xsk: Add shared umem support between devices

Add support to share a umem between different devices. This mode
can be invoked with the XDP_SHARED_UMEM bind flag. Previously,
sharing was only supported within the same device. Note that when
sharing a umem between devices, just as in the case of sharing a
umem between queue ids, you need to create a fill ring and a
completion ring and tie them to the socket (with two setsockopts,
one for each ring) before you do the bind with the
XDP_SHARED_UMEM flag. This so that the single-producer
single-consumer semantics of the rings can be upheld.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Link: https://lore.kernel.org/bpf/1598603189-32145-13-git-send-email-magnus.karlsson@intel.com

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index ea8d2ec..5eb6662 100644 (file)
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -701,14 +701,11 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
                        sockfd_put(sock);
                        goto out_unlock;
                }
-               if (umem_xs->dev != dev) {
-                       err = -EINVAL;
-                       sockfd_put(sock);
-                       goto out_unlock;
-               }
 
-               if (umem_xs->queue_id != qid) {
-                       /* Share the umem with another socket on another qid */
+               if (umem_xs->queue_id != qid || umem_xs->dev != dev) {
+                       /* Share the umem with another socket on another qid
+                        * and/or device.
+                        */
                        xs->pool = xp_create_and_assign_umem(xs,
                                                             umem_xs->umem);
                        if (!xs->pool) {