[PATCH] add hlist_replace_rcu()

Add list_replace_rcu: replace old entry by new one.

Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 25 insertions, 1 deletions

diff --git a/include/linux/list.h b/include/linux/list.h
index fbfca73355a3..8e3388284530 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -202,12 +202,15 @@ static inline void list_del_rcu(struct list_head *entry)
  *
  * The old entry will be replaced with the new entry atomically.
  */
-static inline void list_replace_rcu(struct list_head *old, struct list_head *new){
+static inline void list_replace_rcu(struct list_head *old,
+                                struct list_head *new)
+{
         new->next = old->next;
         new->prev = old->prev;
         smp_wmb();
         new->next->prev = new;
         new->prev->next = new;
+        old->prev = LIST_POISON2;
 }
 
 /**
@@ -578,6 +581,27 @@ static inline void hlist_del_init(struct hlist_node *n)
         }
 }
 
+/*
+ * hlist_replace_rcu - replace old entry by new one
+ * @old : the element to be replaced
+ * @new : the new element to insert
+ *
+ * The old entry will be replaced with the new entry atomically.
+ */
+static inline void hlist_replace_rcu(struct hlist_node *old,
+                                        struct hlist_node *new)
+{
+        struct hlist_node *next = old->next;
+
+        new->next = next;
+        new->pprev = old->pprev;
+        smp_wmb();
+        if (next)
+                new->next->pprev = &new->next;
+        *new->pprev = new;
+        old->pprev = LIST_POISON2;
+}
+
 static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
 {
         struct hlist_node *first = h->first;