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loader: retry with xdp frags#41967

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julianwiedmann merged 1 commit intomainfrom
pr/vk/xdp/frags
Oct 7, 2025
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loader: retry with xdp frags#41967
julianwiedmann merged 1 commit intomainfrom
pr/vk/xdp/frags

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@viktor-kurchenko viktor-kurchenko commented Oct 1, 2025 •
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The commit adds retry logic in case the XDP program loading failed with the invalid argument error.
The error might indicate that the network interface is configured with a jumbo MTU, so we can retry loading after setting the BPF_F_XDP_HAS_FRAGS flag and hope that the NIC driver is XDP Fragment aware.

The log snippet during testing the retry on Mellanox NICs:

time=2025-10-01T[  895.435879] bond0: (slave enp2s0f0np0): Error -22 calling ndo_bpf
18:56:14.308738377Z level=info msg="No existing link found for program" module=agent.datapath.loader link=/sys/fs/bpf/cilium/devices/bond0/links/cil_xdp_entry progName=cil_xdp_entry
time=2025-10-01T18:56:14.316262698Z level=error msg="loading eBPF program failed, setting XDP frags and retrying" module=agent.datapath.loader error="interface bond0: attaching program cil_xdp_entry using bpf_link: failed to attach link: create link: invalid argument"
time=2025-10-01T18:56:14.323170977Z level=info msg="Fallback node addresses updated" module=agent.datapath.node-address addresses="147.28.240.155 (primary), 2604:1380:4091:3200::1 (primary)" device=*
time=2025-10-01T18:56:14.536337704Z level=info msg="No existing link found for program" module=agent.datapath.loader link=/sys/fs/bpf/cilium/devices/bond0/links/cil_xdp_entry progName=cil_xdp_entry
time=2025-10-01T18:56:15.108612512Z level=info msg="Program attached using bpf_link" module=agent.datapath.loader progName=cil_xdp_entry

Allow to attach Cilium's XDP program on network interfaces that have jumbo MTU configured and support xdp.frags program type.

@maintainer-s-little-helper maintainer-s-little-helper bot added the dont-merge/needs-release-note-label The author needs to describe the release impact of these changes. label Oct 1, 2025
@viktor-kurchenko viktor-kurchenko force-pushed the pr/vk/xdp/frags branch 3 times, most recently from ec4f818 to a74b4a4 Compare October 1, 2025 18:54
@viktor-kurchenko viktor-kurchenko changed the title XDP frags probe loader: retry with xdp frags Oct 1, 2025
@viktor-kurchenko viktor-kurchenko added area/loader Impacts the loading of BPF programs into the kernel. area/datapath Impacts bpf/ or low-level forwarding details, including map management and monitor messages. release-note/minor This PR changes functionality that users may find relevant to operating Cilium. labels Oct 1, 2025
@maintainer-s-little-helper maintainer-s-little-helper bot removed the dont-merge/needs-release-note-label The author needs to describe the release impact of these changes. label Oct 1, 2025
@viktor-kurchenko viktor-kurchenko marked this pull request as ready for review October 1, 2025 19:04
@viktor-kurchenko viktor-kurchenko requested a review from a team as a code owner October 1, 2025 19:04
dylandreimerink
dylandreimerink requested changes Oct 6, 2025
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Just one thing, looks good otherwise.

@viktor-kurchenko
loader: retry with xdp frags
610f6a1 
The commit adds retry logic in case the XDP program loading failed with
the `invalid argument` error. The error might indicate that the network
interface is configured with a jumbo MTU, so we can retry loading after
setting the `BPF_F_XDP_HAS_FRAGS` flag and hope that the NIC driver is XDP
Fragment aware.

Signed-off-by: viktor-kurchenko <viktor.kurchenko@isovalent.com>
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viktor-kurchenko commented Oct 6, 2025

/test

@maintainer-s-little-helper maintainer-s-little-helper bot added the ready-to-merge This PR has passed all tests and received consensus from code owners to merge. label Oct 6, 2025
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julianwiedmann commented Oct 7, 2025

👋 very nice! Could you also please give this PR a release-note stanza which describes the user-visible impact of the improvement?

@julianwiedmann julianwiedmann added this pull request to the merge queue Oct 7, 2025
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viktor-kurchenko commented Oct 7, 2025

👋 very nice! Could you also please give this PR a release-note stanza which describes the user-visible impact of the improvement?

Sure, but maybe you can point me to an example? I never did it before.

Merged via the queue into main with commit 62f4856 Oct 7, 2025
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@julianwiedmann julianwiedmann deleted the pr/vk/xdp/frags branch October 7, 2025 10:21
@cilium-release-bot cilium-release-bot bot moved this to Released in cilium v1.19.0 Feb 3, 2026
@ti-mo ti-mo added the needs-backport/1.18 This PR / issue needs backporting to the v1.18 branch label Feb 23, 2026
@ti-mo ti-mo mentioned this pull request Feb 23, 2026
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@ti-mo ti-mo added the backport-pending/1.18 The backport for Cilium 1.18.x for this PR is in progress. label Feb 23, 2026
@ti-mo ti-mo removed the needs-backport/1.18 This PR / issue needs backporting to the v1.18 branch label Feb 23, 2026
@github-actions github-actions bot added backport-done/1.18 The backport for Cilium 1.18.x for this PR is done. and removed backport-pending/1.18 The backport for Cilium 1.18.x for this PR is in progress. labels Feb 26, 2026
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area/datapath Impacts bpf/ or low-level forwarding details, including map management and monitor messages. area/loader Impacts the loading of BPF programs into the kernel. backport-done/1.18 The backport for Cilium 1.18.x for this PR is done. ready-to-merge This PR has passed all tests and received consensus from code owners to merge. release-note/minor This PR changes functionality that users may find relevant to operating Cilium.

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