Re: [PATCH v3 bpf-next 3/8] veth: Avoid drops by oversized packets when XDP is enabled
From: Toshiaki Makita <hidden>
Date: 2018-07-24 10:45:46
On 2018/07/24 10:56, Toshiaki Makita wrote:
On 2018/07/24 9:27, Jakub Kicinski wrote:quoted
On Mon, 23 Jul 2018 00:13:03 +0900, Toshiaki Makita wrote:quoted
From: Toshiaki Makita <redacted> All oversized packets including GSO packets are dropped if XDP is enabled on receiver side, so don't send such packets from peer. Drop TSO and SCTP fragmentation features so that veth devices themselves segment packets with XDP enabled. Also cap MTU accordingly. Signed-off-by: Toshiaki Makita <redacted>Is there any precedence for fixing up features and MTU like this? Most drivers just refuse to install the program if settings are incompatible.I don't know any precedence. I can refuse the program on installing it when features and MTU are not appropriate. Is it preferred? Note that with current implementation wanted_features are not touched so features will be restored when the XDP program is removed. MTU will not be restored though, as I do not remember the original MTU.
I just recalled that virtio_net used to refused XDP when guest offload features are incompatible but now it dynamically fixup them on installing an XDP program. https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3f93522ffab2d46a36b57adf324a54e674fc9536 -- Toshiaki Makita