vserver 1.9.3

[linux-2.6.git] / include / linux / list.h

diff --git a/include/linux/list.h b/include/linux/list.h
index 33b863b..94bed0f 100644 (file)
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -195,6 +195,21 @@ static inline void list_del_rcu(struct list_head *entry)
        entry->prev = LIST_POISON2;
 }
 
+/*
+ * list_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 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;
+}
+
 /**
  * list_del_init - deletes entry from list and reinitialize it.
  * @entry: the element to delete from the list.
@@ -420,11 +435,11 @@ static inline void list_splice_init(struct list_head *list,
  */
 #define list_for_each_rcu(pos, head) \
        for (pos = (head)->next, prefetch(pos->next); pos != (head); \
-               pos = pos->next, ({ smp_read_barrier_depends(); 0;}), prefetch(pos->next))
+               pos = rcu_dereference(pos->next), prefetch(pos->next))
 
 #define __list_for_each_rcu(pos, head) \
        for (pos = (head)->next; pos != (head); \
-               pos = pos->next, ({ smp_read_barrier_depends(); 0;}))
+               pos = rcu_dereference(pos->next))
 
 /**
  * list_for_each_safe_rcu      -       iterate over an rcu-protected list safe
@@ -439,7 +454,7 @@ static inline void list_splice_init(struct list_head *list,
  */
 #define list_for_each_safe_rcu(pos, n, head) \
        for (pos = (head)->next, n = pos->next; pos != (head); \
-               pos = n, ({ smp_read_barrier_depends(); 0;}), n = pos->next)
+               pos = rcu_dereference(n), n = pos->next)
 
 /**
  * list_for_each_entry_rcu     -       iterate over rcu list of given type
@@ -455,8 +470,8 @@ static inline void list_splice_init(struct list_head *list,
        for (pos = list_entry((head)->next, typeof(*pos), member),      \
                     prefetch(pos->member.next);                        \
             &pos->member != (head);                                    \
-            pos = list_entry(pos->member.next, typeof(*pos), member),  \
-                    ({ smp_read_barrier_depends(); 0;}),               \
+            pos = rcu_dereference(list_entry(pos->member.next,         \
+                                       typeof(*pos), member)),         \
                     prefetch(pos->member.next))
 
 
@@ -472,7 +487,7 @@ static inline void list_splice_init(struct list_head *list,
  */
 #define list_for_each_continue_rcu(pos, head) \
        for ((pos) = (pos)->next, prefetch((pos)->next); (pos) != (head); \
-               (pos) = (pos)->next, ({ smp_read_barrier_depends(); 0;}), prefetch((pos)->next))
+               (pos) = rcu_dereference((pos)->next), prefetch((pos)->next))
 
 /*
  * Double linked lists with a single pointer list head.
@@ -578,12 +593,9 @@ static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
  * or hlist_del_rcu(), running on this same list.
  * However, it is perfectly legal to run concurrently with
  * the _rcu list-traversal primitives, such as
- * hlist_for_each_entry(), but only if smp_read_barrier_depends()
- * is used to prevent memory-consistency problems on Alpha CPUs.
- * Regardless of the type of CPU, the list-traversal primitive
- * must be guarded by rcu_read_lock().
- *
- * OK, so why don't we have an hlist_for_each_entry_rcu()???
+ * hlist_for_each_rcu(), used to prevent memory-consistency
+ * problems on Alpha CPUs.  Regardless of the type of CPU, the
+ * list-traversal primitive must be guarded by rcu_read_lock().
  */
 static inline void hlist_add_head_rcu(struct hlist_node *n,
                                        struct hlist_head *h)
@@ -628,6 +640,10 @@ static inline void hlist_add_after(struct hlist_node *n,
        for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
             pos = n)
 
+#define hlist_for_each_rcu(pos, head) \
+       for ((pos) = (head)->first; pos && ({ prefetch((pos)->next); 1; }); \
+               (pos) = rcu_dereference((pos)->next))
+
 /**
  * hlist_for_each_entry        - iterate over list of given type
  * @tpos:      the type * to use as a loop counter.
@@ -693,7 +709,7 @@ static inline void hlist_add_after(struct hlist_node *n,
        for (pos = (head)->first;                                        \
             pos && ({ prefetch(pos->next); 1;}) &&                      \
                ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
-            pos = pos->next, ({ smp_read_barrier_depends(); 0; }) )
+            pos = rcu_dereference(pos->next))
 
 #else
 #warning "don't include kernel headers in userspace"