net-af_xdp: Use correct number of channels from ethtool

Drivers use different fields to report the number of channels, so take
the maximum of all data channels (rx, tx, combined) when determining the
size of the xsk map. The current code used only 'combined' which was set
to 0 in some drivers e.g. mlx4.

Tested: compiled and run xdpsock -q 3 -r -S on mlx4

Signed-off-by: Luigi Rizzo <lrizzo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20191119001951.92930-1-lrizzo@google.com

diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index 303ed633417b9360a3d31ca0f67afd182ce09f54..8e0ffa800a71362fb6e93b4d9804cae20dfb79f7 100644 (file)
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -431,13 +431,18 @@ static int xsk_get_max_queues(struct xsk_socket *xsk)
                goto out;
        }
 
-       if (err || channels.max_combined == 0)
+       if (err) {
                /* If the device says it has no channels, then all traffic
                 * is sent to a single stream, so max queues = 1.
                 */
                ret = 1;
-       else
-               ret = channels.max_combined;
+       } else {
+               /* Take the max of rx, tx, combined. Drivers return
+                * the number of channels in different ways.
+                */
+               ret = max(channels.max_rx, channels.max_tx);
+               ret = max(ret, (int)channels.max_combined);
+       }
 
 out:
        close(fd);