From bf5c25d608613eaf4dcdba5a9cac5b2afe67d635 Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Fri, 22 Dec 2017 19:00:17 -0500 Subject: [PATCH] skbuff: in skb_segment, call zerocopy functions once per nskb This is a net-next follow-up to commit 268b79067942 ("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 Signed-off-by: David S. Miller --- net/core/skbuff.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index a3cb0be4c6f3..00b0757830e2 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3656,6 +3656,10 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, 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 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, 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 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, 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); -- GitLab