PM: PM QOS update fix

This update handles a use case where pm_qos update requests need to
silently fail if the update is being sent to a handle that is NULL.

The problem was that the original pm_qos silently fails when a request
update is passed to a parameter that has not been added to the list yet.
This update restores that behavior.
Signed-off-by: markgross <markgross@thegnar.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

kernel/pm_qos_params.c

@@ -252,6 +252,7 @@ void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req,
 	int pending_update = 0;
 	s32 temp;
 
+	if (pm_qos_req) { /*guard against callers passing in null */
 		spin_lock_irqsave(&pm_qos_lock, flags);
 		if (new_value == PM_QOS_DEFAULT_VALUE)
 			temp = pm_qos_array[pm_qos_req->pm_qos_class]->default_value;
@@ -265,6 +266,7 @@ void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req,
 		spin_unlock_irqrestore(&pm_qos_lock, flags);
 		if (pending_update)
 			update_target(pm_qos_req->pm_qos_class);
+	}
 }
 EXPORT_SYMBOL_GPL(pm_qos_update_request);