[PATCH net v2 1/2] selftests/net: fix kill() argument order and wrapper cleanup in fin_ack_lat

[Qingshuang Fu]

From: Qingshuang Fu <fuqingshuang@xxxxxxxxxx>

sig_handler() passes its arguments to kill() in the wrong order: it sends
signal number child_pid to PID SIGTERM (15) instead of sending SIGTERM
to the client process.  The call therefore always fails and the signal
is never forwarded: when only the server process receives SIGTERM, the
client keeps running its infinite connect loop as an orphan process.

Swap the arguments so that the server forwards SIGTERM to the client.
Guard the call with child_pid > 0: the client inherits the handler and
sees child_pid == 0, and a plain argument swap would make it call
kill(0, SIGTERM), signaling the whole process group instead of exiting
quietly.

Now that the server actually terminates the client before the wrapper
script's cleanup runs, kill() may fail with ESRCH for the already-exited
client.  The script uses set -e, so make the kill tolerant to avoid
aborting the EXIT trap and leaking temporary files.

Fixes: af8c8a450bf4 ("selftests: net: Add FIN_ACK processing order related latency spike test")
Signed-off-by: Qingshuang Fu <fuqingshuang@xxxxxxxxxx>
---
 tools/testing/selftests/net/fin_ack_lat.c  | 3 ++-
 tools/testing/selftests/net/fin_ack_lat.sh | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/fin_ack_lat.c b/tools/testing/selftests/net/fin_ack_lat.c
index 4117332eb1a9..98044e6f9f43 100644
--- a/tools/testing/selftests/net/fin_ack_lat.c
+++ b/tools/testing/selftests/net/fin_ack_lat.c
@@ -103,7 +103,8 @@ static void server(int sock, struct sockaddr_in address)
 
 static void sig_handler(int signum)
 {
-	kill(SIGTERM, child_pid);
+	if (child_pid > 0)
+		kill(child_pid, SIGTERM);
 	exit(0);
 }
 
diff --git a/tools/testing/selftests/net/fin_ack_lat.sh b/tools/testing/selftests/net/fin_ack_lat.sh
index a3ff6e0b2c7a..a8aa2238ab5c 100755
--- a/tools/testing/selftests/net/fin_ack_lat.sh
+++ b/tools/testing/selftests/net/fin_ack_lat.sh
@@ -9,7 +9,7 @@ set -e
 tmpfile=$(mktemp /tmp/fin_ack_latency.XXXX.log)
 
 cleanup() {
-	kill $(pidof fin_ack_lat)
+	kill $(pidof fin_ack_lat) 2>/dev/null || true
 	rm -f $tmpfile
 }
 

base-commit: 7f063b2f17eaba2a35e251aa53627f2a70d536e2
-- 
2.25.1