This series fixes netdevsim's inconsistent behavior between carrier and link/unlink state.
More specifically, this fixes a bug that the carrier goes DOWN although two netdevsim were peered, depending on the order of peering and ifup. Especially in a NetworkManager-enabled environment, netdevsim test fails because of this.
The first patch fixes the bug itself in netdevsim/bus.c by adding netif_carrier_on() into a proper function. The second patch adds a regression test for this bug.
Changelog ========= v2 -> v3: - Rebase to the latest net/main - patch 1: - Add Reviewed-by tag from Breno Leitao - Address the review comments from Jakub Kicinski regarding the condition to call netif_carrier_on() - patch 2: - Solve the shellcheck warning in the test - Line too long error is left as is for consistency with other test cases - v2: https://lore.kernel.org/netdev/cover.1767108538.git.yk@y-koj.net/
v1 -> v2: - Rebase to the latest net/main - Separate TFO tests from this series - Separate netdevsim test improvement from this series - v1: https://lore.kernel.org/netdev/cover.1767032397.git.yk@y-koj.net/
Yohei Kojima (2): net: netdevsim: fix inconsistent carrier state after link/unlink selftests: netdevsim: add carrier state consistency test
drivers/net/netdevsim/bus.c | 8 +++ .../selftests/drivers/net/netdevsim/peer.sh | 59 +++++++++++++++++++ 2 files changed, 67 insertions(+)
This commit adds a test case for netdevsim carrier state consistency. Specifically, the added test verifies the carrier state during the following operations:
1. Unlink two netdevsims 2. ifdown one netdevsim, then ifup again 3. Link the netdevsims again 4. ifdown one netdevsim, then ifup again
These steps verifies that the carrier is UP iff two netdevsims are linked and ifuped.
Signed-off-by: Yohei Kojima yk@y-koj.net --- .../selftests/drivers/net/netdevsim/peer.sh | 59 +++++++++++++++++++ 1 file changed, 59 insertions(+)
diff --git a/tools/testing/selftests/drivers/net/netdevsim/peer.sh b/tools/testing/selftests/drivers/net/netdevsim/peer.sh index 7f32b5600925..f4721f7636dd 100755 --- a/tools/testing/selftests/drivers/net/netdevsim/peer.sh +++ b/tools/testing/selftests/drivers/net/netdevsim/peer.sh @@ -52,6 +52,39 @@ cleanup_ns() ip netns del nssv }
+is_carrier_up() +{ + local netns="$1" + local nsim_dev="$2" + + test "$(ip netns exec "$netns" \ + cat /sys/class/net/"$nsim_dev"/carrier 2>/dev/null)" -eq 1 +} + +assert_carrier_up() +{ + local netns="$1" + local nsim_dev="$2" + + if ! is_carrier_up "$netns" "$nsim_dev"; then + echo "$nsim_dev's carrier should be UP, but it isn't" + cleanup_ns + exit 1 + fi +} + +assert_carrier_down() +{ + local netns="$1" + local nsim_dev="$2" + + if is_carrier_up "$netns" "$nsim_dev"; then + echo "$nsim_dev's carrier should be DOWN, but it isn't" + cleanup_ns + exit 1 + fi +} + ### ### Code start ### @@ -113,6 +146,32 @@ if [ $? -eq 0 ]; then exit 1 fi
+# netdevsim carrier state consistency checking +assert_carrier_up nssv "$NSIM_DEV_1_NAME" +assert_carrier_up nscl "$NSIM_DEV_2_NAME" + +echo "$NSIM_DEV_1_FD:$NSIM_DEV_1_IFIDX" > "$NSIM_DEV_SYS_UNLINK" + +assert_carrier_down nssv "$NSIM_DEV_1_NAME" +assert_carrier_down nscl "$NSIM_DEV_2_NAME" + +ip netns exec nssv ip link set dev "$NSIM_DEV_1_NAME" down +ip netns exec nssv ip link set dev "$NSIM_DEV_1_NAME" up + +assert_carrier_down nssv "$NSIM_DEV_1_NAME" +assert_carrier_down nscl "$NSIM_DEV_2_NAME" + +echo "$NSIM_DEV_1_FD:$NSIM_DEV_1_IFIDX $NSIM_DEV_2_FD:$NSIM_DEV_2_IFIDX" > $NSIM_DEV_SYS_LINK + +assert_carrier_up nssv "$NSIM_DEV_1_NAME" +assert_carrier_up nscl "$NSIM_DEV_2_NAME" + +ip netns exec nssv ip link set dev "$NSIM_DEV_1_NAME" down +ip netns exec nssv ip link set dev "$NSIM_DEV_1_NAME" up + +assert_carrier_up nssv "$NSIM_DEV_1_NAME" +assert_carrier_up nscl "$NSIM_DEV_2_NAME" + # send/recv packets
tmp_file=$(mktemp)
Hello:
This series was applied to netdev/net.git (main) by Jakub Kicinski kuba@kernel.org:
On Tue, 6 Jan 2026 00:17:31 +0900 you wrote:
This series fixes netdevsim's inconsistent behavior between carrier and link/unlink state.
More specifically, this fixes a bug that the carrier goes DOWN although two netdevsim were peered, depending on the order of peering and ifup. Especially in a NetworkManager-enabled environment, netdevsim test fails because of this.
[...]
Here is the summary with links: - [net,v3,1/2] net: netdevsim: fix inconsistent carrier state after link/unlink https://git.kernel.org/netdev/net/c/d83dddffe190 - [net,v3,2/2] selftests: netdevsim: add carrier state consistency test https://git.kernel.org/netdev/net/c/75df712cddfd
You are awesome, thank you!
linux-kselftest-mirror@lists.linaro.org
-
patchwork-bot+netdevbpf＠kernel.org -
Yohei Kojima