xdp: add flags argument to ndo_xdp_xmit API

This patch only change the API and reject any use of flags. This is an
intermediate step that allows us to implement the flush flag operation
later, for each individual driver in a separate patch.

The plan is to implement flush operation via XDP_XMIT_FLUSH flag
and then remove XDP_XMIT_FLAGS_NONE when done.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
diff --git a/include/net/xdp.h b/include/net/xdp.h
index 7ad7792..0c45f0f 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -40,6 +40,11 @@ enum xdp_mem_type {
 	MEM_TYPE_MAX,
 };
 
+/* XDP flags for ndo_xdp_xmit */
+#define XDP_XMIT_FLAGS_NONE	0U
+#define XDP_XMIT_FLUSH		(1U << 0)	/* doorbell signal consumer */
+#define XDP_XMIT_FLAGS_MASK	XDP_XMIT_FLUSH
+
 struct xdp_mem_info {
 	u32 type; /* enum xdp_mem_type, but known size type */
 	u32 id;