[CRIU] [PATCH] pstree: use RB_EMPTY_NODE to check that node is not linked

[Pavel Tikhomirov]

When new rb_root is created for pidns it is initialized with
RB_ROOT, so ns->pid.rb_root.rb_node is NULL at first. Later
then insert first node in lookup_create_pid() to these rb-tree
it will have (NULL & color) in node->rb_parent_color.

So the check "!rb_parent(&found->ns[i].node)" will be true for
the rb-tree's root node, and criu will fail lookup these node.

We haven't hit that yet as to get to these check we need task in
at least two levels of pidns which at the same time is the root
in rb-tree on e.g. level 0.

Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
 criu/pstree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/criu/pstree.c b/criu/pstree.c
index 3206cf1..efff3d7 100644
--- a/criu/pstree.c
+++ b/criu/pstree.c
@@ -522,7 +522,7 @@ static struct pid *lookup_create_pid(pid_t *pid, int level, struct pid *pid_node
 	found = find_pid_or_place_in_hier(&ns->pid.rb_root.rb_node, pid[level-1], level-1, &parent, &new);
 	if (found) {
 		for (i = level - 2; i >= 0; i--)
-			if (pid[i] != found->ns[i].virt || !rb_parent(&found->ns[i].node)) {
+			if (pid[i] != found->ns[i].virt || RB_EMPTY_NODE(&found->ns[i].node)) {
 				pr_err("Wrong pid\n");
 				return NULL;
 			}
-- 
2.9.3