Peter Zijlstra a écrit :

On Wed, 2008-10-29 at 15:36 +0100, Eric Dumazet wrote:

quoted

+/**
+ * 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))
+

why _safenext and not _safe like hlist_for_each_entry_safe() which also
keeps a next pointer?

Also note the difference in argument order between these two.

Yes, this one is going to vanish soon.