net: Support partial checksum offloading

[WorldofJARcraft]

The Xilinx AXI Ethernet subsystem is capable of RX/Tx checksum offloading. While it supports computing IP and UDP/TCP checksums, it does not support computing ICMP checksums and only computes IP checksums for ICMP messages. Thus, this patch adds an default-disabled option for always computing the ICMP checksum in software while relying on hardware to compute the remaining checksums.

[pdgendt]

This should be a driver capability, not a global setting. If multiple drivers are used, each should work properly.

[rlubos]

Please check compliance results, there are missing spaces etc.

[rlubos]

Please check the compliance report.
Also the commit title could be updated, the changeset is no longer specific to ICMP.

[decsny]

This is convenient, I was planning to look into something like this after LTS because NXP ENET has the same limitation, it only doesn't accelerate ICMPv6 checksum

[WorldofJARcraft]

Please check the compliance report. Also the commit title could be updated, the changeset is no longer specific to ICMP.

Some of the complaints in the compliance report refer to code that I did not change. I could run the corresponding files through clang-format or manually fix the violations, but this would bloat the PR.
I have just pushed a new version that passes checkpatch locally:

git diff HEAD~1 HEAD | ./scripts/checkpatch.pl -

[rlubos]

nit: Please align with the opening bracket.

[WorldofJARcraft]

Done. Btw., the return type was also incorrect, this is fixed as well.

[rlubos]

Suggested change

	NET_IF_CHECKSUM_IPV4_UDP = NET_IF_CHECKSUM_IPV4_HEADER_BIT|
	NET_IF_CHECKSUM_UDP_BIT,
	NET_IF_CHECKSUM_IPV4_UDP = NET_IF_CHECKSUM_IPV4_HEADER_BIT |
	NET_IF_CHECKSUM_UDP_BIT,

etc, just reads better.

[WorldofJARcraft]

Done

[rlubos]

This is convenient, I was planning to look into something like this after LTS because NXP ENET has the same limitation, it only doesn't accelerate ICMPv6 checksum

@decsny Good to hear that - feel free to participate in the review, to make sure those changes fit your HW needs as well.

[WorldofJARcraft]

This is convenient, I was planning to look into something like this after LTS because NXP ENET has the same limitation, it only doesn't accelerate ICMPv6 checksum

@decsny Good to hear that - feel free to participate in the review, to make sure those changes fit your HW needs as well.

I have a draft implementation for the Xilinx AXI Ethernet subsystem, which is where I initially came across this issue, here: #73986

[decsny]

It feels kind of strange for this to come from the ethernet config, since this is not really a configuration but rather a hardware capability? why not come from the get_capabilities function?

[decsny]

blocking until question is answered

[WorldofJARcraft]

It feels kind of strange for this to come from the ethernet config, since this is not really a configuration but rather a hardware capability? why not come from the get_capabilities function?

The original motivation was to save bits in the existing hardware capabilities enum.
However, I think including checksum offloading in the configuration API actually makes more sense: For some devices, checksum offloading is a run-time configuration. For example, for the Xilinx AXI Ethernet, TX checksum offloading must be requested for each packet via the control stream / the "userapp" fields in the AXI DMA SG descriptor. If TX offloading is not requested, the NIC will gladly send a packet with no checksum. Integrating checksum offloading with the configuration interfaces makes it possible to enable and disable the feature and query whether it is currently active.

not going to block this but I will want to revisit this from the perspective of determining hardware supported features and not just software requests to enable/disable

[github-actions]

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