Re: [PATCH rdma-next v3 14/14] RDMA/selftests: Add rxe_netns_names test

From: Jiri Pirko <redacted>

Add a kselftest script that exercises per-netns RDMA device naming
with RXE. Cover duplicate names across namespaces, move conflict
handling, move-with-rename, and same-namespace rename requests.

Signed-off-by: Jiri Pirko <redacted>
---
v2->v3:
- added wait for rdma devices are removed
- added retry for old rdma netns mode restore
v1->v2:
- fixed ktap_set_plan
- s/RXE_A/RXE_SAME/ in dup rename
---
  tools/testing/selftests/rdma/Makefile         |   3 +-
  tools/testing/selftests/rdma/config           |   2 +
  .../testing/selftests/rdma/rxe_netns_names.sh | 334 ++++++++++++++++++
  3 files changed, 338 insertions(+), 1 deletion(-)
  create mode 100755 tools/testing/selftests/rdma/rxe_netns_names.sh

diff --git a/tools/testing/selftests/rdma/Makefile b/tools/testing/selftests/rdma/Makefile
index 07af7f15c1bf..a91c14c45006 100644
--- a/tools/testing/selftests/rdma/Makefile
+++ b/tools/testing/selftests/rdma/Makefile

@@ -3,6 +3,7 @@ TEST_PROGS := rxe_rping_between_netns.sh \
  		rxe_ipv6.sh \
  		rxe_socket_with_netns.sh \
  		rxe_test_NETDEV_UNREGISTER.sh \
-		rxe_sent_rcvd_bytes.sh
+		rxe_sent_rcvd_bytes.sh \
+		rxe_netns_names.sh
  
  include ../lib.mk

diff --git a/tools/testing/selftests/rdma/config b/tools/testing/selftests/rdma/config
index 4ffb814e253b..e1ff54ec0f57 100644
--- a/tools/testing/selftests/rdma/config
+++ b/tools/testing/selftests/rdma/config

@@ -1,3 +1,5 @@
  CONFIG_TUN
  CONFIG_VETH
+CONFIG_DUMMY
+CONFIG_NET_NS
  CONFIG_RDMA_RXE

diff --git a/tools/testing/selftests/rdma/rxe_netns_names.sh b/tools/testing/selftests/rdma/rxe_netns_names.sh
new file mode 100755
index 000000000000..f40118407f4c
--- /dev/null
+++ b/tools/testing/selftests/rdma/rxe_netns_names.sh

@@ -0,0 +1,334 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Exercise RDMA device name handling across network namespaces.
+
+source "$(dirname "$0")/../kselftest/ktap_helpers.sh"
+
+NAME_PREFIX="rxe_netns_names_$$"
+NETDEV_PREFIX="rxn$$"
+NS1="${NAME_PREFIX}ns1"
+NS2="${NAME_PREFIX}ns2"
+RXE_A="${NAME_PREFIX}rxe_a"
+RXE_B="${NAME_PREFIX}rxe_b"
+RXE_SAME="${NAME_PREFIX}rxe_same"
+RXE_NEW="${NAME_PREFIX}rxe_new"
+DUMMY_A="${NETDEV_PREFIX}a"
+DUMMY_B="${NETDEV_PREFIX}b"
+OLD_MODE=""
+MODE_CHANGED=0
+MODS=("dummy" "rdma_rxe")
+TEST_SAME_NAMES="same RDMA device name can exist in two net namespaces"
+TEST_MOVE_CONFLICT="move without rename fails on destination name conflict"
+TEST_MOVE_RENAME="move then rename succeeds"
+TEST_COMBINED_MOVE_RENAME="move with requested destination name succeeds"
+TEST_SAME_NETNS_DUP_RENAME="same-netns rename rejects duplicate name"
+TEST_TEARDOWN_RETURN="netns delete returns device to init_net and renames on conflict"
+
+ksft_skip()
+{
+	ktap_skip_all "$*"
+	exit "$KSFT_SKIP"
+}
+
+fail()
+{
+	ktap_exit_fail_msg "$*"
+}
+
+need_cmd()
+{
+	command -v "$1" >/dev/null 2>&1 || ksft_skip "missing command: $1"
+}
+
+rdma_ns()
+{
+	local ns=$1
+
+	shift
+	ip netns exec "$ns" rdma "$@"
+}
+
+rdma_dev_exists()
+{
+	local ns=$1
+	local dev=$2
+
+	if [ -n "$ns" ]; then
+		rdma_ns "$ns" dev show "$dev" >/dev/null 2>&1
+	else
+		rdma dev show "$dev" >/dev/null 2>&1
+	fi
+}
+
+add_dummy()
+{
+	local netdev=$1
+
+	ip link add "$netdev" type dummy || return 1
+	ip link set "$netdev" up || return 1
+}
+
+add_rxe()
+{
+	local dev=$1
+	local netdev=$2
+
+	rdma link add "$dev" type rxe netdev "$netdev"
+}
+
+rdma_dev_on_netdev()
+{
+	local netdev=$1
+
+	rdma link show 2>/dev/null | awk -v want="$netdev" '
+		{
+			for (i = 1; i < NF; i++)
+				if ($i == "netdev" && $(i + 1) == want) {
+					dev = $2
+					sub(/\/.*/, "", dev)
+					print dev
+					exit
+				}
+		}'
+}
+
+wait_rdma_dev_on_netdev()
+{
+	local netdev=$1
+	local dev
+	local i
+
+	for i in $(seq 1 50); do
+		dev=$(rdma_dev_on_netdev "$netdev")
+		if [ -n "$dev" ]; then
+			echo "$dev"
+			return 0
+		fi
+		sleep 0.1
+	done
+
+	return 1
+}
+
+# ip link del returns after NETDEV_UNREGISTER, but rxe tears the RDMA device
+# down asynchronously via ib_unregister_device_queued(). Wait until our names
+# are gone.
+wait_rdma_devs_gone()
+{
+	local i name ns
+	local names=("$RXE_A" "$RXE_B" "$RXE_SAME" "$RXE_NEW")
+
+	for i in $(seq 1 50); do
+		local found=0
+
+		for name in "${names[@]}"; do
+			if rdma_dev_exists "" "$name"; then
+				found=1
+				break
+			fi
+			for ns in "$NS1" "$NS2"; do
+				ip netns exec "$ns" true 2>/dev/null || continue
+				if rdma_dev_exists "$ns" "$name"; then
+					found=1
+					break 2
+				fi
+			done
+		done
+
+		[ "$found" -eq 0 ] && return 0
+		sleep 0.1
+	done
+
+	return 1
+}
+
+setup_devs()
+{
+	cleanup_devs || return 1
+
+	add_dummy "$DUMMY_A" || return 1
+	add_dummy "$DUMMY_B" || return 1
+
+	add_rxe "$RXE_A" "$DUMMY_A" || return 1
+	add_rxe "$RXE_B" "$DUMMY_B" || return 1
+}
+
+cleanup_devs()
+{
+	ip link del "$DUMMY_A" 2>/dev/null
+	ip link del "$DUMMY_B" 2>/dev/null
+	wait_rdma_devs_gone
+}
+
+setup()
+{
+	OLD_MODE=$(rdma system show 2>/dev/null |
+		   sed -n 's/.*netns \([^ ]*\).*/\1/p')
+	[ -n "$OLD_MODE" ] || ksft_skip "failed to read RDMA netns mode"
+
+	rdma system set netns exclusive >/dev/null 2>&1 ||
+		ksft_skip "rdma netns exclusive mode is not supported"
+	MODE_CHANGED=1
+
+	ip netns add "$NS1" || return 1
+	ip netns add "$NS2" || return 1
+}
+
+# ip netns del returns before rdma_dev_exit_net() removes the net from
+# rdma_nets. rdma_compatdev_set() returns -EBUSY until that completes, so
+# retry the mode restore instead of leaving the system in exclusive mode.
+restore_netns_mode()
+{
+	local i
+
+	[ "$MODE_CHANGED" -eq 1 ] || return 0
+
+	for i in $(seq 1 50); do
+		if rdma system set netns "$OLD_MODE" >/dev/null 2>&1; then
+			MODE_CHANGED=0
+			return 0
+		fi
+		sleep 0.1
+	done
+
+	echo "warning: failed to restore RDMA netns mode to $OLD_MODE" >&2
+	return 1
+}
+
+cleanup()
+{
+	cleanup_devs
+
+	ip netns del "$NS1" 2>/dev/null
+	ip netns del "$NS2" 2>/dev/null
+
+	restore_netns_mode
+
+	for m in "${MODS[@]}"; do
+		modprobe -r "$m" 2>/dev/null
+	done
+}
+
+rdma_supports_combined_move_rename()
+{
+	rdma dev help 2>&1 | grep -Eq 'netns .*name|name .*netns'
+}
+
+[ "$(id -u)" -eq 0 ] || ksft_skip "must be run as root"
+need_cmd ip
+need_cmd rdma
+need_cmd modprobe
+
+trap cleanup EXIT
+
+for m in "${MODS[@]}"; do
+	modinfo "$m" >/dev/null 2>&1 || ksft_skip "module $m not found"
+	modprobe "$m" || fail "failed to load $m"
+done
+
+setup || fail "failed to create net namespaces"
+
+ktap_print_header
+ktap_set_plan 6