From: Rasmus Villemoes rasmus.villemoes@prevas.dk
commit 20776b465c0c249f5e5b5b4fe077cd24ef1cda86 upstream.
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: switchdev_port_obj_add() used by br_mrp_switchdev_send_ring_test() always returns 0, so since the MRP code thinks the generation of MRP test frames has been offloaded, no such frames are actually put on the wire. Similarly, br_mrp_switchdev_set_ring_role() also always returns 0, causing mrp->ring_role_offloaded to be set to 1.
To fix this, 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: 9a9f26e8f7ea ("bridge: mrp: Connect MRP API with the switchdev API") Fixes: f30f0601eb93 ("switchdev: Add helpers to aid traversal through lower devices") Reviewed-by: Petr Machata petrm@nvidia.com Signed-off-by: Rasmus Villemoes rasmus.villemoes@prevas.dk Link: https://lore.kernel.org/r/20210125124116.102928-1-rasmus.villemoes@prevas.dk Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/switchdev/switchdev.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-)
--- a/net/switchdev/switchdev.c +++ b/net/switchdev/switchdev.c @@ -461,10 +461,11 @@ static int __switchdev_handle_port_obj_a 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 @@ -513,9 +514,10 @@ static int __switchdev_handle_port_obj_d 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 @@ -563,9 +565,10 @@ static int __switchdev_handle_port_attr_ 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