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>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index e8a6860128d47d6178be826e51512faa985f4e13..d52fe4bd573fa39efc182bea04da14b9cc0f7923 100644 (file)
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -871,8 +871,10 @@ 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,
@@ -890,7 +892,7 @@ 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) {
@@ -1119,7 +1121,8 @@ 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;