The 01/22/2021 00:43, Rasmus Villemoes wrote:
>
> It's not true that switchdev_port_obj_notify() only inspects the
> ->handled field of "struct switchdev_notifier_port_obj_info" if
> call_switchdev_blocking_notifiers() returns 0 - there's a WARN_ON()
> triggering for a non-zero return combined with ->handled not being
> true. But the real problem here is that -EOPNOTSUPP is not being
> properly handled.
>
> The wrapper functions switchdev_handle_port_obj_add() et al change a
> return value of -EOPNOTSUPP to 0, and the treatment of ->handled in
> switchdev_port_obj_notify() seems to be designed to change that back
> to -EOPNOTSUPP in case nobody actually acted on the notifier (i.e.,
> everybody returned -EOPNOTSUPP).
>
> Currently, as soon as some device down the stack passes the check_cb()
> check, ->handled gets set to true, which means that
> switchdev_port_obj_notify() cannot actually ever return -EOPNOTSUPP.
>
> This, for example, means that the detection of hardware offload
> support in the MRP code is broken - br_mrp_set_ring_role() always ends
> up setting mrp->ring_role_offloaded to 1, despite not a single
> mainline driver implementing any of the SWITCHDEV_OBJ_ID*_MRP. So
> since the MRP code thinks the generation of MRP test frames has been
> offloaded, no such frames are actually put on the wire.
Just a small correction to what you have said regarding MRP. Is not the
option mrp->ring_role_offload that determines if the MRP Test frames are
generated by the HW but is the return value of the function
'br_mrp_switchdev_send_ring_test' called from function
'br_mrp_start_test'. But everything else looks good.
I have also started to work on a patch series where I try to improve the
way the return values of switchdev calls are handled in MRP. I should be
able to send these patches by the end of week.
>
> So, continue to set ->handled true if any callback returns success or
> any error distinct from -EOPNOTSUPP. But if all the callbacks return
> -EOPNOTSUPP, make sure that ->handled stays false, so the logic in
> switchdev_port_obj_notify() can propagate that information.
>
> Fixes: f30f0601eb93 ("switchdev: Add helpers to aid traversal through lower
> devices")
> Signed-off-by: Rasmus Villemoes <rasmus.villem...@prevas.dk>
> ---
> Resending with more folks on cc and a tentative fixes tag.
>
> net/switchdev/switchdev.c | 23 +++++++++++++----------
> 1 file changed, 13 insertions(+), 10 deletions(-)
>
> diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
> index 23d868545362..2c1ffc9ba2eb 100644
> --- a/net/switchdev/switchdev.c
> +++ b/net/switchdev/switchdev.c
> @@ -460,10 +460,11 @@ static int __switchdev_handle_port_obj_add(struct
> net_device *dev,
> extack = switchdev_notifier_info_to_extack(&port_obj_info->info);
>
> if (check_cb(dev)) {
> - /* This flag is only checked if the return value is success.
> */
> - port_obj_info->handled = true;
> - return add_cb(dev, port_obj_info->obj, port_obj_info->trans,
> - extack);
> + err = add_cb(dev, port_obj_info->obj, port_obj_info->trans,
> + extack);
> + if (err != -EOPNOTSUPP)
> + port_obj_info->handled = true;
> + return err;
> }
>
> /* Switch ports might be stacked under e.g. a LAG. Ignore the
> @@ -515,9 +516,10 @@ static int __switchdev_handle_port_obj_del(struct
> net_device *dev,
> int err = -EOPNOTSUPP;
>
> if (check_cb(dev)) {
> - /* This flag is only checked if the return value is success.
> */
> - port_obj_info->handled = true;
> - return del_cb(dev, port_obj_info->obj);
> + err = del_cb(dev, port_obj_info->obj);
> + if (err != -EOPNOTSUPP)
> + port_obj_info->handled = true;
> + return err;
> }
>
> /* Switch ports might be stacked under e.g. a LAG. Ignore the
> @@ -568,9 +570,10 @@ static int __switchdev_handle_port_attr_set(struct
> net_device *dev,
> int err = -EOPNOTSUPP;
>
> if (check_cb(dev)) {
> - port_attr_info->handled = true;
> - return set_cb(dev, port_attr_info->attr,
> - port_attr_info->trans);
> + err = set_cb(dev, port_attr_info->attr,
> port_attr_info->trans);
> + if (err != -EOPNOTSUPP)
> + port_attr_info->handled = true;
> + return err;
> }
>
> /* Switch ports might be stacked under e.g. a LAG. Ignore the
> --
> 2.23.0
>
--
/Horatiu
