Re: [PATCH net-next 3/6] net: bcmgenet: add basic XDP support (PASS/DROP)

[Nicolai Buchwitz <nb@tipi-net.de>]

On 13.3.2026 23:48, Florian Fainelli wrote:
> On 3/13/26 02:20, Nicolai Buchwitz wrote:
>> Add XDP program attachment via ndo_bpf and execute XDP programs in the
>> RX path. Supported actions:
>> 
>>    - XDP_PASS: build SKB from the (possibly modified) xdp_buff and 
>> pass
>>      to the network stack, handling xdp_adjust_head/tail correctly
>>    - XDP_DROP: return the page to page_pool, no SKB allocated
>>    - XDP_ABORTED: same as DROP with trace_xdp_exception
>> 
>> XDP_TX and XDP_REDIRECT are not yet supported and will return
>> XDP_ABORTED.
>> 
>> The XDP hook runs after the HW error checks but before SKB 
>> construction,
>> so dropped packets avoid all SKB allocation overhead.
>> 
>> Advertise NETDEV_XDP_ACT_BASIC in xdp_features.
>> 
>> Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>
>> ---
> 
> [snip]
> 
>> @@ -2345,12 +2397,6 @@ static unsigned int bcmgenet_desc_rx(struct 
>> bcmgenet_rx_ring *ring,
>>   		hard_start = page_address(rx_page) + rx_off;
>>   		status = (struct status_64 *)hard_start;
>>   		dma_length_status = status->length_status;
>> -		if (dev->features & NETIF_F_RXCSUM) {
>> -			rx_csum = (__force __be16)(status->rx_csum & 0xffff);
>> -			if (rx_csum) {
>> -				/* defer csum setup to after skb is built */
>> -			}
>> -		}
> 
> Did you intend for that hunk to be deleted?

Yes, (kinda) intentional. Patch 1 moved the csum setup after SKB 
construction
(since we no longer have an SKB at that point), but left the early read
as a dead no-op - patch 3 then removed it. I'll clean this up in v2 by
dropping the dead block directly in patch 1 instead.

Nicolai