[PATCH net v2 0/2] net: netdevsim: fix inconsistent carrier state after link/unlink

[PATCH net v2 0/2] net: netdevsim: fix inconsistent carrier state after link/unlink

[yk]

From: Yohei Kojima <yk@y-koj.net>

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
=========
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                   |  6 ++
 .../selftests/drivers/net/netdevsim/peer.sh   | 63 +++++++++++++++++++
 2 files changed, 69 insertions(+)

-- 
2.51.2

[PATCH net v2 2/2] selftests: netdevsim: add carrier state consistency test

[yk]

From: Yohei Kojima <yk@y-koj.net>

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   | 63 +++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/tools/testing/selftests/drivers/net/netdevsim/peer.sh b/tools/testing/selftests/drivers/net/netdevsim/peer.sh
index 7f32b5600925..4ca994d2aa31 100755
--- a/tools/testing/selftests/drivers/net/netdevsim/peer.sh
+++ b/tools/testing/selftests/drivers/net/netdevsim/peer.sh
@@ -52,6 +52,43 @@ cleanup_ns()
 	ip netns del nssv
 }
 
+is_carrier_up()
+{
+	local netns="$1"
+	local nsim_dev="$2"
+
+	# 0: DOWN
+	# 1: UP
+	local is_up=$(ip netns exec "$netns"	\
+		cat /sys/class/net/"$nsim_dev"/carrier 2>/dev/null)
+
+	test "$is_up" -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 +150,32 @@ 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)
-- 
2.51.2