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net: Export skb_zerocopy() to zerocopy from one skb to another 

Make the skb zerocopy logic written for nfnetlink queue available for
use by other modules.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Reviewed-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jesse Gross <jesse@nicira.com>
This commit is contained in:
Thomas Graf 2013-12-13 15:22:17 +01:00 committed by Jesse Gross
parent 5f03f47c9c
commit af2806f8f9
3 changed files with 92 additions and 55 deletions
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3
include/linux/skbuff.h
View File

@ -2345,6 +2345,9 @@ int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
struct pipe_inode_info *pipe, unsigned int len,
unsigned int flags);
void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
void skb_zerocopy(struct sk_buff *to, const struct sk_buff *from,
int len, int hlen);
void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
void skb_scrub_packet(struct sk_buff *skb, bool xnet);

85
net/core/skbuff.c
View File

@ -2122,6 +2122,91 @@ __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
}
EXPORT_SYMBOL(skb_copy_and_csum_bits);
/**
* skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
* @from: source buffer
*
* Calculates the amount of linear headroom needed in the 'to' skb passed
* into skb_zerocopy().
*/
unsigned int
skb_zerocopy_headlen(const struct sk_buff *from)
{
unsigned int hlen = 0;
if (!from->head_frag ||
skb_headlen(from) < L1_CACHE_BYTES ||
skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
hlen = skb_headlen(from);
if (skb_has_frag_list(from))
hlen = from->len;
return hlen;
}
EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
/**
* skb_zerocopy - Zero copy skb to skb
* @to: destination buffer
* @source: source buffer
* @len: number of bytes to copy from source buffer
* @hlen: size of linear headroom in destination buffer
*
* Copies up to `len` bytes from `from` to `to` by creating references
* to the frags in the source buffer.
*
* The `hlen` as calculated by skb_zerocopy_headlen() specifies the
* headroom in the `to` buffer.
*/
void
skb_zerocopy(struct sk_buff *to, const struct sk_buff *from, int len, int hlen)
{
int i, j = 0;
int plen = 0; /* length of skb->head fragment */
struct page *page;
unsigned int offset;
BUG_ON(!from->head_frag && !hlen);
/* dont bother with small payloads */
if (len <= skb_tailroom(to)) {
skb_copy_bits(from, 0, skb_put(to, len), len);
return;
}
if (hlen) {
skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
len -= hlen;
} else {
plen = min_t(int, skb_headlen(from), len);
if (plen) {
page = virt_to_head_page(from->head);
offset = from->data - (unsigned char *)page_address(page);
__skb_fill_page_desc(to, 0, page, offset, plen);
get_page(page);
j = 1;
len -= plen;
}
}
to->truesize += len + plen;
to->len += len + plen;
to->data_len += len + plen;
for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
if (!len)
break;
skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
skb_shinfo(to)->frags[j].size = min_t(int, skb_shinfo(to)->frags[j].size, len);
len -= skb_shinfo(to)->frags[j].size;
skb_frag_ref(to, j);
j++;
}
skb_shinfo(to)->nr_frags = j;
}
EXPORT_SYMBOL_GPL(skb_zerocopy);
void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
{
__wsum csum;

59
net/netfilter/nfnetlink_queue_core.c
View File

@ -235,51 +235,6 @@ nfqnl_flush(struct nfqnl_instance *queue, nfqnl_cmpfn cmpfn, unsigned long data)
spin_unlock_bh(&queue->lock);
}
static void
nfqnl_zcopy(struct sk_buff *to, const struct sk_buff *from, int len, int hlen)
{
int i, j = 0;
int plen = 0; /* length of skb->head fragment */
struct page *page;
unsigned int offset;
/* dont bother with small payloads */
if (len <= skb_tailroom(to)) {
skb_copy_bits(from, 0, skb_put(to, len), len);
return;
}
if (hlen) {
skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
len -= hlen;
} else {
plen = min_t(int, skb_headlen(from), len);
if (plen) {
page = virt_to_head_page(from->head);
offset = from->data - (unsigned char *)page_address(page);
__skb_fill_page_desc(to, 0, page, offset, plen);
get_page(page);
j = 1;
len -= plen;
}
}
to->truesize += len + plen;
to->len += len + plen;
to->data_len += len + plen;
for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
if (!len)
break;
skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
skb_shinfo(to)->frags[j].size = min_t(int, skb_shinfo(to)->frags[j].size, len);
len -= skb_shinfo(to)->frags[j].size;
skb_frag_ref(to, j);
j++;
}
skb_shinfo(to)->nr_frags = j;
}
static int
nfqnl_put_packet_info(struct sk_buff *nlskb, struct sk_buff *packet,
bool csum_verify)
@ -304,7 +259,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
{
size_t size;
size_t data_len = 0, cap_len = 0;
int hlen = 0;
unsigned int hlen = 0;
struct sk_buff *skb;
struct nlattr *nla;
struct nfqnl_msg_packet_hdr *pmsg;
@ -356,14 +311,8 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
if (data_len > entskb->len)
data_len = entskb->len;
if (!entskb->head_frag ||
skb_headlen(entskb) < L1_CACHE_BYTES ||
skb_shinfo(entskb)->nr_frags >= MAX_SKB_FRAGS)
hlen = skb_headlen(entskb);
if (skb_has_frag_list(entskb))
hlen = entskb->len;
hlen = min_t(int, data_len, hlen);
hlen = skb_zerocopy_headlen(entskb);
hlen = min_t(unsigned int, hlen, data_len);
size += sizeof(struct nlattr) + hlen;
cap_len = entskb->len;
break;
@ -504,7 +453,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
nla->nla_type = NFQA_PAYLOAD;
nla->nla_len = nla_attr_size(data_len);
nfqnl_zcopy(skb, entskb, data_len, hlen);
skb_zerocopy(skb, entskb, data_len, hlen);
}
nlh->nlmsg_len = skb->len;