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    Subject[PATCH NET v2 7/7] bpf: use skb_expand_head in bpf_out_neigh_v4/6
    Date
    Unlike skb_realloc_headroom, new helper skb_expand_head
    does not allocate a new skb if possible.

    Additionally this patch replaces commonly used dereferencing with variables.

    Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
    ---
    net/core/filter.c | 27 +++++----------------------
    1 file changed, 5 insertions(+), 22 deletions(-)

    diff --git a/net/core/filter.c b/net/core/filter.c
    index 65ab4e2..25a6950 100644
    --- a/net/core/filter.c
    +++ b/net/core/filter.c
    @@ -2179,17 +2179,9 @@ static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb,
    skb->tstamp = 0;

    if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
    - struct sk_buff *skb2;
    -
    - skb2 = skb_realloc_headroom(skb, hh_len);
    - if (unlikely(!skb2)) {
    - kfree_skb(skb);
    + skb = skb_expand_head(skb, hh_len);
    + if (!skb)
    return -ENOMEM;
    - }
    - if (skb->sk)
    - skb_set_owner_w(skb2, skb->sk);
    - consume_skb(skb);
    - skb = skb2;
    }

    rcu_read_lock_bh();
    @@ -2213,8 +2205,7 @@ static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb,
    }
    rcu_read_unlock_bh();
    if (dst)
    - IP6_INC_STATS(dev_net(dst->dev),
    - ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
    + IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
    out_drop:
    kfree_skb(skb);
    return -ENETDOWN;
    @@ -2286,17 +2277,9 @@ static int bpf_out_neigh_v4(struct net *net, struct sk_buff *skb,
    skb->tstamp = 0;

    if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
    - struct sk_buff *skb2;
    -
    - skb2 = skb_realloc_headroom(skb, hh_len);
    - if (unlikely(!skb2)) {
    - kfree_skb(skb);
    + skb = skb_expand_head(skb, hh_len);
    + if (!skb)
    return -ENOMEM;
    - }
    - if (skb->sk)
    - skb_set_owner_w(skb2, skb->sk);
    - consume_skb(skb);
    - skb = skb2;
    }

    rcu_read_lock_bh();
    --
    1.8.3.1
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