linux-kernel - [PATCH/RFC 1/6] alarmtimer: Postpone wake-up source registration until really available

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Message-Id: <1487622809-25127-2-git-send-email-geert+renesas@glider.be>
Date:   Mon, 20 Feb 2017 21:33:24 +0100
From:   Geert Uytterhoeven <geert+renesas@...der.be>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Mark Rutland <mark.rutland@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        Lina Iyer <lina.iyer@...aro.org>,
        John Stultz <john.stultz@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Rob Herring <robh+dt@...nel.org>
Cc:     Magnus Damm <magnus.damm@...il.com>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-renesas-soc@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH/RFC 1/6] alarmtimer: Postpone wake-up source registration until really available

Currently the alarmtimer registers a wake-up source unconditionally,
regardless of the system having a (wake-up capable) RTC or not.
To fix this, postpone registration until a wake-up capable RTC device is
added.

After this, the alarmtimer no longer shows up in
/sys/kernel/debug/wakeup_sources, unless it is available for real.

Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
---
 kernel/time/alarmtimer.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index e6dc9a538efa2116..5e0ce78607da5b5d 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -82,6 +82,7 @@ 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;
@@ -91,13 +92,20 @@ 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;
 }
 
@@ -908,7 +916,6 @@ static int __init alarmtimer_init(void)
 		error = PTR_ERR(pdev);
 		goto out_drv;
 	}
-	ws = wakeup_source_register("alarmtimer");
 	return 0;
 
 out_drv:
-- 
2.7.4