On 03/22/2011 04:19 PM, Steven Rostedt wrote: > > Looks to me that the mutex_lock() in _notifier_call_chain needs to be a > mutex_lock_nested(). > > The "_nested()" versions are when you have the same type of mutex taken > but belonging to two different instances. Like you have here: > > blocking_notifier_call_chain(&rdev->notifier, event, NULL); > > /* now notify regulator we supply */ > list_for_each_entry(_rdev, &rdev->supply_list, slist) { > mutex_lock(&_rdev->mutex); > _notifier_call_chain(_rdev, event, data); > mutex_unlock(&_rdev->mutex); > } > > The rdev->mutex is already held, so we don't need to take it to call the > blocking_notifier_call_chain() with the rdev->notifier. But then the > list of rdev's in the rdev->supply_list are different instances but we > are still taking the same type of lock. lockdep treats all instances of > the same lock the same, so to lockdep this looks like a deadlock. To > teach lockdep that this is a different instance, simply use > mutex_lock_nested() instead. > > -- Steve > > There seem to be very few uses of mutex_lock_nested() in the kernel. Most of them use subclass = SINGLE_DEPTH_NESTING. Would this be sufficient for usage in the regulator core in _notifier_call_chain (and perhaps other places) or should some other subclass be used? Thanks, David -- Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum. -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html