selftest/rxe: Add selftests for perf

Create a virtual TUN net device with RXE support, then run rping
server and client to invoke networking packets, finally compare both
*port_xmit_data* and *port_rcv_data* of such device.

Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Link: https://patch.msgid.link/20260414062948.671658-5-zhenwei.pi@linux.dev
Signed-off-by: Leon Romanovsky <leon@kernel.org>

tools/testing/selftests/rdma/Makefile

@@ -2,6 +2,7 @@
 TEST_PROGS := rxe_rping_between_netns.sh \
 		rxe_ipv6.sh \
 		rxe_socket_with_netns.sh \
-		rxe_test_NETDEV_UNREGISTER.sh
+		rxe_test_NETDEV_UNREGISTER.sh \
+		rxe_sent_rcvd_bytes.sh
 
 include ../lib.mk

tools/testing/selftests/rdma/rxe_sent_rcvd_bytes.sh

@@ -0,0 +1,75 @@
+#!/bin/bash
+
+# Configuration
+PORT=4791
+MODS=("tun" "rdma_rxe")
+
+exec > /dev/null
+
+# --- Helper: Cleanup Routine ---
+cleanup() {
+    echo "Cleaning up resources..."
+    rdma link del rxe0 2>/dev/null
+    ip link del tun0 2>/dev/null
+    for m in "${MODS[@]}"; do modprobe -r "$m" 2>/dev/null; done
+}
+
+# Ensure cleanup runs on script exit or interrupt
+trap cleanup EXIT
+
+# --- Phase 1: Environment Check ---
+if [[ $EUID -ne 0 ]]; then
+   echo "Error: This script must be run as root."
+   exit 1
+fi
+
+for m in "${MODS[@]}"; do
+    modprobe "$m" || { echo "Error: Failed to load $m"; exit 1; }
+done
+
+# --- Phase 2: Create Interfaces & RXE Links ---
+echo "Creating tun0 (1.1.1.1) and rxe0..."
+ip tuntap add mode tun tun0
+ip addr add 1.1.1.1/24 dev tun0
+ip link set tun0 up
+rdma link add rxe0 type rxe netdev tun0
+
+# Verify port 4791 is listening
+if ! ss -Huln sport = :$PORT | grep -q ":$PORT"; then
+    echo "Error: UDP port $PORT not found after rxe0 creation"
+    exit 1
+fi
+
+orig_s=`cat /sys/class/infiniband/rxe0/ports/1/counters/port_xmit_data`
+orig_r=`cat /sys/class/infiniband/rxe0/ports/1/counters/port_rcv_data`
+
+rping -s -a 1.1.1.1 -C 3 -v &
+sleep 1
+rping -c -a 1.1.1.1 -C 3 -d -v
+
+new_s=`cat /sys/class/infiniband/rxe0/ports/1/counters/port_xmit_data`
+new_r=`cat /sys/class/infiniband/rxe0/ports/1/counters/port_rcv_data`
+
+echo sent $new_s $orig_s
+echo rcvd $new_r $orig_r
+
+result0=$((new_s - orig_s))
+result1=$((new_r - orig_r))
+
+if [ $result0 != $result1 ]; then
+       echo "Error: sent and rcvd bytes different"
+       echo $result0
+       echo $result1
+       exit 1
+fi
+
+echo "Deleting rxe0..."
+rdma link del rxe0
+
+# Port should now be gone
+if ss -Huln sport = :$PORT | grep -q ":$PORT"; then
+    echo "Error: UDP port $PORT still exists after all links deleted"
+    exit 1
+fi
+
+echo "Test passed successfully."