On Wed, Jan 21, 2026 at 5:12 PM Paolo Abeni [off-list ref] wrote:

Some/most devices implementing gso_partial need to disable the GSO partial
features when the IP ID can't be mangled; to that extend each of them
implements something alike the following[1]:

        if (skb->encapsulation && !(features & NETIF_F_TSO_MANGLEID))
                features &= ~NETIF_F_TSO;

in the ndo_features_check() op, which leads to a bit of duplicate code.

Later patch in the series will implement GSO partial support for virtual
devices, and the current status quo will require more duplicate code and
a new indirect call in the TX path for them.

Introduce the mangleid_features mask, allowing the core to disable NIC
features based on/requiring MANGLEID, without any further intervention
from the driver.

The same functionality could be alternatively implemented adding a single
boolean flag to the struct net_device, but would require an additional
checks in ndo_features_check().

Also note that [1] is incorrect if the NIC additionally implements
NETIF_F_GSO_UDP_L4, mangleid_features transparently handle even such a
case.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Reviewed-by: Eric Dumazet <edumazet@google.com>