[PATCH mptcp-next 1/4] selftests: mptcp: join: properly kill background tasks

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

The 'run_tests' function is executed in the background, but killing its
associated PID would not kill the children tasks running in the
background.

To properly kill all background tasks, 'kill -- -PID' could be used, but
this requires kill from procps-ng. Instead, all children tasks are
listed using 'ps', and 'kill' is called with all PIDs of this group.

Fixes: 31ee4ad86afd ("selftests: mptcp: join: stop transfer when check is done (part 1)")
Fixes: 04b57c9e096a ("selftests: mptcp: join: stop transfer when check is done (part 2)")
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 tools/testing/selftests/net/mptcp/mptcp_join.sh | 18 +++++++++---------
 tools/testing/selftests/net/mptcp/mptcp_lib.sh  | 21 +++++++++++++++++++++
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 6afcf6ad2788..8be8bfa71946 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -3995,7 +3995,7 @@ userspace_tests()
 		chk_mptcp_info subflows 0 subflows 0
 		chk_subflows_total 1 1
 		kill_events_pids
-		mptcp_lib_kill_wait $tests_pid
+		mptcp_lib_kill_group_wait $tests_pid
 	fi
 
 	# userspace pm create destroy subflow
@@ -4023,7 +4023,7 @@ userspace_tests()
 		chk_mptcp_info subflows 0 subflows 0
 		chk_subflows_total 1 1
 		kill_events_pids
-		mptcp_lib_kill_wait $tests_pid
+		mptcp_lib_kill_group_wait $tests_pid
 	fi
 
 	# userspace pm create id 0 subflow
@@ -4044,7 +4044,7 @@ userspace_tests()
 		chk_mptcp_info subflows 1 subflows 1
 		chk_subflows_total 2 2
 		kill_events_pids
-		mptcp_lib_kill_wait $tests_pid
+		mptcp_lib_kill_group_wait $tests_pid
 	fi
 
 	# userspace pm remove initial subflow
@@ -4068,7 +4068,7 @@ userspace_tests()
 		chk_mptcp_info subflows 1 subflows 1
 		chk_subflows_total 1 1
 		kill_events_pids
-		mptcp_lib_kill_wait $tests_pid
+		mptcp_lib_kill_group_wait $tests_pid
 	fi
 
 	# userspace pm send RM_ADDR for ID 0
@@ -4094,7 +4094,7 @@ userspace_tests()
 		chk_mptcp_info subflows 1 subflows 1
 		chk_subflows_total 1 1
 		kill_events_pids
-		mptcp_lib_kill_wait $tests_pid
+		mptcp_lib_kill_group_wait $tests_pid
 	fi
 }
 
@@ -4124,7 +4124,7 @@ endpoint_tests()
 		pm_nl_add_endpoint $ns2 10.0.2.2 flags signal
 		pm_nl_check_endpoint "modif is allowed" \
 			$ns2 10.0.2.2 id 1 flags signal
-		mptcp_lib_kill_wait $tests_pid
+		mptcp_lib_kill_group_wait $tests_pid
 	fi
 
 	if reset_with_tcp_filter "delete and re-add" ns2 10.0.3.2 REJECT OUTPUT &&
@@ -4179,7 +4179,7 @@ endpoint_tests()
 			chk_mptcp_info subflows 3 subflows 3
 		done
 
-		mptcp_lib_kill_wait $tests_pid
+		mptcp_lib_kill_group_wait $tests_pid
 
 		kill_events_pids
 		chk_evt_nr ns1 MPTCP_LIB_EVENT_LISTENER_CREATED 1
@@ -4253,7 +4253,7 @@ endpoint_tests()
 		wait_mpj $ns2
 		chk_subflow_nr "after re-re-add ID 0" 3
 		chk_mptcp_info subflows 3 subflows 3
-		mptcp_lib_kill_wait $tests_pid
+		mptcp_lib_kill_group_wait $tests_pid
 
 		kill_events_pids
 		chk_evt_nr ns1 MPTCP_LIB_EVENT_LISTENER_CREATED 1
@@ -4301,7 +4301,7 @@ endpoint_tests()
 		wait_mpj $ns2
 		pm_nl_add_endpoint $ns1 10.0.3.1 id 2 flags signal
 		wait_mpj $ns2
-		mptcp_lib_kill_wait $tests_pid
+		mptcp_lib_kill_group_wait $tests_pid
 
 		join_syn_tx=3 join_connect_err=1 \
 			chk_join_nr 2 2 2
diff --git a/tools/testing/selftests/net/mptcp/mptcp_lib.sh b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
index ce6c92826be7..91ec75ddcb96 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_lib.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
@@ -359,6 +359,27 @@ mptcp_lib_kill_wait() {
 	wait "${1}" 2>/dev/null
 }
 
+# $1: PID
+mptcp_lib_pid_list_children() {
+	local curr="${1}"
+	# evoke 'ps' only once
+	local pids="${2:-"$(ps o pid,ppid)"}"
+
+	echo "${curr}"
+
+	local pid
+	for pid in $(echo "${pids}" | awk "\$2 == ${curr} { print \$1 }"); do
+		mptcp_lib_pid_list_children "${pid}" "${pids}"
+	done
+}
+
+# $1: PID
+mptcp_lib_kill_group_wait() {
+	# Some users might not have procps-ng: cannot use "kill -- -PID"
+	mptcp_lib_pid_list_children "${1}" | xargs -r kill &>/dev/null
+	wait "${1}" 2>/dev/null
+}
+
 # $1: IP address
 mptcp_lib_is_v6() {
 	[ -z "${1##*:*}" ]

-- 
2.51.0