Re: [PATCH RFC net-next v2 2/6] selftests: ncdevmem: Implement devmem TCP TX

Stanislav Fomichev
2025-01-31T17:45:46Z

On 01/30, Mina Almasry wrote:
> 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>
>
> ---
>
> 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/ncdevmem.c | 276 +++++++++++++++++-
> 1 file changed, 272 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/drivers/net/hw/ncdevmem.c b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
> index 19a6969643f4..8455f19ecd1a 100644
> --- a/tools/testing/selftests/drivers/net/hw/ncdevmem.c
> +++ b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
> @@ -40,15 +40,18 @@
> #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 <libmnl/libmnl.h>
> #include <linux/types.h>
> @@ -80,6 +83,8 @@ 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;
> @@ -93,6 +98,8 @@ 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);
> };
> @@ -153,6 +160,20 @@ 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)
> {
> @@ -170,6 +191,7 @@ 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,
> };
>
> @@ -188,7 +210,7 @@ void validate_buffer(void *line, size_t size)
> {
> static unsigned char seed = 1;
> unsigned char *ptr = line;
> - int errors = 0;
> + static int errors;
> size_t i;
>
> for (i = 0; i < size; i++) {
> @@ -202,7 +224,7 @@ void validate_buffer(void *line, size_t size)
> }
> seed++;
> if (seed == do_validation)
> - seed = 0;
> + seed = 1;
> }
>
> fprintf(stdout, "Validated buffer\n");
> @@ -394,6 +416,49 @@ 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;
> @@ -432,7 +497,7 @@ 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;
> @@ -686,6 +751,207 @@ 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;
> + int retries = 10;
> + __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, ret, "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(struct dmabuf_tx_cmsg))];
> + struct sockaddr_in6 server_sin;
> + struct sockaddr_in6 client_sin;
> + struct dmabuf_tx_cmsg ddmabuf;
> + struct ynl_sock *ys = NULL;
> + struct msghdr msg = {};
> + ssize_t line_size = 0;
> + struct cmsghdr *cmsg;
> + struct iovec iov[2];
> + uint64_t off = 100;
> + char *line = NULL;
> + size_t len = 0;
> + int socket_fd;
> + int ret, mid;
> + int opt = 1;
> +
> + 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, ret, "bindtodevice");
> +
> + if (bind_tx_queue(ifindex, mem->fd, &ys))
> + error(1, 0, "Failed to bind\n");
> +

[..]

> + 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, ret, "bind");
> +

Can we wrap the two above in 'if (client_ip) {}'? For my case, as long as
we do SO_BINDTODEVICE, the autobind will do the right thing and I don't
have to explicitly pass '-c' (ncdemem crashes right now if it's
not passed).

> + ret = setsockopt(socket_fd, SOL_SOCKET, SO_ZEROCOPY, &opt, sizeof(opt));
> + if (ret)
> + error(1, ret, "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, ret, "connect");

The most new error() invocations, you pass 'ret' as a second argument.
We need to use 'errno' instead where possible to give the users correct errors
for diagnostics.

> +
> + while (1) {
> + free(line);
> + line = NULL;
> + /* Subtract 1 from line_size to remove trailing newlines that
> + * get_line are surely to parse...
> + */
> + line_size = getline(&line, &len, stdin) - 1;
> +
> + if (line_size < 0)
> + break;
> +
> + mid = (line_size / 2) + 1;
> +
> + iov[0].iov_base = (void *)100;
> + iov[0].iov_len = mid;
> + iov[1].iov_base = (void *)2000;
> + iov[1].iov_len = line_size - mid;
> +
> + provider->memcpy_to_device(mem, (size_t)iov[0].iov_base, line,
> + iov[0].iov_len);

This generates the following on my side:

ncdevmem.c:911:15: warning: format specifies type 'int' but the argument has type 'uint64_t' (aka 'unsigned long') [-Wformat]
910 | "read line_size=%ld off=%d iov[0].iov_base=%d, iov[0].iov_len=%d, iov[1].iov_base=%d, iov[1].iov_len=%d\n",
| ~~
| %lu
911 | line_size, off, iov[0].iov_base, iov[0].iov_len,
| ^~~
ncdevmem.c:911:20: warning: format specifies type 'int' but the argument has type 'void *' [-Wformat]
910 | "read line_size=%ld off=%d iov[0].iov_base=%d, iov[0].iov_len=%d, iov[1].iov_base=%d, iov[1].iov_len=%d\n",
| ~~
911 | line_size, off, iov[0].iov_base, iov[0].iov_len,
| ^~~~~~~~~~~~~~~
ncdevmem.c:911:37: warning: format specifies type 'int' but the argument has type '__kernel_size_t' (aka 'unsigned long') [-Wformat]
910 | "read line_size=%ld off=%d iov[0].iov_base=%d, iov[0].iov_len=%d, iov[1].iov_base=%d, iov[1].iov_len=%d\n",
| ~~
| %lu
911 | line_size, off, iov[0].iov_base, iov[0].iov_len,
| ^~~~~~~~~~~~~~
ncdevmem.c:912:4: warning: format specifies type 'int' but the argument has type 'void *' [-Wformat]
910 | "read line_size=%ld off=%d iov[0].iov_base=%d, iov[0].iov_len=%d, iov[1].iov_base=%d, iov[1].iov_len=%d\n",
| ~~
911 | line_size, off, iov[0].iov_base, iov[0].iov_len,
912 | iov[1].iov_base, iov[1].iov_len);
| ^~~~~~~~~~~~~~~
ncdevmem.c:912:21: warning: format specifies type 'int' but the argument has type '__kernel_size_t' (aka 'unsigned long') [-Wformat]
910 | "read line_size=%ld off=%d iov[0].iov_base=%d, iov[0].iov_len=%d, iov[1].iov_base=%d, iov[1].iov_len=%d\n",
| ~~
| %lu
911 | line_size, off, iov[0].iov_base, iov[0].iov_len,
912 | iov[1].iov_base, iov[1].iov_len);
| ^~~~~~~~~~~~~~