Re: [PATCH bpf-next v5 3/8] net: ice: add xmo_rx_checksum callback

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The `ice_xdp_rx_checksum()` XDP metadata getter calls `ice_get_rx_csum()`, which has side effects that artificially inflate hardware error statistics and cause double-counting.
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--- Patch [3]: [PATCH bpf-next v5 3/8] net: ice: add xmo_rx_checksum callback ---
commit 741cd60a0647d5876e42a8815bc6526c4da474e1
Author: Lorenzo Bianconi <lorenzo@kernel.org>

net: ice: add xmo_rx_checksum callback

This patch implements the xmo_rx_checksum callback in the ice driver to report
RX checksum results to eBPF programs. It introduces the ice_get_rx_csum utility
routine to make the RX checksum code reusable from both ice_rx_csum() and
ice_xdp_rx_checksum().

> diff --git a/drivers/net/ethernet/intel/ice/ice_txrx_lib.c b/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> index e695a664e53d1..3aa82ff03d9e2 100644
> --- a/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> +++ b/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
[ ... ]
>  static void
> -ice_rx_csum(struct ice_rx_ring *ring, struct sk_buff *skb,
> -	    union ice_32b_rx_flex_desc *rx_desc, u16 ptype)
> +ice_get_rx_csum(const union ice_32b_rx_flex_desc *rx_desc, u16 ptype,
> +		struct ice_rx_ring *ring, enum xdp_checksum *ip_summed,
> +		u32 *cksum, u8 *cksum_level)
>  {
[ ... ]
>  	if (ipv4 && (rx_status0 & (BIT(ICE_RX_FLEX_DESC_STATUS0_XSUM_EIPE_S)))) {
>  		ring->vsi->back->hw_rx_eipe_error++;
> -		return;
> +		goto checksum_none;
>  	}
[ ... ]
>  checksum_fail:
>  	ring->vsi->back->hw_csum_rx_error++;
> +checksum_none:
> +	*ip_summed = XDP_CHECKSUM_NONE;
> +	*cksum_level = 0;
> +	*cksum = 0;
> +}
[ ... ]
> +static int ice_xdp_rx_checksum(const struct xdp_md *ctx,
> +			       enum xdp_checksum *ip_summed,
> +			       u32 *cksum, u8 *cksum_level)
> +{
> +	const struct libeth_xdp_buff *xdp_ext = (void *)ctx;
> +	const union ice_32b_rx_flex_desc *rx_desc = xdp_ext->desc;
> +	struct ice_rx_ring *ring;
> +
> +	ring = libeth_xdp_buff_to_rq(xdp_ext, typeof(*ring), xdp_rxq);
> +	ice_get_rx_csum(rx_desc, ice_get_ptype(rx_desc), ring, ip_summed,
> +			cksum, cksum_level);

[Severity: Medium]
Since ice_get_rx_csum() increments hw_rx_eipe_error and hw_csum_rx_error, does
calling it from the XDP metadata getter artificially inflate these statistics?

An eBPF program can call the metadata getter multiple times on a single packet,
which would cause multi-counting. Furthermore, if the program returns XDP_PASS,
the networking stack will process the packet and call ice_rx_csum() which
calls ice_get_rx_csum() again, resulting in double-counting for the error.

> +
> +	return 0;
> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260715-bpf-xdp-meta-rxcksum-v5-0-623d5c0d0ab7@kernel.org?part=3