On 7/24/25 10:57, Paolo Abeni wrote:

On 7/23/25 2:32 AM, Chenyuan Yang wrote:

quoted

The xdp_convert_buff_to_frame() function can return NULL when there is
insufficient headroom in the buffer to store the xdp_frame structure
or when the driver didn't reserve enough tailroom for skb_shared_info.

AFAIC the sfc driver reserves both enough headroom and tailroom, but
this is after ebpf run, which in turn could consume enough headroom to
cause a failure, so I think this makes sense.

Your reasoning seems plausible to me.
However, I think the error path ought to more closely follow the existing
 error cases in logging a ratelimited message and calling the tracepoint.
I think the cleanest way to do this would be:
	if (unlikely(!xdpf))
		err = -ENOBUFS;
	else
		err = efx_xdp_tx_buffers(efx, 1, &xdpf, true);
 so that it can make use of the existing failure path.
Adding the check to efx_xdp_tx_buffers() is also an option.

-ed