linux-kernel - [PATCH 1/4] alarmtimer: Unregister wakeup source when module get fails

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Message-Id: <20200109155910.907-2-swboyd@chromium.org>
Date:   Thu,  9 Jan 2020 07:59:07 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     John Stultz <john.stultz@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Douglas Anderson <dianders@...omium.org>,
        Ravi Chandra Sadineni <ravisadineni@...omium.org>,
        linux-kernel@...r.kernel.org, Stephen Boyd <sboyd@...nel.org>
Subject: [PATCH 1/4] alarmtimer: Unregister wakeup source when module get fails

The alarmtimer_rtc_add_device() function creates a wakeup source and
then tries to grab a module reference. If that fails we return early
with a -1, but forget to remove the wakeup source. Cleanup this exit
path so we don't leave a dangling wakeup source allocated and named
'alarmtimer' that will conflict with another RTC device that may be
registered.

Fixes: 51218298a25e ("alarmtimer: Ensure RTC module is not unloaded")
Signed-off-by: Stephen Boyd <swboyd@...omium.org>
---
 kernel/time/alarmtimer.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 451f9d05ccfe..4b11f0309eee 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -88,6 +88,7 @@ static int alarmtimer_rtc_add_device(struct device *dev,
 	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(struct device *dev,
 	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(struct device *dev,
 		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)
-- 
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