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authorEric Dumazet <eric.dumazet@gmail.com>2010-09-01 00:50:51 +0000
committerDavid S. Miller <davem@davemloft.net>2010-09-01 19:17:35 -0700
commit3d3be4333fdf6faa080947b331a6a19bce1a4f57 (patch)
treedd27c40e1fa650369eb5865c4c47dc0001bcc6af /net
parent87f94b4e91dc042620c527f3c30c37e5127ef757 (diff)
gro: fix different skb headrooms
Packets entering GRO might have different headrooms, even for a given flow (because of implementation details in drivers, like copybreak). We cant force drivers to deliver packets with a fixed headroom. 1) fix skb_segment() skb_segment() makes the false assumption headrooms of fragments are same than the head. When CHECKSUM_PARTIAL is used, this can give csum_start errors, and crash later in skb_copy_and_csum_dev() 2) allocate a minimal skb for head of frag_list skb_gro_receive() uses netdev_alloc_skb(headroom + skb_gro_offset(p)) to allocate a fresh skb. This adds NET_SKB_PAD to a padding already provided by netdevice, depending on various things, like copybreak. Use alloc_skb() to allocate an exact padding, to reduce cache line needs: NET_SKB_PAD + NET_IP_ALIGN bugzilla : https://bugzilla.kernel.org/show_bug.cgi?id=16626 Many thanks to Plamen Petrov, testing many debugging patches ! With help of Jarek Poplawski. Reported-by: Plamen Petrov <pvp-lsts@fs.uni-ruse.bg> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> CC: Jarek Poplawski <jarkao2@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/skbuff.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 3a2513f0d0c3..26396ff67cf9 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2573,6 +2573,10 @@ struct sk_buff *skb_segment(struct sk_buff *skb, int features)
__copy_skb_header(nskb, skb);
nskb->mac_len = skb->mac_len;
+ /* nskb and skb might have different headroom */
+ if (nskb->ip_summed == CHECKSUM_PARTIAL)
+ nskb->csum_start += skb_headroom(nskb) - headroom;
+
skb_reset_mac_header(nskb);
skb_set_network_header(nskb, skb->mac_len);
nskb->transport_header = (nskb->network_header +
@@ -2702,8 +2706,8 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
} else if (skb_gro_len(p) != pinfo->gso_size)
return -E2BIG;
- headroom = skb_headroom(p);
- nskb = netdev_alloc_skb(p->dev, headroom + skb_gro_offset(p));
+ headroom = NET_SKB_PAD + NET_IP_ALIGN;
+ nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC);
if (unlikely(!nskb))
return -ENOMEM;