Commit e109ebd1 authored Feb 28, 2007 by David Brownell Committed by Linus Torvalds Mar 01, 2007

[PATCH] rtc_cmos oops fix

Fix an oops on the rtc_device_unregister() path by waiting until the last
moment before nulling the rtc->ops vector. Fix some potential oopses by
having the rtc_class_open()/rtc_class_close() interface increase the RTC's
reference count while an RTC handle is available outside the RTC framework.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 0478e62e

drivers/rtc/class.c

+10 −4

Original line number	Diff line number	Diff line
		@@ -113,10 +113,16 @@ EXPORT_SYMBOL_GPL(rtc_device_register);
		*/
		void rtc_device_unregister(struct rtc_device *rtc)
		{
		if (class_device_get(&rtc->class_dev) != NULL) {
		mutex_lock(&rtc->ops_lock);
		/* remove innards of this RTC, then disable it, before
		* letting any rtc_class_open() users access it again
		*/
		class_device_unregister(&rtc->class_dev);
		rtc->ops = NULL;
		mutex_unlock(&rtc->ops_lock);
		class_device_unregister(&rtc->class_dev);
		class_device_put(&rtc->class_dev);
		}
		}
		EXPORT_SYMBOL_GPL(rtc_device_unregister);

drivers/rtc/interface.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -179,7 +179,7 @@ struct class_device rtc_class_open(char name)
		down(&rtc_class->sem);
		list_for_each_entry(class_dev_tmp, &rtc_class->children, node) {
		if (strncmp(class_dev_tmp->class_id, name, BUS_ID_SIZE) == 0) {
		class_dev = class_dev_tmp;
		class_dev = class_device_get(class_dev_tmp);
		break;
		}
		}
		@@ -197,6 +197,7 @@ EXPORT_SYMBOL_GPL(rtc_class_open);
		void rtc_class_close(struct class_device *class_dev)
		{
		module_put(to_rtc_device(class_dev)->owner);
		class_device_put(class_dev);
		}
		EXPORT_SYMBOL_GPL(rtc_class_close);