alarmtimer: Fix unavailable wake-up source in sysfs

Currently the alarmtimer registers a wake-up source unconditionally,
regardless of the system having a (wake-up capable) RTC or not.
Hence the alarmtimer will always show up in
/sys/kernel/debug/wakeup_sources, even if it is not available, and thus
cannot be a wake-up source.

To fix this, postpone registration until a wake-up capable RTC device is
added.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Stephen Boyd <stephen.boyd@linaro.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: John Stultz <john.stultz@linaro.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 0b8ff7d257ea..73a2b476e59f 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -56,9 +56,9 @@ static ktime_t freezer_delta;
 static DEFINE_SPINLOCK(freezer_delta_lock);
 #endif
 
+#ifdef CONFIG_RTC_CLASS
 static struct wakeup_source *ws;
 
-#ifdef CONFIG_RTC_CLASS
 /* rtc timer and device for setting alarm wakeups at suspend */
 static struct rtc_timer         rtctimer;
 static struct rtc_device        *rtcdev;
@@ -89,6 +89,7 @@ static int alarmtimer_rtc_add_device(struct device *dev,
 {
         unsigned long flags;
         struct rtc_device *rtc = to_rtc_device(dev);
+        struct wakeup_source *__ws;
 
         if (rtcdev)
                 return -EBUSY;
@@ -98,13 +99,20 @@ static int alarmtimer_rtc_add_device(struct device *dev,
         if (!device_may_wakeup(rtc->dev.parent))
                 return -1;
 
+        __ws = wakeup_source_register("alarmtimer");
+
         spin_lock_irqsave(&rtcdev_lock, flags);
         if (!rtcdev) {
                 rtcdev = rtc;
                 /* hold a reference so it doesn't go away */
                 get_device(dev);
+                ws = __ws;
+                __ws = NULL;
         }
         spin_unlock_irqrestore(&rtcdev_lock, flags);
+
+        wakeup_source_unregister(__ws);
+
         return 0;
 }
 
@@ -860,7 +868,6 @@ static int __init alarmtimer_init(void)
                 error = PTR_ERR(pdev);
                 goto out_drv;
         }
-        ws = wakeup_source_register("alarmtimer");
         return 0;
 
 out_drv: