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Message-ID: <20190829163319.0f4e8707@cakuba.netronome.com>
Date: Thu, 29 Aug 2019 16:33:19 -0700
From: Jakub Kicinski <jakub.kicinski@...ronome.com>
To: Shannon Nelson <snelson@...sando.io>
Cc: netdev@...r.kernel.org, davem@...emloft.net
Subject: Re: [PATCH v6 net-next 15/19] ionic: Add Tx and Rx handling
On Thu, 29 Aug 2019 11:27:16 -0700, Shannon Nelson wrote:
> +static int ionic_tx_tso(struct ionic_queue *q, struct sk_buff *skb)
> +{
> + struct ionic_tx_stats *stats = q_to_tx_stats(q);
> + struct ionic_desc_info *abort = q->head;
> + struct device *dev = q->lif->ionic->dev;
> + struct ionic_desc_info *rewind = abort;
> + struct ionic_txq_sg_elem *elem;
> + struct ionic_txq_desc *desc;
> + unsigned int frag_left = 0;
> + unsigned int offset = 0;
> + unsigned int len_left;
> + dma_addr_t desc_addr;
> + unsigned int hdrlen;
> + unsigned int nfrags;
> + unsigned int seglen;
> + u64 total_bytes = 0;
> + u64 total_pkts = 0;
> + unsigned int left;
> + unsigned int len;
> + unsigned int mss;
> + skb_frag_t *frag;
> + bool start, done;
> + bool outer_csum;
> + bool has_vlan;
> + u16 desc_len;
> + u8 desc_nsge;
> + u16 vlan_tci;
> + bool encap;
> + int err;
> +
> + mss = skb_shinfo(skb)->gso_size;
> + nfrags = skb_shinfo(skb)->nr_frags;
> + len_left = skb->len - skb_headlen(skb);
> + outer_csum = (skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM) ||
> + (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM);
> + has_vlan = !!skb_vlan_tag_present(skb);
> + vlan_tci = skb_vlan_tag_get(skb);
> + encap = skb->encapsulation;
> +
> + /* Preload inner-most TCP csum field with IP pseudo hdr
> + * calculated with IP length set to zero. HW will later
> + * add in length to each TCP segment resulting from the TSO.
> + */
> +
> + if (encap)
> + err = ionic_tx_tcp_inner_pseudo_csum(skb);
> + else
> + err = ionic_tx_tcp_pseudo_csum(skb);
> + if (err)
> + return err;
> +
> + if (encap)
> + hdrlen = skb_inner_transport_header(skb) - skb->data +
> + inner_tcp_hdrlen(skb);
> + else
> + hdrlen = skb_transport_offset(skb) + tcp_hdrlen(skb);
> +
> + seglen = hdrlen + mss;
> + left = skb_headlen(skb);
> +
> + desc = ionic_tx_tso_next(q, &elem);
> + start = true;
> +
> + /* Chop skb->data up into desc segments */
> +
> + while (left > 0) {
> + len = min(seglen, left);
> + frag_left = seglen - len;
> + desc_addr = ionic_tx_map_single(q, skb->data + offset, len);
> + if (dma_mapping_error(dev, desc_addr))
> + goto err_out_abort;
> + desc_len = len;
> + desc_nsge = 0;
> + left -= len;
> + offset += len;
> + if (nfrags > 0 && frag_left > 0)
> + continue;
> + done = (nfrags == 0 && left == 0);
> + ionic_tx_tso_post(q, desc, skb,
> + desc_addr, desc_nsge, desc_len,
> + hdrlen, mss,
> + outer_csum,
> + vlan_tci, has_vlan,
> + start, done);
> + total_pkts++;
> + total_bytes += start ? len : len + hdrlen;
> + desc = ionic_tx_tso_next(q, &elem);
> + start = false;
> + seglen = mss;
> + }
> +
> + /* Chop skb frags into desc segments */
> +
> + for (frag = skb_shinfo(skb)->frags; len_left; frag++) {
> + offset = 0;
> + left = skb_frag_size(frag);
> + len_left -= left;
> + nfrags--;
> + stats->frags++;
> +
> + while (left > 0) {
> + if (frag_left > 0) {
> + len = min(frag_left, left);
> + frag_left -= len;
> + elem->addr =
> + cpu_to_le64(ionic_tx_map_frag(q, frag,
> + offset, len));
> + if (dma_mapping_error(dev, elem->addr))
> + goto err_out_abort;
> + elem->len = cpu_to_le16(len);
> + elem++;
> + desc_nsge++;
> + left -= len;
> + offset += len;
> + if (nfrags > 0 && frag_left > 0)
> + continue;
> + done = (nfrags == 0 && left == 0);
> + ionic_tx_tso_post(q, desc, skb, desc_addr,
> + desc_nsge, desc_len,
> + hdrlen, mss, outer_csum,
> + vlan_tci, has_vlan,
> + start, done);
> + total_pkts++;
> + total_bytes += start ? len : len + hdrlen;
> + desc = ionic_tx_tso_next(q, &elem);
> + start = false;
> + } else {
> + len = min(mss, left);
> + frag_left = mss - len;
> + desc_addr = ionic_tx_map_frag(q, frag,
> + offset, len);
> + if (dma_mapping_error(dev, desc_addr))
> + goto err_out_abort;
> + desc_len = len;
> + desc_nsge = 0;
> + left -= len;
> + offset += len;
> + if (nfrags > 0 && frag_left > 0)
> + continue;
> + done = (nfrags == 0 && left == 0);
> + ionic_tx_tso_post(q, desc, skb, desc_addr,
> + desc_nsge, desc_len,
> + hdrlen, mss, outer_csum,
> + vlan_tci, has_vlan,
> + start, done);
> + total_pkts++;
> + total_bytes += start ? len : len + hdrlen;
> + desc = ionic_tx_tso_next(q, &elem);
> + start = false;
> + }
> + }
> + }
> +
> + stats->pkts += total_pkts;
> + stats->bytes += total_bytes;
> + stats->tso++;
> +
> + return 0;
> +
> +err_out_abort:
> + while (rewind->desc != q->head->desc) {
> + ionic_tx_clean(q, rewind, NULL, NULL);
> + rewind = rewind->next;
> + }
> + q->head = abort;
> +
> + return -ENOMEM;
> +}
There's definitely a function for helping drivers which can't do full
TSO slice up the packet, but I can't find it now 😫😫
Eric would definitely know.
Did you have a look? Would it be useful here?
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