BACKPORT: selftests: ncdevmem: Implement devmem TCP TX

Add support for devmem TX in ncdevmem.

This is a combination of the ncdevmem from the devmem TCP series RFCv1
which included the TX path, and work by Stan to include the netlink API
and refactored on top of his generic memory_provider support.

Signed-off-by: Mina Almasry <almasrymina@google.com>
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Pranjal Shrivastava <praan@google.com>

Author: pran005

tools/testing/selftests/drivers/net/hw/devmem.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 # SPDX-License-Identifier: GPL-2.0
 
+from os import path
 from lib.py import ksft_run, ksft_exit
 from lib.py import ksft_eq, KsftSkipEx
 from lib.py import NetDrvEpEnv
@@ -10,8 +11,7 @@
 
 def require_devmem(cfg):
     if not hasattr(cfg, "_devmem_probed"):
-        port = rand_port()
-        probe_command = f"./ncdevmem -f {cfg.ifname}"
+        probe_command = f"{cfg.bin_local} -f {cfg.ifname}"
         cfg._devmem_supported = cmd(probe_command, fail=False, shell=True).ret == 0
         cfg._devmem_probed = True
 
@@ -25,18 +25,34 @@ def check_rx(cfg) -> None:
     require_devmem(cfg)
 
     port = rand_port()
-    listen_cmd = f"./ncdevmem -l -f {cfg.ifname} -s {cfg.v6} -p {port}"
+    listen_cmd = f"{cfg.bin_local} -l -f {cfg.ifname} -s {cfg.addr_v['6']} -p {port}"
 
     with bkg(listen_cmd) as socat:
         wait_port_listen(port)
         cmd(f"echo -e \"hello\\nworld\"| socat -u - TCP6:[{cfg.v6}]:{port}", host=cfg.remote, shell=True)
 
     ksft_eq(socat.stdout.strip(), "hello\nworld")
 
+@ksft_disruptive
+def check_tx(cfg) -> None:
+    cfg.require_ipver("6")
+    require_devmem(cfg)
+
+    port = rand_port()
+    listen_cmd = f"socat -U - TCP6-LISTEN:{port}"
+
+    with bkg(listen_cmd, exit_wait=True) as socat:
+        wait_port_listen(port)
+        cmd(f"echo -e \"hello\\nworld\"| {cfg.bin_remote} -f {cfg.ifname} -s {cfg.addr_v['6']} -p {port}", host=cfg.remote, shell=True)
+
+    ksft_eq(socat.stdout.strip(), "hello\nworld")
 
 def main() -> None:
     with NetDrvEpEnv(__file__) as cfg:
-        ksft_run([check_rx],
+        cfg.bin_local = path.abspath(path.dirname(__file__) + "/ncdevmem")
+        cfg.bin_remote = cfg.remote.deploy(cfg.bin_local)
+
+        ksft_run([check_rx, check_tx],
                  args=(cfg, ))
     ksft_exit()