X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=include%2Flinux%2Frculist.h;h=e649bd3f2c976c3f5bed58c067c351a336403e75;hb=6cd61c0baa8bce32271226198b46c67a7a05d108;hp=aa9b3eb1568325bbcd4a80e53fa09e82a8b566c6;hpb=82524746c27fa418c250a56dd7606b9d3fc79826;p=safe%2Fjmp%2Flinux-2.6

diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index aa9b3eb..e649bd3 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -7,6 +7,7 @@
  * RCU-protected list version
  */
 #include <linux/list.h>
+#include <linux/rcupdate.h>
 
 /*
  * Insert a new entry between two known consecutive entries.
@@ -19,9 +20,8 @@ static inline void __list_add_rcu(struct list_head *new,
 {
 	new->next = next;
 	new->prev = prev;
-	smp_wmb();
+	rcu_assign_pointer(prev->next, new);
 	next->prev = new;
-	prev->next = new;
 }
 
 /**
@@ -98,6 +98,34 @@ static inline void list_del_rcu(struct list_head *entry)
 }
 
 /**
+ * hlist_del_init_rcu - deletes entry from hash list with re-initialization
+ * @n: the element to delete from the hash list.
+ *
+ * Note: list_unhashed() on the node return true after this. It is
+ * useful for RCU based read lockfree traversal if the writer side
+ * must know if the list entry is still hashed or already unhashed.
+ *
+ * In particular, it means that we can not poison the forward pointers
+ * that may still be used for walking the hash list and we can only
+ * zero the pprev pointer so list_unhashed() will return true after
+ * this.
+ *
+ * The caller must take whatever precautions are necessary (such as
+ * holding appropriate locks) to avoid racing with another
+ * list-mutation primitive, such as hlist_add_head_rcu() 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_rcu().
+ */
+static inline void hlist_del_init_rcu(struct hlist_node *n)
+{
+	if (!hlist_unhashed(n)) {
+		__hlist_del(n);
+		n->pprev = NULL;
+	}
+}
+
+/**
  * list_replace_rcu - replace old entry by new one
  * @old : the element to be replaced
  * @new : the new element to insert
@@ -110,9 +138,8 @@ static inline void list_replace_rcu(struct list_head *old,
 {
 	new->next = old->next;
 	new->prev = old->prev;
-	smp_wmb();
+	rcu_assign_pointer(new->prev->next, new);
 	new->next->prev = new;
-	new->prev->next = new;
 	old->prev = LIST_POISON2;
 }
 
@@ -166,47 +193,15 @@ static inline void list_splice_init_rcu(struct list_head *list,
 	 */
 
 	last->next = at;
-	smp_wmb();
-	head->next = first;
+	rcu_assign_pointer(head->next, first);
 	first->prev = head;
 	at->prev = last;
 }
 
-/**
- * list_for_each_rcu	-	iterate over an rcu-protected list
- * @pos:	the &struct list_head to use as a loop cursor.
- * @head:	the head for your list.
- *
- * This list-traversal primitive may safely run concurrently with
- * the _rcu list-mutation primitives such as list_add_rcu()
- * as long as the traversal is guarded by rcu_read_lock().
- */
-#define list_for_each_rcu(pos, head) \
-	for (pos = (head)->next; \
-		prefetch(rcu_dereference(pos)->next), pos != (head); \
-		pos = pos->next)
-
 #define __list_for_each_rcu(pos, head) \
-	for (pos = (head)->next; \
-		rcu_dereference(pos) != (head); \
-		pos = pos->next)
-
-/**
- * list_for_each_safe_rcu
- * @pos:	the &struct list_head to use as a loop cursor.
- * @n:		another &struct list_head to use as temporary storage
- * @head:	the head for your list.
- *
- * Iterate over an rcu-protected list, safe against removal of list entry.
- *
- * This list-traversal primitive may safely run concurrently with
- * the _rcu list-mutation primitives such as list_add_rcu()
- * as long as the traversal is guarded by rcu_read_lock().
- */
-#define list_for_each_safe_rcu(pos, n, head) \
-	for (pos = (head)->next; \
-		n = rcu_dereference(pos)->next, pos != (head); \
-		pos = n)
+	for (pos = rcu_dereference((head)->next); \
+		pos != (head); \
+		pos = rcu_dereference(pos->next))
 
 /**
  * list_for_each_entry_rcu	-	iterate over rcu list of given type
@@ -219,10 +214,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
  * as long as the traversal is guarded by rcu_read_lock().
  */
 #define list_for_each_entry_rcu(pos, head, member) \
-	for (pos = list_entry((head)->next, typeof(*pos), member); \
-		prefetch(rcu_dereference(pos)->member.next), \
-			&pos->member != (head); \
-		pos = list_entry(pos->member.next, typeof(*pos), member))
+	for (pos = list_entry(rcu_dereference((head)->next), typeof(*pos), member); \
+		prefetch(pos->member.next), &pos->member != (head); \
+		pos = list_entry(rcu_dereference(pos->member.next), typeof(*pos), member))
 
 
 /**
@@ -237,9 +231,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
  * as long as the traversal is guarded by rcu_read_lock().
  */
 #define list_for_each_continue_rcu(pos, head) \
-	for ((pos) = (pos)->next; \
-		prefetch(rcu_dereference((pos))->next), (pos) != (head); \
-		(pos) = (pos)->next)
+	for ((pos) = rcu_dereference((pos)->next); \
+		prefetch((pos)->next), (pos) != (head); \
+		(pos) = rcu_dereference((pos)->next))
 
 /**
  * hlist_del_rcu - deletes entry from hash list without re-initialization
@@ -280,10 +274,9 @@ static inline void hlist_replace_rcu(struct hlist_node *old,
 
 	new->next = next;
 	new->pprev = old->pprev;
-	smp_wmb();
+	rcu_assign_pointer(*new->pprev, new);
 	if (next)
 		new->next->pprev = &new->next;
-	*new->pprev = new;
 	old->pprev = LIST_POISON2;
 }
 
@@ -310,12 +303,12 @@ static inline void hlist_add_head_rcu(struct hlist_node *n,
 					struct hlist_head *h)
 {
 	struct hlist_node *first = h->first;
+
 	n->next = first;
 	n->pprev = &h->first;
-	smp_wmb();
+	rcu_assign_pointer(h->first, n);
 	if (first)
 		first->pprev = &n->next;
-	h->first = n;
 }
 
 /**
@@ -341,9 +334,8 @@ static inline void hlist_add_before_rcu(struct hlist_node *n,
 {
 	n->pprev = next->pprev;
 	n->next = next;
-	smp_wmb();
+	rcu_assign_pointer(*(n->pprev), n);
 	next->pprev = &n->next;
-	*(n->pprev) = n;
 }
 
 /**
@@ -369,8 +361,7 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
 {
 	n->next = prev->next;
 	n->pprev = &prev->next;
-	smp_wmb();
-	prev->next = n;
+	rcu_assign_pointer(prev->next, n);
 	if (n->next)
 		n->next->pprev = &n->next;
 }
@@ -387,10 +378,10 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
  * as long as the traversal is guarded by rcu_read_lock().
  */
 #define hlist_for_each_entry_rcu(tpos, pos, head, member)		 \
-	for (pos = (head)->first;					 \
-	     rcu_dereference(pos) && ({ prefetch(pos->next); 1; }) &&	 \
+	for (pos = rcu_dereference((head)->first);			 \
+		pos && ({ prefetch(pos->next); 1; }) &&			 \
 		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
-	     pos = pos->next)
+		pos = rcu_dereference(pos->next))
 
 #endif	/* __KERNEL__ */
 #endif