Commit bf5c25d6 authored Dec 22, 2017 by Willem de Bruijn Committed by David S. Miller Dec 27, 2017

skbuff: in skb_segment, call zerocopy functions once per nskb



This is a net-next follow-up to commit 268b7906 ("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>

parent 1f119f90

net/core/skbuff.c

+9 −5

Original line number	Diff line number	Diff line
		@@ -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);

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