Commit-ID: 7d86dccf28a3ae2f790f399fc82d4c82521fd078
Gitweb: http://git.kernel.org/tip/7d86dccf28a3ae2f790f399fc82d4c82521fd078
Author: Petko Manolov <petkan@xxxxxxxxxxxx>
AuthorDate: Mon, 12 Oct 2015 18:23:51 +0300
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Fri, 4 Dec 2015 12:34:32 -0800
list: Introduces generic list_splice_tail_init_rcu()
The list_splice_init_rcu() can be used as a stack onto which full lists
are pushed, but queue-like behavior is now needed by some security
policies. This requires a list_splice_tail_init_rcu().
This commit therefore supplies a list_splice_tail_init_rcu() by
pulling code common it and to list_splice_init_rcu() into a new
__list_splice_init_rcu() function. This new function is based on the
existing list_splice_init_rcu() implementation.
Signed-off-by: Petko Manolov <petkan@xxxxxxxxxxxx>
Cc: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
include/linux/rculist.h | 69 +++++++++++++++++++++++++++++++++++--------------
1 file changed, 49 insertions(+), 20 deletions(-)
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 5ed5409..e99d834 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -179,32 +179,31 @@ static inline void list_replace_rcu(struct list_head *old,
}
/**
- * list_splice_init_rcu - splice an RCU-protected list into an existing list.
+ * __list_splice_init_rcu - join an RCU-protected list into an existing list.
* @list: the RCU-protected list to splice
- * @head: the place in the list to splice the first list into
+ * @prev: points to the last element of the existing list
+ * @next: points to the first element of the existing list
* @sync: function to sync: synchronize_rcu(), synchronize_sched(), ...
*
- * @head can be RCU-read traversed concurrently with this function.
+ * The list pointed to by @prev and @next can be RCU-read traversed
+ * concurrently with this function.
*
* Note that this function blocks.
*
- * Important note: the caller must take whatever action is necessary to
- * prevent any other updates to @head. In principle, it is possible
- * to modify the list as soon as sync() begins execution.
- * If this sort of thing becomes necessary, an alternative version
- * based on call_rcu() could be created. But only if -really-
- * needed -- there is no shortage of RCU API members.
+ * Important note: the caller must take whatever action is necessary to prevent
+ * any other updates to the existing list. In principle, it is possible to
+ * modify the list as soon as sync() begins execution. If this sort of thing
+ * becomes necessary, an alternative version based on call_rcu() could be
+ * created. But only if -really- needed -- there is no shortage of RCU API
+ * members.
*/
-static inline void list_splice_init_rcu(struct list_head *list,
- struct list_head *head,
- void (*sync)(void))
+static inline void __list_splice_init_rcu(struct list_head *list,
+ struct list_head *prev,
+ struct list_head *next,
+ void (*sync)(void))
{
struct list_head *first = list->next;
struct list_head *last = list->prev;
- struct list_head *at = head->next;
-
- if (list_empty(list))
- return;
/*
* "first" and "last" tracking list, so initialize it. RCU readers
@@ -231,10 +230,40 @@ static inline void list_splice_init_rcu(struct list_head *list,
* this function.
*/
- last->next = at;
- rcu_assign_pointer(list_next_rcu(head), first);
- first->prev = head;
- at->prev = last;
+ last->next = next;
+ rcu_assign_pointer(list_next_rcu(prev), first);
+ first->prev = prev;
+ next->prev = last;
+}
+
+/**
+ * list_splice_init_rcu - splice an RCU-protected list into an existing list,
+ * designed for stacks.
+ * @list: the RCU-protected list to splice
+ * @head: the place in the existing list to splice the first list into
+ * @sync: function to sync: synchronize_rcu(), synchronize_sched(), ...
+ */
+static inline void list_splice_init_rcu(struct list_head *list,
+ struct list_head *head,
+ void (*sync)(void))
+{
+ if (!list_empty(list))
+ __list_splice_init_rcu(list, head, head->next, sync);
+}
+
+/**
+ * list_splice_tail_init_rcu - splice an RCU-protected list into an existing
+ * list, designed for queues.
+ * @list: the RCU-protected list to splice
+ * @head: the place in the existing list to splice the first list into
+ * @sync: function to sync: synchronize_rcu(), synchronize_sched(), ...
+ */
+static inline void list_splice_tail_init_rcu(struct list_head *list,
+ struct list_head *head,
+ void (*sync)(void))
+{
+ if (!list_empty(list))
+ __list_splice_init_rcu(list, head->prev, head, sync);
}
/**
--
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