linux-kernel - [PATCH 3.2 201/202] list: introduce list_first_entry_or

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Message-ID: <lsq.1489245348.466695862@decadent.org.uk>
Date:   Sat, 11 Mar 2017 15:15:48 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "David S. Miller" <davem@...emloft.net>,
        "Jiri Pirko" <jiri@...nulli.us>
Subject: [PATCH 3.2 201/202] list: introduce list_first_entry_or_null

3.2.87-rc2 review patch.  If anyone has any objections, please let me know.

------------------

From: Jiri Pirko <jiri@...nulli.us>

commit 6d7581e62f8be462440d7b22c6361f7c9fa4902b upstream.

non-rcu variant of list_first_or_null_rcu

Signed-off-by: Jiri Pirko <jiri@...nulli.us>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 include/linux/list.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

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
@@ -362,6 +362,17 @@ static inline void list_splice_tail_init(struct list_head *list,
 	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.
  * @head:	the head for your list.