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

Signed-off-by: Thomas Graf <tg...@suug.ch>
---
 include/linux/skbuff.h               |  2 ++
 net/core/skbuff.c                    | 46 +++++++++++++++++++++++++++++++++++
 net/netfilter/nfnetlink_queue_core.c | 47 +-----------------------------------
 3 files changed, 49 insertions(+), 46 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 2e0ced1..ff2cbe8 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2478,6 +2478,8 @@ extern int             skb_splice_bits(struct sk_buff 
*skb,
                                                unsigned int len,
                                                unsigned int flags);
 extern void           skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
+extern void           skb_zerocopy(struct sk_buff *to, const struct sk_buff 
*from,
+                                   int len, int hlen);
 extern void           skb_split(struct sk_buff *skb,
                                 struct sk_buff *skb1, const u32 len);
 extern int            skb_shift(struct sk_buff *tgt, struct sk_buff *skb,
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index d629891..cb60bf6 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2118,6 +2118,52 @@ void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 
*to)
 }
 EXPORT_SYMBOL(skb_copy_and_csum_dev);
 
+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;
+
+       /* 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);
+
 /**
  *     skb_dequeue - remove from the head of the queue
  *     @list: list to dequeue from
diff --git a/net/netfilter/nfnetlink_queue_core.c 
b/net/netfilter/nfnetlink_queue_core.c
index 2e0e835..7ac9dba 100644
--- a/net/netfilter/nfnetlink_queue_core.c
+++ b/net/netfilter/nfnetlink_queue_core.c
@@ -227,51 +227,6 @@ 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)
 {
        __u32 flags = 0;
@@ -481,7 +436,7 @@ nfqnl_build_packet_message(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;
-- 
1.7.11.7

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