From: Alexandre Belloni <alexandre.belloni@bootlin.com>
Date: Tue, 5 Jun 2018 21:09:14 +0000 (+0200)
Subject: rtc: ensure rtc_set_alarm fails when alarms are not supported
X-Git-Tag: v4.9.117~124
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=fda8caa9cb0c80deab362d73a8fd2cd322ce20fc;p=platform%2Fkernel%2Flinux-amlogic.git

rtc: ensure rtc_set_alarm fails when alarms are not supported

[ Upstream commit abfdff44bc38e9e2ef7929f633fb8462632299d4 ]

When using RTC_ALM_SET or RTC_WKALM_SET with rtc_wkalrm.enabled not set,
rtc_timer_enqueue() is not called and rtc_set_alarm() may succeed but the
subsequent RTC_AIE_ON ioctl will fail. RTC_ALM_READ would also fail in that
case.

Ensure rtc_set_alarm() fails when alarms are not supported to avoid letting
programs think the alarms are working for a particular RTC when they are
not.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 25cf3069e2e7..4131bfb2cc61 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -359,6 +359,11 @@ int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 {
 	int err;
 
+	if (!rtc->ops)
+		return -ENODEV;
+	else if (!rtc->ops->set_alarm)
+		return -EINVAL;
+
 	err = rtc_valid_tm(&alarm->time);
 	if (err != 0)
 		return err;