From 4c8baa02d36379507afd17bdea87aabe0aa32ed3 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Sat, 22 Jul 2023 15:25:30 +0100 Subject: [PATCH] util/interval-tree: Use qatomic_set_mb in rb_link_node Ensure that the stores to rb_left and rb_right are complete before inserting the new node into the tree. Otherwise a concurrent reader could see garbage in the new leaf. Cc: qemu-stable@nongnu.org Reviewed-by: Peter Maydell Signed-off-by: Richard Henderson --- util/interval-tree.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/util/interval-tree.c b/util/interval-tree.c index 5a0ad21b2d..759562db7d 100644 --- a/util/interval-tree.c +++ b/util/interval-tree.c @@ -128,7 +128,11 @@ static inline void rb_link_node(RBNode *node, RBNode *parent, RBNode **rb_link) node->rb_parent_color = (uintptr_t)parent; node->rb_left = node->rb_right = NULL; - qatomic_set(rb_link, node); + /* + * Ensure that node is initialized before insertion, + * as viewed by a concurrent search. + */ + qatomic_set_mb(rb_link, node); } static RBNode *rb_next(RBNode *node)