I recently upgraded my kernel module implementing the Homa transport protocol from 4.15.18 to 5.4.80, and a GRO feature available in the older version seems to have gone away in the newer version. In particular, it used to be possible for a protocol's xxx_gro_receive function to force a packet up the stack immediately by returning that skb as the result of xxx_gro_receive. However, in the newer kernel version, these packets simply get queued on napi->rx_list; the queue doesn't get flushed up-stack until napi_complete_done is called or gro_normal_batch packets accumulate. For Homa, this extra level of queuing gets in the way.
Is there any way for a xxx_gro_receive function to force a packet (in particular, one of those in the list passed as first argument to xxx_gro_receive) up the protocol stack immediately? I suppose I could set gro_normal_batch to 1, but that might interfere with other protocols that really want the batching. -John-
