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[PATCH] rtc_cmos oops fix

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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>
This commit is contained in:
David Brownell 2007-02-28 20:12:40 -08:00 committed by Linus Torvalds
parent 0478e62e8a
commit e109ebd1ee
2 changed files with 12 additions and 5 deletions
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14
drivers/rtc/class.c
View File

@ -113,10 +113,16 @@ EXPORT_SYMBOL_GPL(rtc_device_register);
*/ */
void rtc_device_unregister(struct rtc_device *rtc) void rtc_device_unregister(struct rtc_device *rtc)
{ {
mutex_lock(&rtc->ops_lock); if (class_device_get(&rtc->class_dev) != NULL) {
rtc->ops = NULL; mutex_lock(&rtc->ops_lock);
mutex_unlock(&rtc->ops_lock); /* remove innards of this RTC, then disable it, before
class_device_unregister(&rtc->class_dev); * 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); EXPORT_SYMBOL_GPL(rtc_device_unregister);

3
drivers/rtc/interface.c
View File

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