2 * Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
3 * Portions based on net/core/datagram.c and copyrighted by their authors.
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License as published by the Free
7 * Software Foundation; either version 2 of the License, or (at your option)
10 * This program is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc., 59
17 * Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19 * The full GNU General Public License is included in this distribution in the
20 * file called COPYING.
24 * This code allows the net stack to make use of a DMA engine for
25 * skb to iovec copies.
28 #include <linux/dmaengine.h>
29 #include <linux/socket.h>
31 #include <net/netdma.h>
33 #define NET_DMA_DEFAULT_COPYBREAK 4096
35 int sysctl_tcp_dma_copybreak = NET_DMA_DEFAULT_COPYBREAK;
36 EXPORT_SYMBOL(sysctl_tcp_dma_copybreak);
39 * dma_skb_copy_datagram_iovec - Copy a datagram to an iovec.
40 * @skb - buffer to copy
41 * @offset - offset in the buffer to start copying from
42 * @iovec - io vector to copy to
43 * @len - amount of data to copy from buffer to iovec
44 * @pinned_list - locked iovec buffer data
46 * Note: the iovec is modified during the copy.
48 int dma_skb_copy_datagram_iovec(struct dma_chan *chan,
49 struct sk_buff *skb, int offset, struct iovec *to,
50 size_t len, struct dma_pinned_list *pinned_list)
52 int start = skb_headlen(skb);
53 int i, copy = start - offset;
54 dma_cookie_t cookie = 0;
60 cookie = dma_memcpy_to_iovec(chan, to, pinned_list,
61 skb->data + offset, copy);
70 /* Copy paged appendix. Hmm... why does this look so complicated? */
71 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
74 WARN_ON(start > offset + len);
76 end = start + skb_shinfo(skb)->frags[i].size;
79 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
80 struct page *page = frag->page;
85 cookie = dma_memcpy_pg_to_iovec(chan, to, pinned_list, page,
86 frag->page_offset + offset - start, copy);
97 if (skb_shinfo(skb)->frag_list) {
98 struct sk_buff *list = skb_shinfo(skb)->frag_list;
100 for (; list; list = list->next) {
103 WARN_ON(start > offset + len);
105 end = start + list->len;
110 cookie = dma_skb_copy_datagram_iovec(chan, list,
111 offset - start, to, copy,
126 skb->dma_cookie = cookie;