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From:   "Rafael J. Wysocki" <rjw@rjwysocki.net>
To:     Alexandre Belloni <alexandre.belloni@bootlin.com>,
        linux-rtc@vger.kernel.org
Cc:     Linux ACPI <linux-acpi@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux PM <linux-pm@vger.kernel.org>,
        Zhang Rui <rui.zhang@intel.com>,
        Alessandro Zummo <a.zummo@towertech.it>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Subject: [PATCH v1 5/5] rtc: rtc-cmos: Disable ACPI RTC event on removal
Date:   Mon, 07 Nov 2022 21:03:06 +0100
Message-ID: <2219830.iZASKD2KPV@kreacher>
In-Reply-To: <2276401.ElGaqSPkdT@kreacher>
References: <2276401.ElGaqSPkdT@kreacher>
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From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Make cmos_do_remove() drop the ACPI RTC fixed event handler so as to
prevent it from operating on stale data in case the event triggers
after driver removal.

While at it, make cmos_do_remove() also clear the driver data pointer
of the device and make cmos_acpi_wake_setup() do that in the error path
too.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/rtc/rtc-cmos.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

Index: linux-pm/drivers/rtc/rtc-cmos.c
===================================================================
--- linux-pm.orig/drivers/rtc/rtc-cmos.c
+++ linux-pm/drivers/rtc/rtc-cmos.c
@@ -798,6 +798,12 @@ static inline void acpi_rtc_event_setup(
 	acpi_disable_event(ACPI_EVENT_RTC, 0);
 }
 
+static inline void acpi_rtc_event_cleanup(void)
+{
+	if (!acpi_disabled)
+		acpi_remove_fixed_event_handler(ACPI_EVENT_RTC, rtc_handler);
+}
+
 static void rtc_wake_on(struct device *dev)
 {
 	acpi_clear_event(ACPI_EVENT_RTC);
@@ -884,6 +890,10 @@ static inline void acpi_rtc_event_setup(
 {
 }
 
+static inline void acpi_rtc_event_cleanup(void)
+{
+}
+
 static inline void cmos_acpi_wake_setup(struct device *dev)
 {
 }
@@ -1109,6 +1119,7 @@ cleanup2:
 		free_irq(rtc_irq, cmos_rtc.rtc);
 cleanup1:
 	cmos_rtc.dev = NULL;
+	dev_set_drvdata(dev, NULL);
 cleanup0:
 	if (RTC_IOMAPPED)
 		release_region(ports->start, resource_size(ports));
@@ -1138,6 +1149,9 @@ static void cmos_do_remove(struct device
 			hpet_unregister_irq_handler(cmos_interrupt);
 	}
 
+	if (!dev_get_platdata(dev))
+		acpi_rtc_event_cleanup();
+
 	cmos->rtc = NULL;
 
 	ports = cmos->iomem;
@@ -1148,6 +1162,7 @@ static void cmos_do_remove(struct device
 	cmos->iomem = NULL;
 
 	cmos->dev = NULL;
+	dev_set_drvdata(dev, NULL);
 }
 
 static int cmos_aie_poweroff(struct device *dev)