On Tue, Oct 1, 2019 at 12:53 PM Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx> wrote: > > Hi Nick, > > On 25/09/2019 14:32:09-0600, Nick Crews wrote: > > If the RTC HW returns an invalid time, the rtc_year_days() > > call would crash. This patch adds error logging in this > > situation, and removes the tm_yday and tm_wday calculations. > > These fields should not be relied upon by userspace > > according to man rtc, and thus we don't need to calculate > > them. > > > > Signed-off-by: Nick Crews <ncrews@xxxxxxxxxxxx> > > --- > > drivers/rtc/rtc-wilco-ec.c | 13 +++++++++---- > > 1 file changed, 9 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/rtc/rtc-wilco-ec.c b/drivers/rtc/rtc-wilco-ec.c > > index 8ad4c4e6d557..53da355d996a 100644 > > --- a/drivers/rtc/rtc-wilco-ec.c > > +++ b/drivers/rtc/rtc-wilco-ec.c > > @@ -110,10 +110,15 @@ static int wilco_ec_rtc_read(struct device *dev, struct rtc_time *tm) > > tm->tm_mday = rtc.day; > > tm->tm_mon = rtc.month - 1; > > tm->tm_year = rtc.year + (rtc.century * 100) - 1900; > > - tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year); > > - > > - /* Don't compute day of week, we don't need it. */ > > - tm->tm_wday = -1; > > + /* Ignore other tm fields, man rtc says userspace shouldn't use them. */ > > + > > + if (rtc_valid_tm(tm)) { > > + dev_err(dev, > > + "Time from RTC is invalid: second=%u, minute=%u, hour=%u, day=%u, month=%u, year=%u, century=%u", > > + rtc.second, rtc.minute, rtc.hour, rtc.day, rtc.month, > > + rtc.year, rtc.century); > > Do you mind using %ptR? At this point you already filled the tm struct > anyway and if you print century separately, you can infer tm_year. I do not think this is a good idea: we have just established that tm does not contain valid data. Does %ptR guarantee that it handles junk better than, let's say, rtc_year_days(), and does not crash when presented with garbage? Thanks, Dmitry