[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>
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@ -113,10 +113,16 @@ EXPORT_SYMBOL_GPL(rtc_device_register);
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*/
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void rtc_device_unregister(struct rtc_device *rtc)
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{
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if (class_device_get(&rtc->class_dev) != NULL) {
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mutex_lock(&rtc->ops_lock);
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/* remove innards of this RTC, then disable it, before
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* letting any rtc_class_open() users access it again
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*/
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class_device_unregister(&rtc->class_dev);
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rtc->ops = NULL;
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mutex_unlock(&rtc->ops_lock);
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class_device_unregister(&rtc->class_dev);
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class_device_put(&rtc->class_dev);
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}
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}
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EXPORT_SYMBOL_GPL(rtc_device_unregister);
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@ -179,7 +179,7 @@ struct class_device *rtc_class_open(char *name)
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down(&rtc_class->sem);
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list_for_each_entry(class_dev_tmp, &rtc_class->children, node) {
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if (strncmp(class_dev_tmp->class_id, name, BUS_ID_SIZE) == 0) {
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class_dev = class_dev_tmp;
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class_dev = class_device_get(class_dev_tmp);
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break;
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}
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}
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@ -197,6 +197,7 @@ EXPORT_SYMBOL_GPL(rtc_class_open);
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void rtc_class_close(struct class_device *class_dev)
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{
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module_put(to_rtc_device(class_dev)->owner);
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class_device_put(class_dev);
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}
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EXPORT_SYMBOL_GPL(rtc_class_close);
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