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, 5 insertions, 0 deletions

diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index e1f627d0cc1c..9bac1ad570fa 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -248,3 +248,8 @@ out:
 	put_pid(umem->pid);
 	return err;
 }
+
+bool xdp_umem_validate_queues(struct xdp_umem *umem)
+{
+	return umem->fq;
+}