lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
 
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Fri, 20 Nov 2015 13:21:55 -0800
From:	Tom Herbert <tom@...bertland.com>
To:	<davem@...emloft.net>, <netdev@...r.kernel.org>
CC:	<kernel-team@...com>, <davewatson@...com>,
	<alexei.starovoitov@...il.com>
Subject: [PATCH net-next 1/6] rcu: Add list_next_or_null_rcu

This is a convenience function that returns the next entry in an RCU
list or NULL if at the end of the list.

Signed-off-by: Tom Herbert <tom@...bertland.com>
---
 include/linux/rculist.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 5ed5409..a9376fd 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -290,6 +290,27 @@ static inline void list_splice_init_rcu(struct list_head *list,
 })
 
 /**
+ * list_next_or_null_rcu - get the first element from a list
+ * @head:	the head for the list.
+ * @ptr:        the list head to take the next element from.
+ * @type:       the type of the struct this is embedded in.
+ * @member:     the name of the list_head within the struct.
+ *
+ * Note that if the ptr is at the end of the list, NULL is returned.
+ *
+ * This primitive may safely run concurrently with the _rcu list-mutation
+ * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
+ */
+#define list_next_or_null_rcu(head, ptr, type, member) \
+({ \
+	struct list_head *__head = (head); \
+	struct list_head *__ptr = (ptr); \
+	struct list_head *__next = READ_ONCE(__ptr->next); \
+	likely(__next != __head) ? list_entry_rcu(__next, type, \
+						  member) : NULL; \
+})
+
+/**
  * list_for_each_entry_rcu	-	iterate over rcu list of given type
  * @pos:	the type * to use as a loop cursor.
  * @head:	the head for your list.
-- 
2.4.6

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Powered by blists - more mailing lists