udp: introduce sk_for_each_rcu_safenext()

[~andy/linux] / include / linux / rculist.h

diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index e649bd3f2c976c3f5bed58c067c351a336403e75..3ba2998b22ba64f33b127d7ac368b1ac8196a03c 100644 (file)
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -383,5 +383,22 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
                ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
                pos = rcu_dereference(pos->next))
 
+/**
+ * hlist_for_each_entry_rcu_safenext - iterate over rcu list of given type
+ * @tpos:      the type * to use as a loop cursor.
+ * @pos:       the &struct hlist_node to use as a loop cursor.
+ * @head:      the head for your list.
+ * @member:    the name of the hlist_node within the struct.
+ * @next:       the &struct hlist_node to use as a next cursor
+ *
+ * Special version of hlist_for_each_entry_rcu that make sure
+ * each next pointer is fetched before each iteration.
+ */
+#define hlist_for_each_entry_rcu_safenext(tpos, pos, head, member, next) \
+       for (pos = rcu_dereference((head)->first);                       \
+               pos && ({ next = pos->next; smp_rmb(); prefetch(next); 1; }) && \
+               ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
+               pos = rcu_dereference(next))
+
 #endif /* __KERNEL__ */
 #endif