From e109ebd1eed2b91e3c9bb3b42cc27961f0dc22b3 Mon Sep 17 00:00:00 2001 From: David Brownell Date: Wed, 28 Feb 2007 20:12:40 -0800 Subject: [PATCH] [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 ++++++++++---- drivers/rtc/interface.c | 3 ++- 2 files changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c index 7a0d8ee2de9c..04aaa6347234 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); diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c index 6f11f6dfdd9d..ef40df0f169d 100644 --- a/drivers/rtc/interface.c +++ b/drivers/rtc/interface.c @@ -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); -- 2.20.1