linux-kernel - [PATCH v2] alarmtimer: Fix rebind failure

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Date:   Fri, 22 Sep 2023 09:12:08 +0100
From:   Biju Das <biju.das.jz@...renesas.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     Biju Das <biju.das.jz@...renesas.com>,
        John Stultz <jstultz@...gle.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Douglas Anderson <dianders@...omium.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Biju Das <biju.das.au@...il.com>, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Subject: [PATCH v2] alarmtimer: Fix rebind failure

The resources allocated in alarmtimer_rtc_add_device() are not freed
leading to re-bind failure for the endpoint driver. Fix this issue
by adding alarmtimer_rtc_remove_device().

Fixes: c79108bd19a8 ("alarmtimer: Make alarmtimer platform device child of RTC device")
Fixes: 7c94caca877b ("alarmtimer: Use wakeup source from alarmtimer platform device")
Signed-off-by: Biju Das <biju.das.jz@...renesas.com>
---
v1->v2:
 * Add fixes tag.
 * Replaced the variable rtc_pdev->alarmtimer_pdev
 * Added the check rtcdev == rtc before unregistering the real alarmtimer.
Note:
 This issue is found while adding irq support for built in RTC
 found on Renesas PMIC RAA215300 device. This issue should present
 on all RTC drivers which calls device_init_wakeup() in probe().
---
 kernel/time/alarmtimer.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 8d9f13d847f0..04d67de8b1fe 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -61,6 +61,7 @@ static DEFINE_SPINLOCK(freezer_delta_lock);
 /* rtc timer and device for setting alarm wakeups at suspend */
 static struct rtc_timer		rtctimer;
 static struct rtc_device	*rtcdev;
+static struct platform_device	*alarmtimer_pdev;
 static DEFINE_SPINLOCK(rtcdev_lock);
 
 /**
@@ -109,6 +110,7 @@ static int alarmtimer_rtc_add_device(struct device *dev)
 		}
 
 		rtcdev = rtc;
+		alarmtimer_pdev = pdev;
 		/* hold a reference so it doesn't go away */
 		get_device(dev);
 		pdev = NULL;
@@ -123,6 +125,22 @@ static int alarmtimer_rtc_add_device(struct device *dev)
 	return ret;
 }
 
+static void alarmtimer_rtc_remove_device(struct device *dev)
+{
+	struct rtc_device *rtc = to_rtc_device(dev);
+
+	if (rtcdev == rtc) {
+		module_put(rtc->owner);
+		if (device_may_wakeup(rtc->dev.parent))
+			device_init_wakeup(&alarmtimer_pdev->dev, false);
+
+		platform_device_unregister(alarmtimer_pdev);
+		put_device(dev);
+		alarmtimer_pdev = NULL;
+		rtcdev = NULL;
+	}
+}
+
 static inline void alarmtimer_rtc_timer_init(void)
 {
 	rtc_timer_init(&rtctimer, NULL, NULL);
@@ -130,6 +148,7 @@ static inline void alarmtimer_rtc_timer_init(void)
 
 static struct class_interface alarmtimer_rtc_interface = {
 	.add_dev = &alarmtimer_rtc_add_device,
+	.remove_dev = &alarmtimer_rtc_remove_device,
 };
 
 static int alarmtimer_rtc_interface_setup(void)
-- 
2.25.1