From: Jiri Pirko <jiri@resnulli.us>
Date: Wed, 29 May 2013 05:02:56 +0000 (+0000)
Subject: list: introduce list_first_entry_or_null
X-Git-Tag: firefly_0821_release~3680^2~363^2~17
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=6d7581e62f8be462440d7b22c6361f7c9fa4902b;p=firefly-linux-kernel-4.4.55.git

list: introduce list_first_entry_or_null

non-rcu variant of list_first_or_null_rcu

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/include/linux/list.h b/include/linux/list.h
index 6a1f8df9144b..b83e5657365a 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -361,6 +361,17 @@ static inline void list_splice_tail_init(struct list_head *list,
 #define list_first_entry(ptr, type, member) \
 	list_entry((ptr)->next, type, member)
 
+/**
+ * list_first_entry_or_null - get the first element from a list
+ * @ptr:	the list head to take the element from.
+ * @type:	the type of the struct this is embedded in.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Note that if the list is empty, it returns NULL.
+ */
+#define list_first_entry_or_null(ptr, type, member) \
+	(!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
+
 /**
  * list_for_each	-	iterate over a list
  * @pos:	the &struct list_head to use as a loop cursor.