wireguard: selftests: test multiple parallel streams

In order to test ndo_start_xmit being called in parallel, explicitly add
separate tests, which should all run on different cores. This should
help tease out bugs associated with queueing up packets from different
cores in parallel. Currently, it hasn't found those types of bugs, but
given future planned work, this is a useful regression to avoid.

Fixes: e7096c13 ("net: WireGuard secure network tunnel")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/wireguard/netns.sh

@@ -39,7 +39,7 @@ ip0() { pretty 0 "ip $*"; ip -n $netns0 "$@"; }
 ip1() { pretty 1 "ip $*"; ip -n $netns1 "$@"; }
 ip2() { pretty 2 "ip $*"; ip -n $netns2 "$@"; }
 sleep() { read -t "$1" -N 1 || true; }
-waitiperf() { pretty "${1//*-}" "wait for iperf:5201 pid $2"; while [[ $(ss -N "$1" -tlpH 'sport = 5201') != *\"iperf3\",pid=$2,fd=* ]]; do sleep 0.1; done; }
+waitiperf() { pretty "${1//*-}" "wait for iperf:${3:-5201} pid $2"; while [[ $(ss -N "$1" -tlpH "sport = ${3:-5201}") != *\"iperf3\",pid=$2,fd=* ]]; do sleep 0.1; done; }
 waitncatudp() { pretty "${1//*-}" "wait for udp:1111 pid $2"; while [[ $(ss -N "$1" -ulpH 'sport = 1111') != *\"ncat\",pid=$2,fd=* ]]; do sleep 0.1; done; }
 waitiface() { pretty "${1//*-}" "wait for $2 to come up"; ip netns exec "$1" bash -c "while [[ \$(< \"/sys/class/net/$2/operstate\") != up ]]; do read -t .1 -N 0 || true; done;"; }
 
@@ -141,6 +141,19 @@ tests() {
 	n2 iperf3 -s -1 -B fd00::2 &
 	waitiperf $netns2 $!
 	n1 iperf3 -Z -t 3 -b 0 -u -c fd00::2
+
+	# TCP over IPv4, in parallel
+	for max in 4 5 50; do
+		local pids=( )
+		for ((i=0; i < max; ++i)) do
+			n2 iperf3 -p $(( 5200 + i )) -s -1 -B 192.168.241.2 &
+			pids+=( $! ); waitiperf $netns2 $! $(( 5200 + i ))
+		done
+		for ((i=0; i < max; ++i)) do
+			n1 iperf3 -Z -t 3 -p $(( 5200 + i )) -c 192.168.241.2 &
+		done
+		wait "${pids[@]}"
+	done
 }
 
 [[ $(ip1 link show dev wg0) =~ mtu\ ([0-9]+) ]] && orig_mtu="${BASH_REMATCH[1]}"