[PATCH] RTC: Fix infinite loop in initializing the alarm.

[PATCH] RTC: Fix infinite loop in initializing the alarm.

[Ales Novak]

In __rtc_read_alarm(), if the alarm time retrieved by
rtc_read_alarm_internal() from the device contains invalid values
(e.g. month=2,mday=31) and the year not set (=-1), the initialization
will loop infinitely because the year-fixing loop expects the
time being invalid due to leap year.

Fix reduces the loop to the leap years and adds final validity check.

Signed-off-by: Ales Novak <alnovak@suse.cz>
---
 drivers/rtc/interface.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 544be72..a2df283 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -292,7 +292,9 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 		dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 		do {
 			alarm->time.tm_year++;
-		} while (rtc_valid_tm(&alarm->time) != 0);
+		} while (alarm->time.tm_mon == 1
+			&& is_leap_year(alarm->time.tm_year + 1900)
+			&& rtc_valid_tm(&alarm->time) != 0);
 		break;
 
 	default:
@@ -300,7 +302,16 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 	}
 
 done:
-	return 0;
+	err = rtc_valid_tm(&alarm->time);
+
+	if (err) {
+		dev_warn(&rtc->dev, "invalid alarm value: %d-%d-%d %d:%d:%d\n",
+			alarm->time.tm_year + 1900, alarm->time.tm_mon + 1,
+			alarm->time.tm_mday, alarm->time.tm_hour, alarm->time.tm_min,
+			alarm->time.tm_sec);
+	}
+
+	return err;
 }
 
 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
-- 
1.8.1.4

Re: [PATCH] RTC: Fix infinite loop in initializing the alarm.

[Alessandro Zummo]

On Tue,  8 Apr 2014 00:54:42 +0200
Ales Novak <alnovak@suse.cz> wrote:

> In __rtc_read_alarm(), if the alarm time retrieved by
> rtc_read_alarm_internal() from the device contains invalid values
> (e.g. month=2,mday=31) and the year not set (=-1), the initialization
> will loop infinitely because the year-fixing loop expects the
> time being invalid due to leap year.
> 
> Fix reduces the loop to the leap years and adds final validity check.
> 
> Signed-off-by: Ales Novak <alnovak@suse.cz>

 Seems reasonable.

 Acked-by: Alessandro Zummo <a.zummo@towertech.it>

-- 

 Best regards,

 Alessandro Zummo,
  Tower Technologies - Torino, Italy

  http://www.towertech.it

[PATCH] drivers/rtc/interface.c: fix for fix of alarm initialization

[Ales Novak]

Seems the previous patch "fix infinite loop in initializing the alarm"
did break the infinite loop in alarm initialization, but not in the right
way. The loop indeed should walk through the not-leap years and stop on
the leap one.

This patch does apply on top of the previous one.

Signed-off-by: Ales Novak <alnovak@suse.cz>
---
Fix for patch drivers-rtc-interfacec-fix-infinite-loop-in-initializing-the-alarm

 drivers/rtc/interface.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index a2df283..bd6314a 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -292,8 +292,7 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 		dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 		do {
 			alarm->time.tm_year++;
-		} while (alarm->time.tm_mon == 1
-			&& is_leap_year(alarm->time.tm_year + 1900)
+		} while (!is_leap_year(alarm->time.tm_year + 1900)
 			&& rtc_valid_tm(&alarm->time) != 0);
 		break;
 
-- 
1.8.1.4