[RFC bpf-next v3 10/14] selftests/xsk: Support XDP_TX_METADATA_LEN

[Stanislav Fomichev <sdf@xxxxxxxxxx>]

Add new config field and call setsockopt.

Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
---
 tools/testing/selftests/bpf/xsk.c | 17 +++++++++++++++++
 tools/testing/selftests/bpf/xsk.h |  1 +
 2 files changed, 18 insertions(+)

diff --git a/tools/testing/selftests/bpf/xsk.c b/tools/testing/selftests/bpf/xsk.c
index 687d83e707f8..c659713e2d43 100644
--- a/tools/testing/selftests/bpf/xsk.c
+++ b/tools/testing/selftests/bpf/xsk.c
@@ -47,6 +47,10 @@
  #define PF_XDP AF_XDP
 #endif
 
+#ifndef XDP_TX_METADATA_LEN
+#define XDP_TX_METADATA_LEN 9
+#endif
+
 #define pr_warn(fmt, ...) fprintf(stderr, fmt, ##__VA_ARGS__)
 
 #define XSKMAP_SIZE 1
@@ -124,12 +128,14 @@ static int xsk_set_xdp_socket_config(struct xsk_socket_config *cfg,
 		cfg->rx_size = XSK_RING_CONS__DEFAULT_NUM_DESCS;
 		cfg->tx_size = XSK_RING_PROD__DEFAULT_NUM_DESCS;
 		cfg->bind_flags = 0;
+		cfg->tx_metadata_len = 0;
 		return 0;
 	}
 
 	cfg->rx_size = usr_cfg->rx_size;
 	cfg->tx_size = usr_cfg->tx_size;
 	cfg->bind_flags = usr_cfg->bind_flags;
+	cfg->tx_metadata_len = usr_cfg->tx_metadata_len;
 
 	return 0;
 }
@@ -479,6 +485,17 @@ int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
 			umem->tx_ring_setup_done = true;
 	}
 
+	if (xsk->config.tx_metadata_len) {
+		int optval = xsk->config.tx_metadata_len;
+
+		err = setsockopt(xsk->fd, SOL_XDP, XDP_TX_METADATA_LEN,
+				 &optval, sizeof(optval));
+		if (err) {
+			err = -errno;
+			goto out_put_ctx;
+		}
+	}
+
 	err = xsk_get_mmap_offsets(xsk->fd, &off);
 	if (err) {
 		err = -errno;
diff --git a/tools/testing/selftests/bpf/xsk.h b/tools/testing/selftests/bpf/xsk.h
index 8da8d557768b..57e0af403aa8 100644
--- a/tools/testing/selftests/bpf/xsk.h
+++ b/tools/testing/selftests/bpf/xsk.h
@@ -212,6 +212,7 @@ struct xsk_socket_config {
 	__u32 rx_size;
 	__u32 tx_size;
 	__u16 bind_flags;
+	__u8 tx_metadata_len;
 };
 
 /* Set config to NULL to get the default configuration. */
-- 
2.41.0.255.g8b1d071c50-goog