diff options
author | Alexander Duyck <alexander.h.duyck@intel.com> | 2012-05-02 14:18:42 -0400 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2012-05-03 01:34:37 -0400 |
commit | 2996d31f9f292cce67cd9105dc0a4a5ee43d2f14 (patch) | |
tree | 4368e35e13d083a40530c88de554de8d88c0aa41 /net/core/skbuff.c | |
parent | b081f85c2977b1cbb6e635d53d9512f1ef985972 (diff) |
net: Stop decapitating clones that have a head_frag
This change is meant ot prevent stealing the skb->head to use as a page in
the event that the skb->head was cloned. This allows the other clones to
track each other via shinfo->dataref.
Without this we break down to two methods for tracking the reference count,
one being dataref, the other being the page count. As a result it becomes
difficult to track how many references there are to skb->head.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/skbuff.c')
-rw-r--r-- | net/core/skbuff.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 52ba2b5e803d..9e8caa0c4f72 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c | |||
@@ -1699,17 +1699,18 @@ static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe, | |||
1699 | struct splice_pipe_desc *spd, struct sock *sk) | 1699 | struct splice_pipe_desc *spd, struct sock *sk) |
1700 | { | 1700 | { |
1701 | int seg; | 1701 | int seg; |
1702 | bool head_is_linear = !skb->head_frag; | 1702 | bool head_is_locked = !skb->head_frag || skb_cloned(skb); |
1703 | 1703 | ||
1704 | /* map the linear part : | 1704 | /* map the linear part : |
1705 | * If skb->head_frag is set, this 'linear' part is backed | 1705 | * If skb->head_frag is set, this 'linear' part is backed by a |
1706 | * by a fragment, and we can avoid a copy. | 1706 | * fragment, and if the head is not shared with any clones then |
1707 | * we can avoid a copy since we own the head portion of this page. | ||
1707 | */ | 1708 | */ |
1708 | if (__splice_segment(virt_to_page(skb->data), | 1709 | if (__splice_segment(virt_to_page(skb->data), |
1709 | (unsigned long) skb->data & (PAGE_SIZE - 1), | 1710 | (unsigned long) skb->data & (PAGE_SIZE - 1), |
1710 | skb_headlen(skb), | 1711 | skb_headlen(skb), |
1711 | offset, len, skb, spd, | 1712 | offset, len, skb, spd, |
1712 | head_is_linear, | 1713 | head_is_locked, |
1713 | sk, pipe)) | 1714 | sk, pipe)) |
1714 | return true; | 1715 | return true; |
1715 | 1716 | ||