udp: Fix bogus UFO packet generation

commit 26cde9f7e2747b6d254b704594eed87ab959afa5 upstream.

It has been reported that the new UFO software fallback path
fails under certain conditions with NFS.  I tracked the problem
down to the generation of UFO packets that are smaller than the
MTU.  The software fallback path simply discards these packets.

This patch fixes the problem by not generating such packets on
the UFO path.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index b29672117493339efbc8143c3c6d4f7193939156..a6e5a0885f293a89e772780b12d0ad304b6b8850 100644 (file)
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -870,8 +870,10 @@ int ip_append_data(struct sock *sk,
            !exthdrlen)
                csummode = CHECKSUM_PARTIAL;
 
+       skb = skb_peek_tail(&sk->sk_write_queue);
+
        inet->cork.length += length;
-       if (((length> mtu) || !skb_queue_empty(&sk->sk_write_queue)) &&
+       if (((length > mtu) || (skb && skb_is_gso(skb))) &&
            (sk->sk_protocol == IPPROTO_UDP) &&
            (rt->u.dst.dev->features & NETIF_F_UFO)) {
                err = ip_ufo_append_data(sk, getfrag, from, length, hh_len,
@@ -889,7 +891,7 @@ int ip_append_data(struct sock *sk,
         * adding appropriate IP header.
         */
 
-       if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
+       if (!skb)
                goto alloc_new_skb;
 
        while (length > 0) {
@@ -1118,7 +1120,8 @@ ssize_t   ip_append_page(struct sock *sk, struct page *page,
                return -EINVAL;
 
        inet->cork.length += size;
-       if ((sk->sk_protocol == IPPROTO_UDP) &&
+       if ((size + skb->len > mtu) &&
+           (sk->sk_protocol == IPPROTO_UDP) &&
            (rt->u.dst.dev->features & NETIF_F_UFO)) {
                skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
                skb_shinfo(skb)->gso_type = SKB_GSO_UDP;