net/core/tso.c

   1 #include <linux/export.h>
   2 #include <net/ip.h>
   3 #include <net/tso.h>
   4
   5 /* Calculate expected number of TX descriptors */
   6 int tso_count_descs(struct sk_buff *skb)
   7 {
   8         /* The Marvell Way */
   9         return skb_shinfo(skb)->gso_segs * 2 + skb_shinfo(skb)->nr_frags;
  10 }
  11 EXPORT_SYMBOL(tso_count_descs);
  12
  13 void tso_build_hdr(struct sk_buff *skb, char *hdr, struct tso_t *tso,
  14                    int size, bool is_last)
  15 {
  16         struct iphdr *iph;
  17         struct tcphdr *tcph;
  18         int hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
  19         int mac_hdr_len = skb_network_offset(skb);
  20
  21         memcpy(hdr, skb->data, hdr_len);
  22         iph = (struct iphdr *)(hdr + mac_hdr_len);
  23         iph->id = htons(tso->ip_id);
  24         iph->tot_len = htons(size + hdr_len - mac_hdr_len);
  25         tcph = (struct tcphdr *)(hdr + skb_transport_offset(skb));
  26         tcph->seq = htonl(tso->tcp_seq);
  27         tso->ip_id++;
  28
  29         if (!is_last) {
  30                 /* Clear all special flags for not last packet */
  31                 tcph->psh = 0;
  32                 tcph->fin = 0;
  33                 tcph->rst = 0;
  34         }
  35 }
  36 EXPORT_SYMBOL(tso_build_hdr);
  37
  38 void tso_build_data(struct sk_buff *skb, struct tso_t *tso, int size)
  39 {
  40         tso->tcp_seq += size;
  41         tso->size -= size;
  42         tso->data += size;
  43
  44         if ((tso->size == 0) &&
  45             (tso->next_frag_idx < skb_shinfo(skb)->nr_frags)) {
  46                 skb_frag_t *frag = &skb_shinfo(skb)->frags[tso->next_frag_idx];
  47
  48                 /* Move to next segment */
  49                 tso->size = frag->size;
  50                 tso->data = page_address(frag->page.p) + frag->page_offset;
  51                 tso->next_frag_idx++;
  52         }
  53 }
  54 EXPORT_SYMBOL(tso_build_data);
  55
  56 void tso_start(struct sk_buff *skb, struct tso_t *tso)
  57 {
  58         int hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
  59
  60         tso->ip_id = ntohs(ip_hdr(skb)->id);
  61         tso->tcp_seq = ntohl(tcp_hdr(skb)->seq);
  62         tso->next_frag_idx = 0;
  63
  64         /* Build first data */
  65         tso->size = skb_headlen(skb) - hdr_len;
  66         tso->data = skb->data + hdr_len;
  67         if ((tso->size == 0) &&
  68             (tso->next_frag_idx < skb_shinfo(skb)->nr_frags)) {
  69                 skb_frag_t *frag = &skb_shinfo(skb)->frags[tso->next_frag_idx];
  70
  71                 /* Move to next segment */
  72                 tso->size = frag->size;
  73                 tso->data = page_address(frag->page.p) + frag->page_offset;
  74                 tso->next_frag_idx++;
  75         }
  76 }
  77 EXPORT_SYMBOL(tso_start);