[PATCH net-next v7 9/9] selftests: ncdevmem: Implement devmem TCP TX

Mina Almasry
2025-03-08T21:41:02Z

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>

---

v5:
- Remove unnecassyr socat bindings (Stan).
- Add exit_wait=True (Stan)
- Remove unnecessary -c arg to ncdevmem in check_tx.

v4:
- Add TX test to devmem.py (Paolo).

v3:
- Update ncdevmem docs to run validation with RX-only and RX-with-TX.
- Fix build warnings (Stan).
- Make the validation expect new lines in the pattern so we can have the
TX path behave like netcat (Stan).
- Change ret to errno in error() calls (Stan).
- Handle the case where client_ip is not provided (Stan).
- Don't assume mid is <= 2000 (Stan).

v2:
- make errors a static variable so that we catch instances where there
are less than 20 errors across different buffers.
- Fix the issue where the seed is reset to 0 instead of its starting
value 1.
- Use 1000ULL instead of 1000 to guard against overflow (Willem).
- Do not set POLLERR (Willem).
- Update the test to use the new interface where iov_base is the
dmabuf_offset.
- Update the test to send 2 iov instead of 1, so we get some test
coverage over sending multiple iovs at once.
- Print the ifindex the test is using, useful for debugging issues where
maybe the test may fail because the ifindex of the socket is different
from the dmabuf binding.

---
.../selftests/drivers/net/hw/devmem.py | 26 +-
.../selftests/drivers/net/hw/ncdevmem.c | 300 +++++++++++++++++-
2 files changed, 311 insertions(+), 15 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/hw/devmem.py b/tools/testing/selftests/drivers/net/hw/devmem.py
index 3947e9157115..7fc686cf47a2 100755
--- a/tools/testing/selftests/drivers/net/hw/devmem.py
+++ b/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 @@ from lib.py import ksft_disruptive

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

@@ -25,7 +25,7 @@ def check_rx(cfg) -> None:
require_devmem(cfg)

port = rand_port()
- listen_cmd = f"./ncdevmem -l -f {cfg.ifname} -s {cfg.addr_v['6']} -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)
@@ -34,9 +34,27 @@ def check_rx(cfg) -> None:
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()

diff --git a/tools/testing/selftests/drivers/net/hw/ncdevmem.c b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
index 2bf14ac2b8c6..f801a1b3545f 100644
--- a/tools/testing/selftests/drivers/net/hw/ncdevmem.c
+++ b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
@@ -9,22 +9,31 @@
* ncdevmem -s <server IP> [-c <client IP>] -f eth1 -l -p 5201
*
* On client:
- * echo -n "hello\nworld" | nc -s <server IP> 5201 -p 5201
+ * echo -n "hello\nworld" | \
+ * ncdevmem -s <server IP> [-c <client IP>] -p 5201 -f eth1
*
- * Test data validation:
+ * Note this is compatible with regular netcat. i.e. the sender or receiver can
+ * be replaced with regular netcat to test the RX or TX path in isolation.
+ *
+ * Test data validation (devmem TCP on RX only):
*
* On server:
* ncdevmem -s <server IP> [-c <client IP>] -f eth1 -l -p 5201 -v 7
*
* On client:
* yes $(echo -e \\x01\\x02\\x03\\x04\\x05\\x06) | \
- * tr \\n \\0 | \
- * head -c 5G | \
+ * head -c 1G | \
* nc <server IP> 5201 -p 5201
*
+ * Test data validation (devmem TCP on RX and TX, validation happens on RX):
*
- * Note this is compatible with regular netcat. i.e. the sender or receiver can
- * be replaced with regular netcat to test the RX or TX path in isolation.
+ * On server:
+ * ncdevmem -s <server IP> [-c <client IP>] -l -p 5201 -v 8 -f eth1
+ *
+ * On client:
+ * yes $(echo -e \\x01\\x02\\x03\\x04\\x05\\x06\\x07) | \
+ * head -c 1M | \
+ * ncdevmem -s <server IP> [-c <client IP>] -p 5201 -f eth1
*/
#define _GNU_SOURCE
#define __EXPORTED_HEADERS__
@@ -40,15 +49,18 @@
#include <fcntl.h>
#include <malloc.h>
#include <error.h>
+#include <poll.h>

#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <sys/syscall.h>
+#include <sys/time.h>

#include <linux/memfd.h>
#include <linux/dma-buf.h>
+#include <linux/errqueue.h>
#include <linux/udmabuf.h>
#include <linux/types.h>
#include <linux/netlink.h>
@@ -79,6 +91,8 @@ static int num_queues = -1;
static char *ifname;
static unsigned int ifindex;
static unsigned int dmabuf_id;
+static uint32_t tx_dmabuf_id;
+static int waittime_ms = 500;

struct memory_buffer {
int fd;
@@ -92,6 +106,8 @@ struct memory_buffer {
struct memory_provider {
struct memory_buffer *(*alloc)(size_t size);
void (*free)(struct memory_buffer *ctx);
+ void (*memcpy_to_device)(struct memory_buffer *dst, size_t off,
+ void *src, int n);
void (*memcpy_from_device)(void *dst, struct memory_buffer *src,
size_t off, int n);
};
@@ -152,6 +168,20 @@ static void udmabuf_free(struct memory_buffer *ctx)
free(ctx);
}

+static void udmabuf_memcpy_to_device(struct memory_buffer *dst, size_t off,
+ void *src, int n)
+{
+ struct dma_buf_sync sync = {};
+
+ sync.flags = DMA_BUF_SYNC_START | DMA_BUF_SYNC_WRITE;
+ ioctl(dst->fd, DMA_BUF_IOCTL_SYNC, &sync);
+
+ memcpy(dst->buf_mem + off, src, n);
+
+ sync.flags = DMA_BUF_SYNC_END | DMA_BUF_SYNC_WRITE;
+ ioctl(dst->fd, DMA_BUF_IOCTL_SYNC, &sync);
+}
+
static void udmabuf_memcpy_from_device(void *dst, struct memory_buffer *src,
size_t off, int n)
{
@@ -169,6 +199,7 @@ static void udmabuf_memcpy_from_device(void *dst, struct memory_buffer *src,
static struct memory_provider udmabuf_memory_provider = {
.alloc = udmabuf_alloc,
.free = udmabuf_free,
+ .memcpy_to_device = udmabuf_memcpy_to_device,
.memcpy_from_device = udmabuf_memcpy_from_device,
};

@@ -187,14 +218,16 @@ void validate_buffer(void *line, size_t size)
{
static unsigned char seed = 1;
unsigned char *ptr = line;
- int errors = 0;
+ unsigned char expected;
+ static int errors;
size_t i;

for (i = 0; i < size; i++) {
- if (ptr[i] != seed) {
+ expected = seed ? seed : '\n';
+ if (ptr[i] != expected) {
fprintf(stderr,
"Failed validation: expected=%u, actual=%u, index=%lu\n",
- seed, ptr[i], i);
+ expected, ptr[i], i);
errors++;
if (errors > 20)
error(1, 0, "validation failed.");
@@ -393,6 +426,49 @@ static int bind_rx_queue(unsigned int ifindex, unsigned int dmabuf_fd,
return -1;
}

+static int bind_tx_queue(unsigned int ifindex, unsigned int dmabuf_fd,
+ struct ynl_sock **ys)
+{
+ struct netdev_bind_tx_req *req = NULL;
+ struct netdev_bind_tx_rsp *rsp = NULL;
+ struct ynl_error yerr;
+
+ *ys = ynl_sock_create(&ynl_netdev_family, &yerr);
+ if (!*ys) {
+ fprintf(stderr, "YNL: %s\n", yerr.msg);
+ return -1;
+ }
+
+ req = netdev_bind_tx_req_alloc();
+ netdev_bind_tx_req_set_ifindex(req, ifindex);
+ netdev_bind_tx_req_set_fd(req, dmabuf_fd);
+
+ rsp = netdev_bind_tx(*ys, req);
+ if (!rsp) {
+ perror("netdev_bind_tx");
+ goto err_close;
+ }
+
+ if (!rsp->_present.id) {
+ perror("id not present");
+ goto err_close;
+ }
+
+ fprintf(stderr, "got tx dmabuf id=%d\n", rsp->id);
+ tx_dmabuf_id = rsp->id;
+
+ netdev_bind_tx_req_free(req);
+ netdev_bind_tx_rsp_free(rsp);
+
+ return 0;
+
+err_close:
+ fprintf(stderr, "YNL failed: %s\n", (*ys)->err.msg);
+ netdev_bind_tx_req_free(req);
+ ynl_sock_destroy(*ys);
+ return -1;
+}
+
static void enable_reuseaddr(int fd)
{
int opt = 1;
@@ -431,7 +507,7 @@ static int parse_address(const char *str, int port, struct sockaddr_in6 *sin6)
return 0;
}

-int do_server(struct memory_buffer *mem)
+static int do_server(struct memory_buffer *mem)
{
char ctrl_data[sizeof(int) * 20000];
struct netdev_queue_id *queues;
@@ -685,6 +761,206 @@ void run_devmem_tests(void)
provider->free(mem);
}

+static uint64_t gettimeofday_ms(void)
+{
+ struct timeval tv;
+
+ gettimeofday(&tv, NULL);
+ return (tv.tv_sec * 1000ULL) + (tv.tv_usec / 1000ULL);
+}
+
+static int do_poll(int fd)
+{
+ struct pollfd pfd;
+ int ret;
+
+ pfd.revents = 0;
+ pfd.fd = fd;
+
+ ret = poll(&pfd, 1, waittime_ms);
+ if (ret == -1)
+ error(1, errno, "poll");
+
+ return ret && (pfd.revents & POLLERR);
+}
+
+static void wait_compl(int fd)
+{
+ int64_t tstop = gettimeofday_ms() + waittime_ms;
+ char control[CMSG_SPACE(100)] = {};
+ struct sock_extended_err *serr;
+ struct msghdr msg = {};
+ struct cmsghdr *cm;
+ __u32 hi, lo;
+ int ret;
+
+ msg.msg_control = control;
+ msg.msg_controllen = sizeof(control);
+
+ while (gettimeofday_ms() < tstop) {
+ if (!do_poll(fd))
+ continue;
+
+ ret = recvmsg(fd, &msg, MSG_ERRQUEUE);
+ if (ret < 0) {
+ if (errno == EAGAIN)
+ continue;
+ error(1, errno, "recvmsg(MSG_ERRQUEUE)");
+ return;
+ }
+ if (msg.msg_flags & MSG_CTRUNC)
+ error(1, 0, "MSG_CTRUNC\n");
+
+ for (cm = CMSG_FIRSTHDR(&msg); cm; cm = CMSG_NXTHDR(&msg, cm)) {
+ if (cm->cmsg_level != SOL_IP &&
+ cm->cmsg_level != SOL_IPV6)
+ continue;
+ if (cm->cmsg_level == SOL_IP &&
+ cm->cmsg_type != IP_RECVERR)
+ continue;
+ if (cm->cmsg_level == SOL_IPV6 &&
+ cm->cmsg_type != IPV6_RECVERR)
+ continue;
+
+ serr = (void *)CMSG_DATA(cm);
+ if (serr->ee_origin != SO_EE_ORIGIN_ZEROCOPY)
+ error(1, 0, "wrong origin %u", serr->ee_origin);
+ if (serr->ee_errno != 0)
+ error(1, 0, "wrong errno %d", serr->ee_errno);
+
+ hi = serr->ee_data;
+ lo = serr->ee_info;
+
+ fprintf(stderr, "tx complete [%d,%d]\n", lo, hi);
+ return;
+ }
+ }
+
+ error(1, 0, "did not receive tx completion");
+}
+
+static int do_client(struct memory_buffer *mem)
+{
+ char ctrl_data[CMSG_SPACE(sizeof(__u32))];
+ struct sockaddr_in6 server_sin;
+ struct sockaddr_in6 client_sin;
+ struct ynl_sock *ys = NULL;
+ struct msghdr msg = {};
+ ssize_t line_size = 0;
+ struct cmsghdr *cmsg;
+ struct iovec iov[2];
+ char *line = NULL;
+ unsigned long mid;
+ size_t len = 0;
+ int socket_fd;
+ __u32 ddmabuf;
+ int opt = 1;
+ int ret;
+
+ ret = parse_address(server_ip, atoi(port), &server_sin);
+ if (ret < 0)
+ error(1, 0, "parse server address");
+
+ socket_fd = socket(AF_INET6, SOCK_STREAM, 0);
+ if (socket_fd < 0)
+ error(1, socket_fd, "create socket");
+
+ enable_reuseaddr(socket_fd);
+
+ ret = setsockopt(socket_fd, SOL_SOCKET, SO_BINDTODEVICE, ifname,
+ strlen(ifname) + 1);
+ if (ret)
+ error(1, errno, "bindtodevice");
+
+ if (bind_tx_queue(ifindex, mem->fd, &ys))
+ error(1, 0, "Failed to bind\n");
+
+ if (client_ip) {
+ ret = parse_address(client_ip, atoi(port), &client_sin);
+ if (ret < 0)
+ error(1, 0, "parse client address");
+
+ ret = bind(socket_fd, &client_sin, sizeof(client_sin));
+ if (ret)
+ error(1, errno, "bind");
+ }
+
+ ret = setsockopt(socket_fd, SOL_SOCKET, SO_ZEROCOPY, &opt, sizeof(opt));
+ if (ret)
+ error(1, errno, "set sock opt");
+
+ fprintf(stderr, "Connect to %s %d (via %s)\n", server_ip,
+ ntohs(server_sin.sin6_port), ifname);
+
+ ret = connect(socket_fd, &server_sin, sizeof(server_sin));
+ if (ret)
+ error(1, errno, "connect");
+
+ while (1) {
+ free(line);
+ line = NULL;
+ line_size = getline(&line, &len, stdin);
+
+ if (line_size < 0)
+ break;
+
+ mid = (line_size / 2) + 1;
+
+ iov[0].iov_base = (void *)1;
+ iov[0].iov_len = mid;
+ iov[1].iov_base = (void *)(mid + 2);
+ iov[1].iov_len = line_size - mid;
+
+ provider->memcpy_to_device(mem, (size_t)iov[0].iov_base, line,
+ iov[0].iov_len);
+ provider->memcpy_to_device(mem, (size_t)iov[1].iov_base,
+ line + iov[0].iov_len,
+ iov[1].iov_len);
+
+ fprintf(stderr,
+ "read line_size=%ld iov[0].iov_base=%lu, iov[0].iov_len=%lu, iov[1].iov_base=%lu, iov[1].iov_len=%lu\n",
+ line_size, (unsigned long)iov[0].iov_base,
+ iov[0].iov_len, (unsigned long)iov[1].iov_base,
+ iov[1].iov_len);
+
+ msg.msg_iov = iov;
+ msg.msg_iovlen = 2;
+
+ msg.msg_control = ctrl_data;
+ msg.msg_controllen = sizeof(ctrl_data);
+
+ cmsg = CMSG_FIRSTHDR(&msg);
+ cmsg->cmsg_level = SOL_SOCKET;
+ cmsg->cmsg_type = SCM_DEVMEM_DMABUF;
+ cmsg->cmsg_len = CMSG_LEN(sizeof(__u32));
+
+ ddmabuf = tx_dmabuf_id;
+
+ *((__u32 *)CMSG_DATA(cmsg)) = ddmabuf;
+
+ ret = sendmsg(socket_fd, &msg, MSG_ZEROCOPY);
+ if (ret < 0)
+ error(1, errno, "Failed sendmsg");
+
+ fprintf(stderr, "sendmsg_ret=%d\n", ret);
+
+ if (ret != line_size)
+ error(1, errno, "Did not send all bytes");
+
+ wait_compl(socket_fd);
+ }
+
+ fprintf(stderr, "%s: tx ok\n", TEST_PREFIX);
+
+ free(line);
+ close(socket_fd);
+
+ if (ys)
+ ynl_sock_destroy(ys);
+
+ return 0;
+}
+
int main(int argc, char *argv[])
{
struct memory_buffer *mem;
@@ -728,6 +1004,8 @@ int main(int argc, char *argv[])

ifindex = if_nametoindex(ifname);

+ fprintf(stderr, "using ifindex=%u\n", ifindex);
+
if (!server_ip && !client_ip) {
if (start_queue < 0 && num_queues < 0) {
num_queues = rxq_num(ifindex);
@@ -778,7 +1056,7 @@ int main(int argc, char *argv[])
error(1, 0, "Missing -p argument\n");

mem = provider->alloc(getpagesize() * NUM_PAGES);
- ret = is_server ? do_server(mem) : 1;
+ ret = is_server ? do_server(mem) : do_client(mem);
provider->free(mem);

return ret;
--
2.49.0.rc0.332.g42c0ae87b1-goog