gro: New frags interface to avoid copying shinfo

It turns out that copying a 16-byte area at ~800k times a second
can be really expensive :) This patch redesigns the frags GRO
interface to avoid copying that area twice.

The two disciples of the frags interface have been converted.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 18 insertions, 8 deletions

diff --git a/drivers/net/sfc/rx.c b/drivers/net/sfc/rx.c
index 66d7fe3db3e6..01f9432c31ef 100644
--- a/drivers/net/sfc/rx.c
+++ b/drivers/net/sfc/rx.c
@@ -450,17 +450,27 @@ static void efx_rx_packet_lro(struct efx_channel *channel,
 
         /* Pass the skb/page into the LRO engine */
         if (rx_buf->page) {
-                struct napi_gro_fraginfo info;
+                struct sk_buff *skb = napi_get_frags(napi);
 
-                info.frags[0].page = rx_buf->page;
-                info.frags[0].page_offset = efx_rx_buf_offset(rx_buf);
-                info.frags[0].size = rx_buf->len;
-                info.nr_frags = 1;
-                info.ip_summed = CHECKSUM_UNNECESSARY;
-                info.len = rx_buf->len;
+                if (!skb) {
+                        put_page(rx_buf->page);
+                        goto out;
+                }
+
+                skb_shinfo(skb)->frags[0].page = rx_buf->page;
+                skb_shinfo(skb)->frags[0].page_offset =
+                        efx_rx_buf_offset(rx_buf);
+                skb_shinfo(skb)->frags[0].size = rx_buf->len;
+                skb_shinfo(skb)->nr_frags = 1;
+
+                skb->len = rx_buf->len;
+                skb->data_len = rx_buf->len;
+                skb->truesize += rx_buf->len;
+                skb->ip_summed = CHECKSUM_UNNECESSARY;
 
-                napi_gro_frags(napi, &info);
+                napi_gro_frags(napi);
 
+out:
                 EFX_BUG_ON_PARANOID(rx_buf->skb);
                 rx_buf->page = NULL;
         } else {