blob: 25d717ebc92e9152b77dc678e181551b160c7191 [file] [log] [blame]
Chris Leechde5506e2006-05-23 17:50:37 -07001/*
2 * Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
3 * Portions based on net/core/datagram.c and copyrighted by their authors.
4 *
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)
8 * any later version.
9 *
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
13 * more details.
14 *
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.
18 *
19 * The full GNU General Public License is included in this distribution in the
20 * file called COPYING.
21 */
22
23/*
24 * This code allows the net stack to make use of a DMA engine for
25 * skb to iovec copies.
26 */
27
28#include <linux/dmaengine.h>
29#include <linux/socket.h>
Chris Leechde5506e2006-05-23 17:50:37 -070030#include <net/tcp.h>
Adrian Bunk64d2f082006-07-21 14:49:49 -070031#include <net/netdma.h>
Chris Leechde5506e2006-05-23 17:50:37 -070032
Chris Leech95937822006-05-23 18:02:55 -070033#define NET_DMA_DEFAULT_COPYBREAK 4096
34
35int sysctl_tcp_dma_copybreak = NET_DMA_DEFAULT_COPYBREAK;
Maciej Sosnowski16a37ac2008-07-22 17:30:57 -070036EXPORT_SYMBOL(sysctl_tcp_dma_copybreak);
Chris Leech95937822006-05-23 18:02:55 -070037
Chris Leechde5506e2006-05-23 17:50:37 -070038/**
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
45 *
46 * Note: the iovec is modified during the copy.
47 */
48int 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)
51{
David S. Miller1a028e52007-04-27 15:21:23 -070052 int start = skb_headlen(skb);
53 int i, copy = start - offset;
David S. Miller285e4282009-06-09 00:19:10 -070054 struct sk_buff *frag_iter;
Chris Leechde5506e2006-05-23 17:50:37 -070055 dma_cookie_t cookie = 0;
56
57 /* Copy header. */
58 if (copy > 0) {
59 if (copy > len)
60 copy = len;
61 cookie = dma_memcpy_to_iovec(chan, to, pinned_list,
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090062 skb->data + offset, copy);
Chris Leechde5506e2006-05-23 17:50:37 -070063 if (cookie < 0)
64 goto fault;
65 len -= copy;
66 if (len == 0)
67 goto end;
68 offset += copy;
69 }
70
71 /* Copy paged appendix. Hmm... why does this look so complicated? */
72 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
David S. Miller1a028e52007-04-27 15:21:23 -070073 int end;
Chris Leechde5506e2006-05-23 17:50:37 -070074
Ilpo Järvinen547b7922008-07-25 21:43:18 -070075 WARN_ON(start > offset + len);
David S. Miller1a028e52007-04-27 15:21:23 -070076
77 end = start + skb_shinfo(skb)->frags[i].size;
Chris Leechde5506e2006-05-23 17:50:37 -070078 copy = end - offset;
Brice Goglin7557af22008-06-03 16:07:45 -070079 if (copy > 0) {
Chris Leechde5506e2006-05-23 17:50:37 -070080 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
81 struct page *page = frag->page;
82
83 if (copy > len)
84 copy = len;
85
David S. Miller1a028e52007-04-27 15:21:23 -070086 cookie = dma_memcpy_pg_to_iovec(chan, to, pinned_list, page,
87 frag->page_offset + offset - start, copy);
Chris Leechde5506e2006-05-23 17:50:37 -070088 if (cookie < 0)
89 goto fault;
90 len -= copy;
91 if (len == 0)
92 goto end;
93 offset += copy;
94 }
David S. Miller1a028e52007-04-27 15:21:23 -070095 start = end;
Chris Leechde5506e2006-05-23 17:50:37 -070096 }
97
David S. Miller285e4282009-06-09 00:19:10 -070098 skb_walk_frags(skb, frag_iter) {
99 int end;
Chris Leechde5506e2006-05-23 17:50:37 -0700100
David S. Miller285e4282009-06-09 00:19:10 -0700101 WARN_ON(start > offset + len);
Chris Leechde5506e2006-05-23 17:50:37 -0700102
David S. Miller285e4282009-06-09 00:19:10 -0700103 end = start + frag_iter->len;
104 copy = end - offset;
105 if (copy > 0) {
106 if (copy > len)
107 copy = len;
108 cookie = dma_skb_copy_datagram_iovec(chan, frag_iter,
109 offset - start,
110 to, copy,
111 pinned_list);
112 if (cookie < 0)
113 goto fault;
114 len -= copy;
115 if (len == 0)
116 goto end;
117 offset += copy;
Chris Leechde5506e2006-05-23 17:50:37 -0700118 }
David S. Miller285e4282009-06-09 00:19:10 -0700119 start = end;
Chris Leechde5506e2006-05-23 17:50:37 -0700120 }
121
122end:
123 if (!len) {
124 skb->dma_cookie = cookie;
125 return cookie;
126 }
127
128fault:
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900129 return -EFAULT;
Chris Leechde5506e2006-05-23 17:50:37 -0700130}