From e109ebd1eed2b91e3c9bb3b42cc27961f0dc22b3 Mon Sep 17 00:00:00 2001 From: David Brownell Date: Wed, 28 Feb 2007 20:12:40 -0800 Subject: [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 Cc: Alessandro Zummo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/rtc/class.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'drivers/rtc/class.c') diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c index 7a0d8ee2de9..04aaa634723 100644 --- a/drivers/rtc/class.c +++ b/drivers/rtc/class.c @@ -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); -- cgit v1.2.3-70-g09d2