| From 3d3be4333fdf6faa080947b331a6a19bce1a4f57 Mon Sep 17 00:00:00 2001 |
| From: Eric Dumazet <eric.dumazet@gmail.com> |
| Date: Wed, 1 Sep 2010 00:50:51 +0000 |
| Subject: gro: fix different skb headrooms |
| |
| From: Eric Dumazet <eric.dumazet@gmail.com> |
| |
| commit 3d3be4333fdf6faa080947b331a6a19bce1a4f57 upstream. |
| |
| 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> |
| Cc: Ben Hutchings <bhutchings@solarflare.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| net/core/skbuff.c | 8 ++++++-- |
| 1 file changed, 6 insertions(+), 2 deletions(-) |
| |
| --- a/net/core/skbuff.c |
| +++ b/net/core/skbuff.c |
| @@ -2578,6 +2578,10 @@ struct sk_buff *skb_segment(struct sk_bu |
| __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 + |
| @@ -2707,8 +2711,8 @@ int skb_gro_receive(struct sk_buff **hea |
| } 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; |
| |