Add a selftest for the IFLA_BR_STP_MODE bridge attribute that verifies: 1. stp_mode defaults to auto on new bridges 2. stp_mode can be toggled between user, kernel, and auto 3. Changing stp_mode while STP is active is rejected with -EBUSY 4. stp_mode user in a network namespace yields userspace STP (stp_state=2) 5. stp_mode kernel forces kernel STP (stp_state=1) 6. stp_mode auto in a netns preserves traditional fallback to kernel STP 7. stp_mode and stp_state can be set atomically in a single message 8. stp_mode persists across STP disable/enable cycles
Test 4 is the key use case: it demonstrates that userspace STP can now be enabled in non-init network namespaces by setting stp_mode to user before enabling STP. Test 7 verifies the atomic usage pattern where both attributes are set in a single netlink message, which is supported because br_changelink() processes IFLA_BR_STP_MODE before IFLA_BR_STP_STATE. The test gracefully skips if the installed iproute2 does not support the stp_mode attribute. Reviewed-by: Ido Schimmel <[email protected]> Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Andy Roulin <[email protected]> --- tools/testing/selftests/net/Makefile | 1 + .../testing/selftests/net/bridge_stp_mode.sh | 261 ++++++++++++++++++ 2 files changed, 262 insertions(+) create mode 100755 tools/testing/selftests/net/bridge_stp_mode.sh diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile index 6bced3ed798b0..053c7b83c76dd 100644 --- a/tools/testing/selftests/net/Makefile +++ b/tools/testing/selftests/net/Makefile @@ -15,6 +15,7 @@ TEST_PROGS := \ big_tcp.sh \ bind_bhash.sh \ bpf_offload.py \ + bridge_stp_mode.sh \ bridge_vlan_dump.sh \ broadcast_ether_dst.sh \ broadcast_pmtu.sh \ diff --git a/tools/testing/selftests/net/bridge_stp_mode.sh b/tools/testing/selftests/net/bridge_stp_mode.sh new file mode 100755 index 0000000000000..9c99d5b6fd667 --- /dev/null +++ b/tools/testing/selftests/net/bridge_stp_mode.sh @@ -0,0 +1,261 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# shellcheck disable=SC2034,SC2154,SC2317 +# +# Test for bridge STP mode selection (IFLA_BR_STP_MODE). +# +# Verifies that: +# - stp_mode defaults to auto on new bridges +# - stp_mode can be toggled between user, kernel, and auto +# - stp_mode change is rejected while STP is active (-EBUSY) +# - stp_mode user in a netns yields userspace STP (stp_state=2) +# - stp_mode kernel forces kernel STP (stp_state=1) +# - stp_mode auto preserves traditional fallback to kernel STP +# - stp_mode and stp_state can be set atomically in one message +# - stp_mode persists across STP disable/enable cycles + +source lib.sh + +require_command jq + +ALL_TESTS=" + test_default_auto + test_set_modes + test_reject_change_while_stp_active + test_user_mode_in_netns + test_kernel_mode + test_auto_mode + test_atomic_mode_and_state + test_mode_persistence +" + +bridge_info_get() +{ + ip -n "$NS1" -d -j link show "$1" | \ + jq -r ".[0].linkinfo.info_data.$2" +} + +check_stp_mode() +{ + local br=$1; shift + local expected=$1; shift + local msg=$1; shift + local val + + val=$(bridge_info_get "$br" stp_mode) + [ "$val" = "$expected" ] + check_err $? "$msg: expected $expected, got $val" +} + +check_stp_state() +{ + local br=$1; shift + local expected=$1; shift + local msg=$1; shift + local val + + val=$(bridge_info_get "$br" stp_state) + [ "$val" = "$expected" ] + check_err $? "$msg: expected $expected, got $val" +} + +# Create a bridge in NS1, bring it up, and defer its deletion. +bridge_create() +{ + ip -n "$NS1" link add "$1" type bridge + ip -n "$NS1" link set "$1" up + defer ip -n "$NS1" link del "$1" +} + +setup_prepare() +{ + setup_ns NS1 +} + +cleanup() +{ + defer_scopes_cleanup + cleanup_all_ns +} + +# Check that stp_mode defaults to auto when creating a bridge. +test_default_auto() +{ + RET=0 + + ip -n "$NS1" link add br-test type bridge + defer ip -n "$NS1" link del br-test + + check_stp_mode br-test auto "stp_mode default" + + log_test "stp_mode defaults to auto" +} + +# Test setting stp_mode to user, kernel, and back to auto. +test_set_modes() +{ + RET=0 + + ip -n "$NS1" link add br-test type bridge + defer ip -n "$NS1" link del br-test + + ip -n "$NS1" link set dev br-test type bridge stp_mode user + check_err $? "Failed to set stp_mode to user" + check_stp_mode br-test user "after set user" + + ip -n "$NS1" link set dev br-test type bridge stp_mode kernel + check_err $? "Failed to set stp_mode to kernel" + check_stp_mode br-test kernel "after set kernel" + + ip -n "$NS1" link set dev br-test type bridge stp_mode auto + check_err $? "Failed to set stp_mode to auto" + check_stp_mode br-test auto "after set auto" + + log_test "stp_mode set user/kernel/auto" +} + +# Verify that stp_mode cannot be changed while STP is active. +test_reject_change_while_stp_active() +{ + RET=0 + + bridge_create br-test + + ip -n "$NS1" link set dev br-test type bridge stp_mode kernel + check_err $? "Failed to set stp_mode to kernel" + + ip -n "$NS1" link set dev br-test type bridge stp_state 1 + check_err $? "Failed to enable STP" + + # Changing stp_mode while STP is active should fail. + ip -n "$NS1" link set dev br-test type bridge stp_mode auto 2>/dev/null + check_fail $? "Changing stp_mode should fail while STP is active" + + check_stp_mode br-test kernel "mode unchanged after rejected change" + + # Disable STP, then change should succeed. + ip -n "$NS1" link set dev br-test type bridge stp_state 0 + check_err $? "Failed to disable STP" + + ip -n "$NS1" link set dev br-test type bridge stp_mode auto + check_err $? "Changing stp_mode should succeed after STP is disabled" + + log_test "reject stp_mode change while STP is active" +} + +# Test that stp_mode user in a non-init netns yields userspace STP +# (stp_state == 2). This is the key use case: userspace STP without +# needing /sbin/bridge-stp or being in init_net. +test_user_mode_in_netns() +{ + RET=0 + + bridge_create br-test + + ip -n "$NS1" link set dev br-test type bridge stp_mode user + check_err $? "Failed to set stp_mode to user" + + ip -n "$NS1" link set dev br-test type bridge stp_state 1 + check_err $? "Failed to enable STP" + + check_stp_state br-test 2 "stp_state with user mode" + + log_test "stp_mode user in netns yields userspace STP" +} + +# Test that stp_mode kernel forces kernel STP (stp_state == 1) +# regardless of whether /sbin/bridge-stp exists. +test_kernel_mode() +{ + RET=0 + + bridge_create br-test + + ip -n "$NS1" link set dev br-test type bridge stp_mode kernel + check_err $? "Failed to set stp_mode to kernel" + + ip -n "$NS1" link set dev br-test type bridge stp_state 1 + check_err $? "Failed to enable STP" + + check_stp_state br-test 1 "stp_state with kernel mode" + + log_test "stp_mode kernel forces kernel STP" +} + +# Test that stp_mode auto preserves traditional behavior: in a netns +# (non-init_net), bridge-stp is not called and STP falls back to +# kernel mode (stp_state == 1). +test_auto_mode() +{ + RET=0 + + bridge_create br-test + + # Auto mode is the default; enable STP in a netns. + ip -n "$NS1" link set dev br-test type bridge stp_state 1 + check_err $? "Failed to enable STP" + + # In a netns with auto mode, bridge-stp is skipped (init_net only), + # so STP should fall back to kernel mode (stp_state == 1). + check_stp_state br-test 1 "stp_state with auto mode in netns" + + log_test "stp_mode auto preserves traditional behavior" +} + +# Test that stp_mode and stp_state can be set in a single netlink +# message. This is the intended atomic usage pattern. +test_atomic_mode_and_state() +{ + RET=0 + + bridge_create br-test + + # Set both stp_mode and stp_state in one command. + ip -n "$NS1" link set dev br-test type bridge stp_mode user stp_state 1 + check_err $? "Failed to set stp_mode user and stp_state 1 atomically" + + check_stp_state br-test 2 "stp_state after atomic set" + + log_test "atomic stp_mode user + stp_state 1 in single message" +} + +# Test that stp_mode persists across STP disable/enable cycles. +test_mode_persistence() +{ + RET=0 + + bridge_create br-test + + # Set user mode and enable STP. + ip -n "$NS1" link set dev br-test type bridge stp_mode user + ip -n "$NS1" link set dev br-test type bridge stp_state 1 + check_err $? "Failed to enable STP with user mode" + + # Disable STP. + ip -n "$NS1" link set dev br-test type bridge stp_state 0 + check_err $? "Failed to disable STP" + + # Verify mode is still user. + check_stp_mode br-test user "stp_mode after STP disable" + + # Re-enable STP -- should use user mode again. + ip -n "$NS1" link set dev br-test type bridge stp_state 1 + check_err $? "Failed to re-enable STP" + + check_stp_state br-test 2 "stp_state after re-enable" + + log_test "stp_mode persists across STP disable/enable cycles" +} + +# Check iproute2 support before setting up resources. +if ! ip link add type bridge help 2>&1 | grep -q "stp_mode"; then + echo "SKIP: iproute2 too old, missing stp_mode support" + exit "$ksft_skip" +fi + +trap cleanup EXIT + +setup_prepare +tests_run + +exit "$EXIT_STATUS" -- 2.43.0
