xdpsock: Fix partial batch handling#567
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tohojo merged 2 commits intoxdp-project:mainfrom Apr 26, 2026
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OK, so I think you're correct that this is needed, but it's by no means obvious why. So please update the commit message with an explanation of why this change is needed (and by extension, what buggy behaviour it fixes).
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OK, sure. This issue was found while testing AF_XDP with the xdp-bench tool. I'll update the commit message to explain why this change is needed and what bug it fixes, and send a revised version soon. |
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Great, thank you! :)
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While running xdp-bench with AF_XDP sockets, the benchmark could run for a few seconds and then suddenly stop seeing packets. It turned out that xsk_ring_cons__peek() advances cached_cons immediately. If l2fwd(), rx_drop() or complete_tx_l2fwd() peeks a batch and then cannot reserve enough entries in the TX or FQ ring to process all of it, the remaining descriptors need to be cancelled explicitly. Otherwise the untouched descriptors can get stranded in the RX/CQ rings, so buffers are not recycled and the kernel eventually cannot deliver more packets or completions to the AF_XDP socket. Signed-off-by: Xiaoguang Wang <lege.wang@jaguarmicro.com>
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If l2fwd or rx_drop stops partway through a peeked batch, make sure the untouched descriptors are cancelled before we loop around again.