Add support for the IFLA_BR_STP_MODE bridge attribute that allows
userspace to explicitly select the STP mode:
- auto (0): default, try /sbin/bridge-stp helper in init_net
- user (1): directly enable userspace STP without the helper,
works in any network namespace
- kernel (2): directly enable kernel STP without the helper
A shared file-scope stp_modes[] table indexed by BR_STP_MODE_* drives
both directions: parsing uses parse_one_of(), printing goes through a
stp_mode_to_str() helper that returns "(unknown)" for modes not yet
known to iproute2, keeping the JSON type of stp_mode consistently a
string.
Example usage:
ip link set br0 type bridge stp_mode user
ip link set br0 type bridge stp_state 1
Link:
https://lore.kernel.org/netdev/[email protected]/
Assisted-by: Claude:claude-opus-4-7
Reviewed-by: Ido Schimmel <[email protected]>
Signed-off-by: Andy Roulin <[email protected]>
---
Notes:
v2:
* Use a single file-scope stp_modes[] table indexed by
BR_STP_MODE_* for both parse and show, instead of an ad-hoc
strcmp ladder in parse and a separate local table in show
(David Ahern).
* Switch parsing to the shared parse_one_of() helper. Drop the
fallback that accepted numeric values on the parse side.
* Print path always returns a string: keep the JSON type of
stp_mode stable and fall back to "(unknown)" for unrecognized
values via a stp_mode_to_str() helper matching the style of
validate_to_str() in ip/ipmacsec.c (Ido Schimmel).
v1:
https://lore.kernel.org/netdev/[email protected]/
ip/iplink_bridge.c | 33 +++++++++++++++++++++++++++++++++
man/man8/ip-link.8.in | 32 ++++++++++++++++++++++++++++++++
2 files changed, 65 insertions(+)
diff --git a/ip/iplink_bridge.c b/ip/iplink_bridge.c
index df3264c3..1ae0501a 100644
--- a/ip/iplink_bridge.c
+++ b/ip/iplink_bridge.c
@@ -19,6 +19,20 @@
#include "utils.h"
#include "ip_common.h"
+static const char * const stp_modes[] = {
+ [BR_STP_MODE_AUTO] = "auto",
+ [BR_STP_MODE_USER] = "user",
+ [BR_STP_MODE_KERNEL] = "kernel",
+};
+
+static const char *stp_mode_to_str(__u32 mode)
+{
+ if (mode >= ARRAY_SIZE(stp_modes) || !stp_modes[mode])
+ return "(unknown)";
+
+ return stp_modes[mode];
+}
+
static unsigned int xstats_print_attr;
static int filter_index;
@@ -31,6 +45,7 @@ static void print_explain(FILE *f)
" [ max_age MAX_AGE ]\n"
" [ ageing_time AGEING_TIME ]\n"
" [ stp_state STP_STATE ]\n"
+ " [ stp_mode STP_MODE ]\n"
" [ mst_enabled MST_ENABLED ]\n"
" [ priority PRIORITY ]\n"
" [ group_fwd_mask MASK ]\n"
@@ -67,6 +82,7 @@ static void print_explain(FILE *f)
" [ mdb_offload_fail_notification
MDB_OFFLOAD_FAIL_NOTIFICATION ]\n"
"\n"
"Where: VLAN_PROTOCOL := { 802.1Q | 802.1ad }\n"
+ " STP_MODE := { auto | user | kernel }\n"
);
}
@@ -120,6 +136,16 @@ static int bridge_parse_opt(struct link_util *lu, int
argc, char **argv,
invarg("invalid stp_state", *argv);
addattr32(n, 1024, IFLA_BR_STP_STATE, val);
+ } else if (strcmp(*argv, "stp_mode") == 0) {
+ __u32 stp_mode;
+ int err;
+
+ NEXT_ARG();
+ stp_mode = parse_one_of("stp_mode", *argv, stp_modes,
+ ARRAY_SIZE(stp_modes), &err);
+ if (err)
+ return err;
+ addattr32(n, 1024, IFLA_BR_STP_MODE, stp_mode);
} else if (matches(*argv, "priority") == 0) {
__u16 prio;
@@ -512,6 +538,13 @@ static void bridge_print_opt(struct link_util *lu, FILE
*f, struct rtattr *tb[])
"stp_state %u ",
rta_getattr_u32(tb[IFLA_BR_STP_STATE]));
+ if (tb[IFLA_BR_STP_MODE]) {
+ __u32 mode = rta_getattr_u32(tb[IFLA_BR_STP_MODE]);
+
+ print_string(PRINT_ANY, "stp_mode", "stp_mode %s ",
+ stp_mode_to_str(mode));
+ }
+
if (tb[IFLA_BR_PRIORITY])
print_uint(PRINT_ANY,
"priority",
diff --git a/man/man8/ip-link.8.in b/man/man8/ip-link.8.in
index e89b2db3..b2661bdc 100644
--- a/man/man8/ip-link.8.in
+++ b/man/man8/ip-link.8.in
@@ -1719,6 +1719,8 @@ the following additional arguments are supported:
] [
.BI stp_state " STP_STATE "
] [
+.BI stp_mode " STP_MODE "
+] [
.BI mst_enabled " MST_ENABLED "
] [
.BI priority " PRIORITY "
@@ -1828,6 +1830,36 @@ or off
.RI ( STP_STATE " == 0). "
for this bridge.
+.BI stp_mode " STP_MODE "
+- set the STP mode for this bridge. This controls how the bridge
+selects between userspace and kernel STP when STP is enabled via
+.BR stp_state .
+.I STP_MODE
+can be one of:
+.in +8
+.sp
+.B auto
+(default) - invoke the
+.B /sbin/bridge-stp
+helper to hand the bridge to a userspace STP daemon. Only attempted in
+the initial network namespace; in other namespaces this falls back to
+kernel STP.
+
+.B user
+- directly enable userspace STP without invoking the helper. Works in
+any network namespace. The caller is responsible for registering the
+bridge with the userspace STP daemon.
+
+.B kernel
+- directly enable kernel STP without invoking the helper.
+.in -8
+
+Can only be changed while STP is disabled. Both
+.B stp_mode
+and
+.B stp_state
+can be set in a single command.
+
.BI mst_enabled " MST_ENABLED "
- turn multiple spanning tree (MST) support on
.RI ( MST_ENABLED " > 0) "
--
2.43.0
