sfc: Replace tso_state::full_packet_space with ip_base_len

We only use tso_state::full_packet_space to calculate the IPv4 tot_len
or IPv6 payload_len, not to set tso_state::packet_space.  Replace it
with an ip_base_len field holding the value of tot_len or payload_len
before including the TCP payload, which is much more useful when
constructing the new headers.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
index 61bc0ed..d9dbebc 100644 (file)
--- a/drivers/net/ethernet/sfc/tx.c
+++ b/drivers/net/ethernet/sfc/tx.c
@@ -631,7 +631,7 @@ void efx_remove_tx_queue(struct efx_tx_queue *tx_queue)
  * @dma_flags: TX buffer flags for DMA mapping - %EFX_TX_BUF_MAP_SINGLE or 0
  * @protocol: Network protocol (after any VLAN header)
  * @header_len: Number of bytes of header
- * @full_packet_size: Number of bytes to put in each outgoing segment
+ * @ip_base_len: IPv4 tot_len or IPv6 payload_len, before TCP payload
  *
  * The state used during segmentation.  It is put into this data structure
  * just to make it easy to pass into inline functions.
@@ -652,7 +652,7 @@ struct tso_state {
 
        __be16 protocol;
        unsigned header_len;
-       int full_packet_size;
+       unsigned int ip_base_len;
 };
 
 
@@ -830,12 +830,14 @@ static void tso_start(struct tso_state *st, const struct sk_buff *skb)
         */
        st->header_len = ((tcp_hdr(skb)->doff << 2u)
                          + PTR_DIFF(tcp_hdr(skb), skb->data));
-       st->full_packet_size = st->header_len + skb_shinfo(skb)->gso_size;
 
-       if (st->protocol == htons(ETH_P_IP))
+       if (st->protocol == htons(ETH_P_IP)) {
+               st->ip_base_len = st->header_len - ETH_HDR_LEN(skb);
                st->ipv4_id = ntohs(ip_hdr(skb)->id);
-       else
+       } else {
+               st->ip_base_len = tcp_hdr(skb)->doff << 2u;
                st->ipv4_id = 0;
+       }
        st->seqnum = ntohl(tcp_hdr(skb)->seq);
 
        EFX_BUG_ON_PARANOID(tcp_hdr(skb)->urg);
@@ -966,15 +968,16 @@ static int tso_start_new_packet(struct efx_tx_queue *tx_queue,
        st->seqnum += skb_shinfo(skb)->gso_size;
        if (st->out_len > skb_shinfo(skb)->gso_size) {
                /* This packet will not finish the TSO burst. */
-               ip_length = st->full_packet_size - ETH_HDR_LEN(skb);
+               st->packet_space = skb_shinfo(skb)->gso_size;
                tsoh_th->fin = 0;
                tsoh_th->psh = 0;
        } else {
                /* This packet will be the last in the TSO burst. */
-               ip_length = st->header_len - ETH_HDR_LEN(skb) + st->out_len;
+               st->packet_space = st->out_len;
                tsoh_th->fin = tcp_hdr(skb)->fin;
                tsoh_th->psh = tcp_hdr(skb)->psh;
        }
+       ip_length = st->ip_base_len + st->packet_space;
 
        if (st->protocol == htons(ETH_P_IP)) {
                struct iphdr *tsoh_iph =
@@ -989,14 +992,13 @@ static int tso_start_new_packet(struct efx_tx_queue *tx_queue,
                struct ipv6hdr *tsoh_iph =
                        (struct ipv6hdr *)(header + SKB_IPV6_OFF(skb));
 
-               tsoh_iph->payload_len = htons(ip_length - sizeof(*tsoh_iph));
+               tsoh_iph->payload_len = htons(ip_length);
        }
 
        rc = efx_tso_put_header(tx_queue, buffer, header);
        if (unlikely(rc))
                return rc;
 
-       st->packet_space = skb_shinfo(skb)->gso_size;
        ++tx_queue->tso_packets;
 
        return 0;