xsk: add support for bind for Rx

Here, the bind syscall is added. Binding an AF_XDP socket, means
associating the socket to an umem, a netdev and a queue index. This
can be done in two ways.

The first way, creating a "socket from scratch". Create the umem using
the XDP_UMEM_REG setsockopt and an associated fill queue with
XDP_UMEM_FILL_QUEUE. Create the Rx queue using the XDP_RX_QUEUE
setsockopt. Call bind passing ifindex and queue index ("channel" in
ethtool speak).

The second way to bind a socket, is simply skipping the
umem/netdev/queue index, and passing another already setup AF_XDP
socket. The new socket will then have the same umem/netdev/queue index
as the parent so it will share the same umem. You must also set the
flags field in the socket address to XDP_SHARED_UMEM.

v2: Use PTR_ERR instead of passing error variable explicitly.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/net/xdp/xsk_queue.c b/net/xdp/xsk_queue.c
index 894f9f89afc7..d012e5e23591 100644
--- a/net/xdp/xsk_queue.c
+++ b/net/xdp/xsk_queue.c
@@ -16,6 +16,14 @@
 
 #include "xsk_queue.h"
 
+void xskq_set_umem(struct xsk_queue *q, struct xdp_umem_props *umem_props)
+{
+	if (!q)
+		return;
+
+	q->umem_props = *umem_props;
+}
+
 static u32 xskq_umem_get_ring_size(struct xsk_queue *q)
 {
 	return sizeof(struct xdp_umem_ring) + q->nentries * sizeof(u32);