Commit 51218298 authored Aug 21, 2017 by Alexandre Belloni Committed by Thomas Gleixner Aug 31, 2017

alarmtimer: Ensure RTC module is not unloaded



When registering the rtc device to be used to handle alarm timers,
get_device is used to ensure the device doesn't go away but the module can
still be unloaded.

Call try_module_get to ensure the rtc driver will not go away.

Reported-and-tested-by: Michal Simek <monstr@monstr.eu>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Link: http://lkml.kernel.org/r/20170820220146.30969-1-alexandre.belloni@free-electrons.com

parent bc30658e

kernel/time/alarmtimer.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -28,6 +28,7 @@
		#include <linux/workqueue.h>
		#include <linux/freezer.h>
		#include <linux/compat.h>
		#include <linux/module.h>

		#include "posix-timers.h"

		@@ -103,6 +104,11 @@ static int alarmtimer_rtc_add_device(struct device *dev,

		spin_lock_irqsave(&rtcdev_lock, flags);
		if (!rtcdev) {
		if (!try_module_get(rtc->owner)) {
		spin_unlock_irqrestore(&rtcdev_lock, flags);
		return -1;
		}

		rtcdev = rtc;
		/* hold a reference so it doesn't go away */
		get_device(dev);