[dpdk-dev] [PATCH v6 2/6] gso: add TCP/IPv4 GSO support

Ananyev, Konstantin konstantin.ananyev at intel.com
Wed Oct 4 16:49:06 CEST 2017


> >>  int
> >>  rte_gso_segment(struct rte_mbuf *pkt,
> >> @@ -41,12 +46,53 @@
> >>  		struct rte_mbuf **pkts_out,
> >>  		uint16_t nb_pkts_out)
> >>  {
> >> +	struct rte_mempool *direct_pool, *indirect_pool;
> >> +	struct rte_mbuf *pkt_seg;
> >> +	uint64_t ol_flags;
> >> +	uint16_t gso_size;
> >> +	uint8_t ipid_delta;
> >> +	int ret = 1;
> >> +
> >>  	if (pkt == NULL || pkts_out == NULL || gso_ctx == NULL ||
> >>  			nb_pkts_out < 1)
> >>  		return -EINVAL;
> >>
> >> -	pkt->ol_flags &= (~PKT_TX_TCP_SEG);
> >> -	pkts_out[0] = pkt;
> >> +	if ((gso_ctx->gso_size >= pkt->pkt_len) || (gso_ctx->gso_types &
> >> +				DEV_TX_OFFLOAD_TCP_TSO) !=
> >> +			gso_ctx->gso_types) {
> >> +		pkt->ol_flags &= (~PKT_TX_TCP_SEG);
> >> +		pkts_out[0] = pkt;
> >> +		return 1;
> >> +	}
> >> +
> >> +	direct_pool = gso_ctx->direct_pool;
> >> +	indirect_pool = gso_ctx->indirect_pool;
> >> +	gso_size = gso_ctx->gso_size;
> >> +	ipid_delta = (gso_ctx->ipid_flag != RTE_GSO_IPID_FIXED);
> >> +	ol_flags = pkt->ol_flags;
> >> +
> >> +	if (IS_IPV4_TCP(pkt->ol_flags)) {
> >> +		pkt->ol_flags &= (~PKT_TX_TCP_SEG);
> >> +		ret = gso_tcp4_segment(pkt, gso_size, ipid_delta,
> >> +				direct_pool, indirect_pool,
> >> +				pkts_out, nb_pkts_out);
> >> +	} else {
> >> +		pkt->ol_flags &= (~PKT_TX_TCP_SEG);
> >
> >Not sure why do you clean this flag if you don't support that packet type
> >and no action was perfomed?
> >Suppose you have a mix ipv4 and ipv6 packets - gso lib would do ipv4 and
> >someone else
> >(HW?) can do ipv4 segmentation.
> 
> I can't say for definite, since I didn't implement this change. However, I can only presume that the assumption here is that since
> segmentation is being done in S/W that the underlying H/W does not support TSO.
> Since the underlying HW can't segment the packet in HW, we should clear the flag; otherwise, if an mbuf marked for TCP segmentation is
> passed to the driver of a NIC that does not support/understand that feature, the behavior is undefined.
> Is this a fair assumption in your opinion, or is it the case that the packet would simply be transmitted un-segmented in that case, and so we
> shouldn't clear the flag?

Yes, I think if we shouldn't clear the flag if we didn't do any segmentation (we just encounter a packet type that we don't support).
Konstantin

> 
> Thanks again,
> Mark
> 
> >BTW, did you notice that building of shared target fails?
> >Konstantin
> 
> I didn't, but I'll take a look right now - thanks for the catch!
> 
> >
> >
> >> +		pkts_out[0] = pkt;
> >> +		RTE_LOG(WARNING, GSO, "Unsupported packet type\n");
> >> +		return 1;
> >> +	}
> >> +
> >> +	if (ret > 1) {
> >> +		pkt_seg = pkt;
> >> +		while (pkt_seg) {
> >> +			rte_mbuf_refcnt_update(pkt_seg, -1);
> >> +			pkt_seg = pkt_seg->next;
> >> +		}
> >> +	} else if (ret < 0) {
> >> +		/* Revert the ol_flags in the event of failure. */
> >> +		pkt->ol_flags = ol_flags;
> >> +	}
> >>
> >> -	return 1;
> >> +	return ret;
> >>  }
> >> --
> >> 1.9.3



More information about the dev mailing list