[PATCH mptcp-next v6 7/9] selftests: net: lib: remove 'ns' var in setup_ns

["Matthieu Baerts (NGI0)" <matttbe@kernel.org>]

From: Geliang Tang <tanggeliang@kylinos.cn>

The helper setup_ns() doesn't work when a net namespace named "ns" is
passed to it.

For example, in net/mptcp/diag.sh, the name of the namespace is "ns". If
"setup_ns ns" is used in it, diag.sh fails with errors:

  Invalid netns name "./mptcp_connect"
  Cannot open network namespace "10000": No such file or directory
  Cannot open network namespace "10000": No such file or directory

That is because "ns" is also a local variable in setup_ns, and it will
not set the value for the global variable that has been giving in
argument. To solve this, we could rename the variable, but it sounds
better to drop it, as we can resolve the name using the variable passed
in argument instead.

The other local variables -- "ns_list" and "ns_name" -- are more
unlikely to conflict with existing global variables. They don't seem to
be currently used in other net selftests.

Co-developed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 tools/testing/selftests/net/lib.sh | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/net/lib.sh b/tools/testing/selftests/net/lib.sh
index 114b927fee25..915f319bcc8b 100644
--- a/tools/testing/selftests/net/lib.sh
+++ b/tools/testing/selftests/net/lib.sh
@@ -167,26 +167,30 @@ cleanup_all_ns()
 # setup_ns local remote
 setup_ns()
 {
-	local ns=""
 	local ns_name=""
 	local ns_list=()
 	for ns_name in "$@"; do
-		# Some test may setup/remove same netns multi times
-		if [ -z "${!ns_name}" ]; then
-			ns="${ns_name,,}-$(mktemp -u XXXXXX)"
-			eval "${ns_name}=${ns}"
-		else
-			ns="${!ns_name}"
-			cleanup_ns "$ns"
+		# avoid conflicts with local var: internal error
+		if [ "${ns_name}" = "ns_name" ]; then
+			echo "Failed to setup namespace '${ns_name}': invalid name"
+			cleanup_ns "${ns_list[@]}"
+			exit $ksft_fail
 		fi
 
-		if ! ip netns add "$ns"; then
+		# Some test may setup/remove same netns multi times
+		if [ -z "${!ns_name}" ]; then
+			eval "${ns_name}=${ns_name,,}-$(mktemp -u XXXXXX)"
+		else
+			cleanup_ns "${!ns_name}"
+		fi
+
+		if ! ip netns add "${!ns_name}"; then
 			echo "Failed to create namespace $ns_name"
 			cleanup_ns "${ns_list[@]}"
 			return $ksft_skip
 		fi
-		ip -n "$ns" link set lo up
-		ns_list+=("$ns")
+		ip -n "${!ns_name}" link set lo up
+		ns_list+=("${!ns_name}")
 	done
 	NS_LIST+=("${ns_list[@]}")
 }

-- 
2.43.0