Messages in this thread | | | Date | Wed, 23 Jul 2014 14:56:34 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] driver/rtc/class.c: check the error after rtc_read_time() |
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On Tue, 15 Jul 2014 17:25:23 +0900 Hyogi Gim <hyogi.gim@lge.com> wrote:
> In rtc_suspend() and rtc_resume(), the error after rtc_read_time() is not > checked. If rtc device fail to read time, we cannot guarantee the following > process. > > Add the verification code for returned rtc_read_time() error. > > ... > > --- a/drivers/rtc/class.c > +++ b/drivers/rtc/class.c > @@ -53,6 +53,7 @@ static int rtc_suspend(struct device *dev) > struct rtc_device *rtc = to_rtc_device(dev); > struct rtc_time tm; > struct timespec delta, delta_delta; > + int err; > > if (has_persistent_clock()) > return 0; > @@ -61,7 +62,12 @@ static int rtc_suspend(struct device *dev) > return 0; > > /* snapshot the current RTC and system time at suspend*/ > - rtc_read_time(rtc, &tm); > + err = rtc_read_time(rtc, &tm); > + if (err < 0) { > + pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev)); > + return 0; > + }
OK, it makes no sense to go ahead and set the system time from a garbage rtc_time.
But I'm wondering if we should propagate the error back to the rtc_suspend() caller. What does the PM core do if a particular device's ->suspend or ->resume fails?
> getnstimeofday(&old_system); > rtc_tm_to_time(&tm, &old_rtc.tv_sec); > > @@ -94,6 +100,7 @@ static int rtc_resume(struct device *dev) > struct rtc_time tm; > struct timespec new_system, new_rtc; > struct timespec sleep_time; > + int err; > > if (has_persistent_clock()) > return 0; > @@ -104,7 +111,12 @@ static int rtc_resume(struct device *dev) > > /* snapshot the current rtc and system time at resume */ > getnstimeofday(&new_system); > - rtc_read_time(rtc, &tm); > + err = rtc_read_time(rtc, &tm); > + if (err < 0) { > + pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev)); > + return 0; > + } > + > if (rtc_valid_tm(&tm) != 0) { > pr_debug("%s: bogus resume time\n", dev_name(&rtc->dev)); > return 0;
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