[PATCH 5.5 100/367] alarmtimer: Unregister wakeup source when module get fails

[Greg Kroah-Hartman]

From: Stephen Boyd <swboyd@xxxxxxxxxxxx>

commit 6b6d188aae79a630957aefd88ff5c42af6553ee3 upstream.

The alarmtimer_rtc_add_device() function creates a wakeup source and then
tries to grab a module reference. If that fails the function returns early
with an error code, but fails to remove the wakeup source.

Cleanup this exit path so there is no dangling wakeup source, which is
named 'alarmtime' left allocated which will conflict with another RTC
device that may be registered later.

Fixes: 51218298a25e ("alarmtimer: Ensure RTC module is not unloaded")
Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20200109155910.907-2-swboyd@xxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 kernel/time/alarmtimer.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -88,6 +88,7 @@ static int alarmtimer_rtc_add_device(str
 	unsigned long flags;
 	struct rtc_device *rtc = to_rtc_device(dev);
 	struct wakeup_source *__ws;
+	int ret = 0;
 
 	if (rtcdev)
 		return -EBUSY;
@@ -102,8 +103,8 @@ static int alarmtimer_rtc_add_device(str
 	spin_lock_irqsave(&rtcdev_lock, flags);
 	if (!rtcdev) {
 		if (!try_module_get(rtc->owner)) {
-			spin_unlock_irqrestore(&rtcdev_lock, flags);
-			return -1;
+			ret = -1;
+			goto unlock;
 		}
 
 		rtcdev = rtc;
@@ -112,11 +113,12 @@ static int alarmtimer_rtc_add_device(str
 		ws = __ws;
 		__ws = NULL;
 	}
+unlock:
 	spin_unlock_irqrestore(&rtcdev_lock, flags);
 
 	wakeup_source_unregister(__ws);
 
-	return 0;
+	return ret;
 }
 
 static inline void alarmtimer_rtc_timer_init(void)