git: 37370a6773cd - stable/13 - netgraph/ng_base: Renaming a node to the same name is a noop

[Lutz Donnerhacke]

The branch stable/13 has been updated by donner:

URL: https://cgit.FreeBSD.org/src/commit/?id=37370a6773cde7fcae063aed0a4cc024f95534bd

commit 37370a6773cde7fcae063aed0a4cc024f95534bd
Author:     Lutz Donnerhacke <donner at FreeBSD.org>
AuthorDate: 2021-05-04 19:20:39 +0000
Commit:     Lutz Donnerhacke <donner at FreeBSD.org>
CommitDate: 2021-06-10 09:29:34 +0000

    netgraph/ng_base: Renaming a node to the same name is a noop
    
    Detailed analysis in https://github.com/genneko/freebsd-vimage-jails/issues/2
    brought the problem down to a double call of ng_node_name() before and
    after a vnet move.  Because the name of the node is already known
    (occupied by itself), the second call fails.
    
    PR:             241954
    Reported by:    Paul Armstrong
    Differential Revision: https://reviews.freebsd.org/D30110
    
    (cherry picked from commit 0345fd891fe13a191fc0fae9463ea9458bfaff5a)
---
 sys/netgraph/ng_base.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sys/netgraph/ng_base.c b/sys/netgraph/ng_base.c
index 63bc251f52f9..ae179cf13a45 100644
--- a/sys/netgraph/ng_base.c
+++ b/sys/netgraph/ng_base.c
@@ -855,6 +855,10 @@ ng_name_node(node_p node, const char *name)
 	node_p node2;
 	int i;
 
+	/* Rename without change is a noop */
+	if (strcmp(NG_NODE_NAME(node), name) == 0)
+		return (0);
+
 	/* Check the name is valid */
 	for (i = 0; i < NG_NODESIZ; i++) {
 		if (name[i] == '\0' || name[i] == '.' || name[i] == ':')