add the verification code for returned __rtc_read_time() error in
> > rtc_update_irq_enable() and rtc_timer_do_work().
> >
> > ...
> L
> > --- a/drivers/rtc/interface.c
> > +++ b/drivers/rtc/interface.c
> > @@ -489,7 +489,10 @@ int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
> > struct rtc_time tm;
> > ktime_t now, onesec;
> >
> > - __rtc_read_time(rtc, &tm);
> > + err = __rtc_read_time(rtc, &tm);
> > + if (err < 0)
> > + goto out;
> > +
> > onesec = ktime_set(1, 0);
> > now = rtc_tm_to_ktime(tm);
> > rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
>
> I'm not sure about this part. If __rtc_read_time() returns -EINVAL
> (due to !rtc->ops->read_time) then rtc_update_irq_enable() will go and
> call rtc_dev_update_irq_enable_emul(), inappropriately.
>
> On the other hand, if __rtc_read_time() returns -EINVAL because that's
> what rtc->ops->read_time() returned then perhaps
> rtc_update_irq_enable() *should* call rtc_dev_update_irq_enable_emul().
>
> Messy.
>

As you said, if rtc driver has no read_time callback, rtc_read_time()
is failed in rtc_dev_update_irq_enable_emul() anyway.

rtc_dev_update_irq_enable_emul()
|_ set_uie()
|_ rtc_read_time()

What I worried about the error from rtc->ops->read_time().
If rtc->ops->read_time() returns another type of error except -EINVAL,
then rtc interface can't run rtc_dev_update_irq_enable_emul().

I think it needs to be changed that check to ensure error for
rtc_dev_update_irq_enable_emul().



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