linux-kernel - [PATCH] alarmtimer: check RTC features instead of ops

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Date:   Thu, 29 Apr 2021 23:49:02 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     John Stultz <john.stultz@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Stephen Boyd <sboyd@...nel.org>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] alarmtimer: check RTC features instead of ops

Test RTC_FEATURE_ALARM instead of relying on ops->set_alarm to know whether
alarms are available.

Fixes: 7ae41220ef58 ("rtc: introduce features bitfield")
Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
---
Hello,

This doesn't seem much but this solve an issue where following a change in the
RTC driver, this part of the code will think the RTC is alarm capable while it
is not, then breaking the alarmtimer functionnality.

 kernel/time/alarmtimer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 98d7a15e8cf6..4d7a6dffa1e5 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -92,7 +92,7 @@ static int alarmtimer_rtc_add_device(struct device *dev,
 	if (rtcdev)
 		return -EBUSY;
 
-	if (!rtc->ops->set_alarm)
+	if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
 		return -1;
 	if (!device_may_wakeup(rtc->dev.parent))
 		return -1;
-- 
2.30.2