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>

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 0b8ff7d257ea290743f2d0ab0194488784bc56ef..73a2b476e59f3256387fe48097509bbda44c76af 100644 (file)
--- 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: