[PATCH net-next 6/8] selftests: net: add flag to send a frame in xdp_helper

@@ -1,4 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
+#define _FILE_OFFSET_BITS 64
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>

@@ -19,15 +20,91 @@
 
 static void print_usage(const char *bin)
 {
-	fprintf(stderr, "Usage: %s ifindex queue_id [-z]\n\n"
-		"where:\n\t-z: force zerocopy mode", bin);
+	fprintf(stderr, "Usage: %s ifindex queue_id [-z] [-t frame_hex]\n\n"
+		"where:\n\t-z: force zerocopy mode\n"
+		"\t-t: send one frame, given in hex, and exit\n", bin);
+}
+
+static int parse_frame(unsigned char *buf, const char *hex)
+{
+	size_t len = strlen(hex) / 2;
+	size_t i;
+
+	if (!len || len > 2048 || strlen(hex) % 2 ||
+	    strspn(hex, "0123456789abcdefABCDEF") != strlen(hex))
+		return -1;
+	for (i = 0; i < len; i++)
+		if (sscanf(hex + 2 * i, "%2hhx", &buf[i]) != 1)
+			return -1;
+	return len;
+}
+
+/* Send the frame at UMEM address 0 and wait until its descriptor shows up
+ * on the completion ring. In copy mode this happens when the skb is freed.
+ */
+static int send_frame(int sock_fd, __u32 len)
+{
+	struct xdp_mmap_offsets off;
+	socklen_t optlen = sizeof(off);
+	struct xdp_desc *desc;
+	size_t tx_sz, cq_sz;
+	char *tx, *cq;
+	int ret = 1;
+	int i;
+
+	if (getsockopt(sock_fd, SOL_XDP, XDP_MMAP_OFFSETS, &off, &optlen)) {
+		perror("getsockopt failed");
+		return 1;
+	}
+
+	tx_sz = off.tx.desc + NUM_DESC * sizeof(*desc);
+	tx = mmap(NULL, tx_sz, PROT_READ | PROT_WRITE, MAP_SHARED, sock_fd,
+		  XDP_PGOFF_TX_RING);
+	if (tx == MAP_FAILED) {
+		perror("TX ring mmap failed");
+		return 1;
+	}
+
+	cq_sz = off.cr.desc + NUM_DESC * sizeof(__u64);
+	cq = mmap(NULL, cq_sz, PROT_READ | PROT_WRITE, MAP_SHARED, sock_fd,
+		  XDP_UMEM_PGOFF_COMPLETION_RING);
+	if (cq == MAP_FAILED) {
+		perror("completion ring mmap failed");
+		goto out_tx;
+	}
+
+	desc = (struct xdp_desc *)(tx + off.tx.desc);
+	desc->addr = 0;
+	desc->len = len;
+	__atomic_store_n((__u32 *)(tx + off.tx.producer), 1, __ATOMIC_RELEASE);
+
+	if (sendto(sock_fd, NULL, 0, MSG_DONTWAIT, NULL, 0) < 0) {
+		perror("sendto failed");
+		goto out;
+	}
+
+	for (i = 0; i < 100; i++) {
+		usleep(10000);
+		if (__atomic_load_n((__u32 *)(cq + off.cr.producer),
+				    __ATOMIC_ACQUIRE)) {
+			ret = 0;
+			goto out;
+		}
+	}
+
+	fprintf(stderr, "no TX completion\n");
+out:
+	munmap(cq, cq_sz);
+out_tx:
+	munmap(tx, tx_sz);
+	return ret;
 }
 
 /* this is a simple helper program that creates an XDP socket and does the
  * minimum necessary to get bind() to succeed.
  *
- * this test program is not intended to actually process packets, but could be
- * extended in the future if that is actually needed.
+ * without -t it does not process packets. with -t it sends one frame
+ * through the TX ring and exits once the frame completes.
  *
  * it is used by queues.py to ensure the xsk netlinux attribute is set
  * correctly.

@@ -37,13 +114,16 @@ int main(int argc, char **argv)
 	struct xdp_umem_reg umem_reg = { 0 };
 	struct sockaddr_xdp sxdp = { 0 };
 	int num_desc = NUM_DESC;
+	int frame_len = 0;
 	void *umem_area;
 	int retry = 0;
 	int ifindex;
 	int sock_fd;
 	int queue;
+	int ret;
+	int i;
 
-	if (argc != 3 && argc != 4) {
+	if (argc < 3) {
 		print_usage(argv[0]);
 		return 1;
 	}

@@ -94,9 +174,21 @@ int main(int argc, char **argv)
 	sxdp.sxdp_queue_id = queue;
 	sxdp.sxdp_flags = 0;
 
-	if (argc > 3) {
-		if (!strcmp(argv[3], "-z")) {
+	for (i = 3; i < argc; i++) {
+		if (!strcmp(argv[i], "-z")) {
 			sxdp.sxdp_flags = XDP_ZEROCOPY;
+		} else if (!strcmp(argv[i], "-t") && i + 1 < argc &&
+			   !frame_len) {
+			frame_len = parse_frame(umem_area, argv[++i]);
+			if (frame_len < 0) {
+				print_usage(argv[0]);
+				return 1;
+			}
+			if (setsockopt(sock_fd, SOL_XDP, XDP_TX_RING, &num_desc,
+				       sizeof(num_desc))) {
+				perror("setsockopt XDP_TX_RING failed");
+				return 1;
+			}
 		} else {
 			print_usage(argv[0]);
 			return 1;

@@ -119,6 +211,13 @@ int main(int argc, char **argv)
 		}
 	}
 
+	if (frame_len) {
+		ret = send_frame(sock_fd, frame_len);
+		munmap(umem_area, UMEM_SZ);
+		close(sock_fd);
+		return ret;
+	}
+
 	ksft_ready();
 	ksft_wait();