powerpc/eeh: Allow to purge EEH events

On PowerNV platform, we might run into the situation where subsequent
events are duplicated events of former one, which is being processed.
For the case, we need the function implemented by the patch to purge
EEH events accordingly.
Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/eeh_event.h

@@ -33,6 +33,7 @@ struct eeh_event {
 
 int eeh_event_init(void);
 int eeh_send_failure_event(struct eeh_pe *pe);
+void eeh_remove_event(struct eeh_pe *pe);
 void eeh_handle_event(struct eeh_pe *pe);
 
 #endif /* __KERNEL__ */

arch/powerpc/kernel/eeh_event.c

@@ -142,3 +142,40 @@ int eeh_send_failure_event(struct eeh_pe *pe)
 
 	return 0;
 }
+
+/**
+ * eeh_remove_event - Remove EEH event from the queue
+ * @pe: Event binding to the PE
+ *
+ * On PowerNV platform, we might have subsequent coming events
+ * is part of the former one. For that case, those subsequent
+ * coming events are totally duplicated and unnecessary, thus
+ * they should be removed.
+ */
+void eeh_remove_event(struct eeh_pe *pe)
+{
+	unsigned long flags;
+	struct eeh_event *event, *tmp;
+
+	spin_lock_irqsave(&eeh_eventlist_lock, flags);
+	list_for_each_entry_safe(event, tmp, &eeh_eventlist, list) {
+		/*
+		 * If we don't have valid PE passed in, that means
+		 * we already have event corresponding to dead IOC
+		 * and all events should be purged.
+		 */
+		if (!pe) {
+			list_del(&event->list);
+			kfree(event);
+		} else if (pe->type & EEH_PE_PHB) {
+			if (event->pe && event->pe->phb == pe->phb) {
+				list_del(&event->list);
+				kfree(event);
+			}
+		} else if (event->pe == pe) {
+			list_del(&event->list);
+			kfree(event);
+		}
+	}
+	spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
+}