Commit e109ebd1 authored by David Brownell's avatar David Brownell Committed by Linus Torvalds

[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: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0478e62e
......@@ -113,10 +113,16 @@ EXPORT_SYMBOL_GPL(rtc_device_register);
*/
void rtc_device_unregister(struct rtc_device *rtc)
{
mutex_lock(&rtc->ops_lock);
rtc->ops = NULL;
mutex_unlock(&rtc->ops_lock);
class_device_unregister(&rtc->class_dev);
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_put(&rtc->class_dev);
}
}
EXPORT_SYMBOL_GPL(rtc_device_unregister);
......
......@@ -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);
......
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