udp: paged allocation with gso

When sending large datagrams that are later segmented, store data in
page frags to avoid copying from linear in skb_segment.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 4 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index da4abbee10f7..f2338e40c37d 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -878,11 +878,13 @@ static int __ip_append_data(struct sock *sk,
         struct rtable *rt = (struct rtable *)cork->dst;
         unsigned int wmem_alloc_delta = 0;
         u32 tskey = 0;
+        bool paged;
 
         skb = skb_peek_tail(queue);
 
         exthdrlen = !skb ? rt->dst.header_len : 0;
         mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
+        paged = !!cork->gso_size;
 
         if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
             sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
@@ -934,6 +936,7 @@ static int __ip_append_data(struct sock *sk,
                         unsigned int fraglen;
                         unsigned int fraggap;
                         unsigned int alloclen;
+                        unsigned int pagedlen = 0;
                         struct sk_buff *skb_prev;
 alloc_new_skb:
                         skb_prev = skb;
@@ -954,8 +957,12 @@ alloc_new_skb:
                         if ((flags & MSG_MORE) &&
                             !(rt->dst.dev->features&NETIF_F_SG))
                                 alloclen = mtu;
-                        else
+                        else if (!paged)
                                 alloclen = fraglen;
+                        else {
+                                alloclen = min_t(int, fraglen, MAX_HEADER);
+                                pagedlen = fraglen - alloclen;
+                        }
 
                         alloclen += exthdrlen;
 
@@ -999,7 +1006,7 @@ alloc_new_skb:
                         /*
                          *      Find where to start putting bytes.
                          */
-                        data = skb_put(skb, fraglen + exthdrlen);
+                        data = skb_put(skb, fraglen + exthdrlen - pagedlen);
                         skb_set_network_header(skb, exthdrlen);
                         skb->transport_header = (skb->network_header +
                                                  fragheaderlen);
@@ -1015,7 +1022,7 @@ alloc_new_skb:
                                 pskb_trim_unique(skb_prev, maxfraglen);
                         }
 
-                        copy = datalen - transhdrlen - fraggap;
+                        copy = datalen - transhdrlen - fraggap - pagedlen;
                         if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
                                 err = -EFAULT;
                                 kfree_skb(skb);
@@ -1023,7 +1030,7 @@ alloc_new_skb:
                         }
 
                         offset += copy;
-                        length -= datalen - fraggap;
+                        length -= copy + transhdrlen;
                         transhdrlen = 0;
                         exthdrlen = 0;
                         csummode = CHECKSUM_NONE;