[ 60/61] net: splice: fix __splice_segment()

Greg Kroah-Hartman
2013-02-12T20:36:31Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit bc9540c637c3d8712ccbf9dcf28621f380ed5e64 ]

commit 9ca1b22d6d2 (net: splice: avoid high order page splitting)
forgot that skb->head could need a copy into several page frags.

This could be the case for loopback traffic mostly.

Also remove now useless skb argument from linear_to_page()
and __splice_segment() prototypes.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/skbuff.c | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)

--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1620,7 +1620,7 @@ static void sock_spd_release(struct spli

static struct page *linear_to_page(struct page *page, unsigned int *len,
unsigned int *offset,
- struct sk_buff *skb, struct sock *sk)
+ struct sock *sk)
{
struct page_frag *pfrag = sk_page_frag(sk);

@@ -1653,14 +1653,14 @@ static bool spd_can_coalesce(const struc
static bool spd_fill_page(struct splice_pipe_desc *spd,
struct pipe_inode_info *pipe, struct page *page,
unsigned int *len, unsigned int offset,
- struct sk_buff *skb, bool linear,
+ bool linear,
struct sock *sk)
{
if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
return true;

if (linear) {
- page = linear_to_page(page, len, &offset, skb, sk);
+ page = linear_to_page(page, len, &offset, sk);
if (!page)
return true;
}
@@ -1679,13 +1679,11 @@ static bool spd_fill_page(struct splice_

static bool __splice_segment(struct page *page, unsigned int poff,
unsigned int plen, unsigned int *off,
- unsigned int *len, struct sk_buff *skb,
+ unsigned int *len,
struct splice_pipe_desc *spd, bool linear,
struct sock *sk,
struct pipe_inode_info *pipe)
{
- unsigned int flen;
-
if (!*len)
return true;

@@ -1700,12 +1698,16 @@ static bool __splice_segment(struct page
plen -= *off;
*off = 0;

- flen = min(*len, plen);
-
- if (spd_fill_page(spd, pipe, page, &flen, poff, skb, linear, sk))
- return true;
+ do {
+ unsigned int flen = min(*len, plen);

- *len -= flen;
+ if (spd_fill_page(spd, pipe, page, &flen, poff,
+ linear, sk))
+ return true;
+ poff += flen;
+ plen -= flen;
+ *len -= flen;
+ } while (*len && plen);

return false;
}
@@ -1728,7 +1730,7 @@ static bool __skb_splice_bits(struct sk_
if (__splice_segment(virt_to_page(skb->data),
(unsigned long) skb->data & (PAGE_SIZE - 1),
skb_headlen(skb),
- offset, len, skb, spd,
+ offset, len, spd,
skb_head_is_locked(skb),
sk, pipe))
return true;
@@ -1741,7 +1743,7 @@ static bool __skb_splice_bits(struct sk_

if (__splice_segment(skb_frag_page(f),
f->page_offset, skb_frag_size(f),
- offset, len, skb, spd, false, sk, pipe))
+ offset, len, spd, false, sk, pipe))
return true;
}