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skbuff: in skb_segment, call zerocopy functions once per nskb

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This is a net-next follow-up to commit 268b790679 ("skbuff: orphan
frags before zerocopy clone"), which fixed a bug in net, but added a
call to skb_zerocopy_clone at each frag to do so.

When segmenting skbs with user frags, either the user frags must be
replaced with private copies and uarg released, or the uarg must have
its refcount increased for each new skb.

skb_orphan_frags does the first, except for cases that can handle
reference counting. skb_zerocopy_clone then does the second.

Call these once per nskb, instead of once per frag.

That is, in the common case. With a frag list, also refresh when the
origin skb (frag_skb) changes.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Willem de Bruijn 2017-12-22 19:00:17 -05:00 committed by David S. Miller
parent 1f119f9038
commit bf5c25d608
1 changed files with 9 additions and 5 deletions
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14
net/core/skbuff.c
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@ -3656,6 +3656,10 @@ normal:
skb_shinfo(nskb)->tx_flags |= skb_shinfo(head_skb)->tx_flags &
SKBTX_SHARED_FRAG;
if (skb_orphan_frags(frag_skb, GFP_ATOMIC) ||
skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
goto err;
while (pos < offset + len) {
if (i >= nfrags) {
BUG_ON(skb_headlen(list_skb));
@ -3667,6 +3671,11 @@ normal:
BUG_ON(!nfrags);
if (skb_orphan_frags(frag_skb, GFP_ATOMIC) ||
skb_zerocopy_clone(nskb, frag_skb,
GFP_ATOMIC))
goto err;
list_skb = list_skb->next;
}
@ -3678,11 +3687,6 @@ normal:
goto err;
}
if (unlikely(skb_orphan_frags(frag_skb, GFP_ATOMIC)))
goto err;
if (skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
goto err;
*nskb_frag = *frag;
__skb_frag_ref(nskb_frag);
size = skb_frag_size(nskb_frag);