xsk: Add getsockopt XDP_OPTIONS

Make it possible for the application to determine whether the AF_XDP
socket is running in zero-copy mode. To achieve this, add a new
getsockopt option XDP_OPTIONS that returns flags. The only flag
supported for now is the zero-copy mode indicator.

Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Acked-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 20 insertions, 0 deletions

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index b68a380f50b3..35ca531ac74e 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -650,6 +650,26 @@ static int xsk_getsockopt(struct socket *sock, int level, int optname,
 
                 return 0;
         }
+        case XDP_OPTIONS:
+        {
+                struct xdp_options opts = {};
+
+                if (len < sizeof(opts))
+                        return -EINVAL;
+
+                mutex_lock(&xs->mutex);
+                if (xs->zc)
+                        opts.flags |= XDP_OPTIONS_ZEROCOPY;
+                mutex_unlock(&xs->mutex);
+
+                len = sizeof(opts);
+                if (copy_to_user(optval, &opts, len))
+                        return -EFAULT;
+                if (put_user(len, optlen))
+                        return -EFAULT;
+
+                return 0;
+        }
         default:
                 break;
         }