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When HW GRO is enabled, forwarding of packets is broken due to gso_size being set incorrectly on non GRO packets. Non GRO packets have a skb GRO count of 1. mlx5 always sets gso_size on the skb, even for non GRO packets. It leans on the fact that gso_size is normally reset in napi_gro_complete(). But this happens only for packets from GRO'able protocols (TCP/UDP) that have a gro_receive() handler. The problematic scenarios are: 1) Non GRO protocol packets are received, validate_xmit_skb() will drop them (see EPROTONOSUPPORT in skb_mac_gso_segment()). The fix for this case would be to not set gso_size at all for SHAMPO packets with header size 0. 2) Packets from a GRO'ed protocol (TCP) are received but immediately flushed because they are not GRO'able (TCP SYN for example). mlx5e_shampo_update_hdr(), which updates the remaining GRO state on the skb, is not called because skb GRO count is 1. The fix here would be to always call mlx5e_shampo_update_hdr(), regardless of skb GRO count. But this call is expensive The unified fix for both cases is to reset gso_size before calling napi_gro_receive(). It is a change that is more effective (no call to mlx5e_shampo_update_hdr() necessary) and simple (smallest code footprint). Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com> Signed-off-by: Tariq Toukan <tariqt@nvidia.com> Link: https://lore.kernel.org/r/20240603212219.1037656-6-tariqt@nvidia.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.