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authorDavid Howells <dhowells@redhat.com>2016-07-01 07:53:51 +0100
committerDavid Howells <dhowells@redhat.com>2016-07-06 10:51:14 +0100
commitc1adf20052d80f776849fa2c1acb472cdeb7786c (patch)
treee73407fdc52ab77e9666ae7798c8b38b6da1ed09 /lib
parent1291e9d1084506c5cba6313ce809d7516bb5868a (diff)
downloadlinux-stericsson-c1adf20052d80f776849fa2c1acb472cdeb7786c.tar.gz
Introduce rb_replace_node_rcu()
Implement an RCU-safe variant of rb_replace_node() and rearrange rb_replace_node() to do things in the same order. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/rbtree.c26
1 files changed, 24 insertions, 2 deletions
diff --git a/lib/rbtree.c b/lib/rbtree.c
index 1356454e36de..eb8a19fee110 100644
--- a/lib/rbtree.c
+++ b/lib/rbtree.c
@@ -539,17 +539,39 @@ void rb_replace_node(struct rb_node *victim, struct rb_node *new,
{
struct rb_node *parent = rb_parent(victim);
+ /* Copy the pointers/colour from the victim to the replacement */
+ *new = *victim;
+
/* Set the surrounding nodes to point to the replacement */
- __rb_change_child(victim, new, parent, root);
if (victim->rb_left)
rb_set_parent(victim->rb_left, new);
if (victim->rb_right)
rb_set_parent(victim->rb_right, new);
+ __rb_change_child(victim, new, parent, root);
+}
+EXPORT_SYMBOL(rb_replace_node);
+
+void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
+ struct rb_root *root)
+{
+ struct rb_node *parent = rb_parent(victim);
/* Copy the pointers/colour from the victim to the replacement */
*new = *victim;
+
+ /* Set the surrounding nodes to point to the replacement */
+ if (victim->rb_left)
+ rb_set_parent(victim->rb_left, new);
+ if (victim->rb_right)
+ rb_set_parent(victim->rb_right, new);
+
+ /* Set the parent's pointer to the new node last after an RCU barrier
+ * so that the pointers onwards are seen to be set correctly when doing
+ * an RCU walk over the tree.
+ */
+ __rb_change_child_rcu(victim, new, parent, root);
}
-EXPORT_SYMBOL(rb_replace_node);
+EXPORT_SYMBOL(rb_replace_node_rcu);
static struct rb_node *rb_left_deepest_node(const struct rb_node *node)
{