urcu: add cds_list_for_each_entry_safe_from macro

Same as cds_list_for_each_entry_safe, but starts at an arbitrary point
within the list instead of at the head.

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/urcu/list.h b/urcu/list.h
index b4962b445dfbc766ee229923b0af97f0f16beadf..4aaf869351fea0a8644f696ed294482de6a179d8 100644 (file)
--- a/urcu/list.h
+++ b/urcu/list.h
@@ -171,6 +171,15 @@ void cds_list_splice(struct cds_list_head *add, struct cds_list_head *head)
                &pos->member != (head); \
                pos = p, p = cds_list_entry(pos->member.next, __typeof__(*pos), member))
 
+/*
+ * Same as cds_list_for_each_entry_safe, but starts from "pos" which should
+ * point to an entry within the list.
+ */
+#define cds_list_for_each_entry_safe_from(pos, p, head, member) \
+        for (p = cds_list_entry(pos->member.next, __typeof__(*pos), member); \
+                &pos->member != (head); \
+                pos = p, p = cds_list_entry(pos->member.next, __typeof__(*pos), member))
+
 static inline
 int cds_list_empty(struct cds_list_head *head)
 {