#!/bin/bash# SPDX-License-Identifier: GPL-2.0 # Setup script for running ksft tests over a real interface in loopback mode.# This scripts replaces the historical setup_loopback.sh. It puts# a (presumably) real hardware interface into loopback mode, creates macvlan# interfaces on top and places them in a network namespace for isolation.## NETIF env variable must be exported to indicate the real target device.# Note that the test will override NETIF with one of the macvlans, the# actual ksft test will only see the macvlans.## Example use:#   export NETIF=eth0#   ./net/lib/ksft_setup_loopback.sh ./drivers/net/gro.py if [ -z "$NETIF" ]; then    echo "Error: NETIF variable not set"    exit 1fiif ! [ -d "/sys/class/net/$NETIF" ]; then    echo "Error: Can't find $NETIF, invalid netdevice"    exit 1fi # Save original settings for cleanupreadonly FLUSH_PATH="/sys/class/net/${NETIF}/gro_flush_timeout"readonly IRQ_PATH="/sys/class/net/${NETIF}/napi_defer_hard_irqs"FLUSH_TIMEOUT="$(< "${FLUSH_PATH}")"readonly FLUSH_TIMEOUTHARD_IRQS="$(< "${IRQ_PATH}")"readonly HARD_IRQS SERVER_NS=$(mktemp -u server-XXXXXXXX)readonly SERVER_NSCLIENT_NS=$(mktemp -u client-XXXXXXXX)readonly CLIENT_NSreadonly SERVER_MAC="aa:00:00:00:00:02"readonly CLIENT_MAC="aa:00:00:00:00:01" # ksft expects addresses to communicate with remoteexport  LOCAL_V6=2001:db8:1::1export REMOTE_V6=2001:db8:1::2 cleanup() {    local exit_code=$?     echo "Cleaning up..."     # Remove macvlan interfaces and namespaces    ip -netns "${SERVER_NS}" link del dev server 2>/dev/null || true    ip netns del "${SERVER_NS}" 2>/dev/null || true    ip -netns "${CLIENT_NS}" link del dev client 2>/dev/null || true    ip netns del "${CLIENT_NS}" 2>/dev/null || true     # Disable loopback    ethtool -K "${NETIF}" loopback off 2>/dev/null || true    sleep 1     echo "${FLUSH_TIMEOUT}" >"${FLUSH_PATH}"    echo "${HARD_IRQS}" >"${IRQ_PATH}"     exit $exit_code} trap cleanup EXIT INT TERM # Enable loopback modeecho "Enabling loopback on ${NETIF}..."ethtool -K "${NETIF}" loopback on || {    echo "Failed to enable loopback mode"    exit 1}# The interface may need time to get carrier back, but selftests# will wait for carrier, so no need to wait / sleep here. # Use timer on  host to trigger the network stack# Also disable device interrupt to not depend on NIC interrupt# Reduce test flakiness caused by unexpected interruptsecho 100000 >"${FLUSH_PATH}"echo 50 >"${IRQ_PATH}" # Create server namespace with macvlanip netns add "${SERVER_NS}"ip link add link "${NETIF}" dev server address "${SERVER_MAC}" type macvlanip link set dev server netns "${SERVER_NS}"ip -netns "${SERVER_NS}" link set dev server upip -netns "${SERVER_NS}" addr add $LOCAL_V6/64 dev serverip -netns "${SERVER_NS}" link set dev lo up # Create client namespace with macvlanip netns add "${CLIENT_NS}"ip link add link "${NETIF}" dev client address "${CLIENT_MAC}" type macvlanip link set dev client netns "${CLIENT_NS}"ip -netns "${CLIENT_NS}" link set dev client upip -netns "${CLIENT_NS}" addr add $REMOTE_V6/64 dev clientip -netns "${CLIENT_NS}" link set dev lo up echo "Setup complete!"echo "  Device: ${NETIF}"echo "  Server NS: ${SERVER_NS}"echo "  Client NS: ${CLIENT_NS}"echo "" # Setup environment variables for testsexport NETIF=serverexport REMOTE_TYPE=netnsexport REMOTE_ARGS="${CLIENT_NS}" # Run the commandip netns exec "${SERVER_NS}" "$@"