[pve-devel] [PATCH common 1/2] fix #2831: never set bridge_fd to 0 with STP on

["Fabian Grünbichler" <f.gruenbichler@proxmox.com>]

it's an invalid combination that causes the network reload/setup to
fail. unfortunately, this is not caught by ifupdown2 itself, but only
rejected by the kernel with ERANGE over netlink.

Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
---

Notes:
    these range checks are there in the kernel since 2011..

 src/PVE/INotify.pm | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/PVE/INotify.pm b/src/PVE/INotify.pm
index 8cf4b44..4f682be 100644
--- a/src/PVE/INotify.pm
+++ b/src/PVE/INotify.pm
@@ -1061,13 +1061,12 @@ sub __read_etc_network_interfaces {
 	} elsif ($iface =~ m/^vmbr\d+$/) {
 	    if (!$d->{ovs_type}) {
 		$d->{type} = 'bridge';
-
-		if (!defined ($d->{bridge_fd})) {
-		    $d->{bridge_fd} = 0;
-		}
 		if (!defined ($d->{bridge_stp})) {
 		    $d->{bridge_stp} = 'off';
 		}
+		if (!defined($d->{bridge_fd}) && $d->{bridge_stp} eq 'off') {
+		    $d->{bridge_fd} = 0;
+		}
 	    } elsif ($d->{ovs_type} eq 'OVSBridge') {
 		$d->{type} = $d->{ovs_type};
 	    }
@@ -1259,11 +1258,16 @@ sub __interface_to_string {
 	$done->{bridge_ports} = 1;
 
 	my $v = defined($d->{bridge_stp}) ? $d->{bridge_stp} : 'off';
+	my $no_stp = $v eq 'off';
+
 	$raw .= "\tbridge-stp $v\n";
 	$done->{bridge_stp} = 1;
 
 	$v = defined($d->{bridge_fd}) ? $d->{bridge_fd} : 0;
-	$raw .= "\tbridge-fd $v\n";
+	# 0 is only allowed when STP is disabled
+	if ($v || $no_stp) {
+	    $raw .= "\tbridge-fd $v\n";
+	}
 	$done->{bridge_fd} = 1;
 
 	if( defined($d->{bridge_vlan_aware})) {
-- 
2.30.2