libxdp: Modify semantic of fill and comp in xsk_socket_opts

Use umem's fill_save and fill_comp if fill and comp in opts
are both unset when calling xsk_socket__create_opts(),
otherwise use what they are set in opts.
This is to keep the same semantic as xsk_socket__create() and
xsk_socket__create_shared().

Signed-off-by: Muyang Tian <[email protected]>

Author: tacslon

headers/xdp/xsk.h

@@ -259,10 +259,9 @@ struct xsk_socket_config {
  * 
  * @fill, @comp, @rx_size, @tx_size, @libxdp_flags, @xdp_flags,
  * @bind_flags
- *  If a socket with exclusive ownership of a umem is going to be
- *  created, keep @fill and @comp unset. If the umem is to be shared
- *  with other sockets, set @fill and @comp to the corresponding
- *  fields of the umem.
+ *  If @fill and @comp are both unset, fill_save and comp_save of
+ *  the umem will be assigned to them, otherwise keep what they
+ *  are set in opts.
  *  If the remaining fields are unset, they will be set to 
  *  default value (see `xsk_set_xdp_socket_config()`).
  * 

lib/libxdp/xsk.c

@@ -1072,13 +1072,17 @@ struct xsk_socket *xsk_socket__create_opts(const char *ifname,
 	}
 	rx = OPTS_GET(opts, rx, NULL);
 	tx = OPTS_GET(opts, tx, NULL);
-	fill = OPTS_GET(opts, fill, umem->fill_save);
-	comp = OPTS_GET(opts, comp, umem->comp_save);
+	fill = OPTS_GET(opts, fill, NULL);
+	comp = OPTS_GET(opts, comp, NULL);
 
 	if (!umem || !(rx || tx)) {
 		err = -EFAULT;
 		goto err;
 	}
+	if (!fill && !comp) {
+		fill = umem->fill_save;
+		comp = umem->comp_save;
+	}
 
 	xsk = calloc(1, sizeof(*xsk));
 	if (!xsk) {