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de5506e1 CL |
1 | /* |
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> | |
30 | #include <linux/rtnetlink.h> /* for BUG_TRAP */ | |
31 | #include <net/tcp.h> | |
64d2f085 | 32 | #include <net/netdma.h> |
de5506e1 | 33 | |
95937825 CL |
34 | #define NET_DMA_DEFAULT_COPYBREAK 4096 |
35 | ||
36 | int sysctl_tcp_dma_copybreak = NET_DMA_DEFAULT_COPYBREAK; | |
37 | ||
de5506e1 CL |
38 | /** |
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 | */ | |
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) | |
51 | { | |
1a028e50 DM |
52 | int start = skb_headlen(skb); |
53 | int i, copy = start - offset; | |
de5506e1 CL |
54 | dma_cookie_t cookie = 0; |
55 | ||
56 | /* Copy header. */ | |
57 | if (copy > 0) { | |
58 | if (copy > len) | |
59 | copy = len; | |
60 | cookie = dma_memcpy_to_iovec(chan, to, pinned_list, | |
4ec93edb | 61 | skb->data + offset, copy); |
de5506e1 CL |
62 | if (cookie < 0) |
63 | goto fault; | |
64 | len -= copy; | |
65 | if (len == 0) | |
66 | goto end; | |
67 | offset += copy; | |
68 | } | |
69 | ||
70 | /* Copy paged appendix. Hmm... why does this look so complicated? */ | |
71 | for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { | |
1a028e50 | 72 | int end; |
de5506e1 | 73 | |
1a028e50 DM |
74 | BUG_TRAP(start <= offset + len); |
75 | ||
76 | end = start + skb_shinfo(skb)->frags[i].size; | |
de5506e1 | 77 | copy = end - offset; |
7557af25 | 78 | if (copy > 0) { |
de5506e1 CL |
79 | skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; |
80 | struct page *page = frag->page; | |
81 | ||
82 | if (copy > len) | |
83 | copy = len; | |
84 | ||
1a028e50 DM |
85 | cookie = dma_memcpy_pg_to_iovec(chan, to, pinned_list, page, |
86 | frag->page_offset + offset - start, copy); | |
de5506e1 CL |
87 | if (cookie < 0) |
88 | goto fault; | |
89 | len -= copy; | |
90 | if (len == 0) | |
91 | goto end; | |
92 | offset += copy; | |
93 | } | |
1a028e50 | 94 | start = end; |
de5506e1 CL |
95 | } |
96 | ||
97 | if (skb_shinfo(skb)->frag_list) { | |
98 | struct sk_buff *list = skb_shinfo(skb)->frag_list; | |
99 | ||
100 | for (; list; list = list->next) { | |
1a028e50 DM |
101 | int end; |
102 | ||
103 | BUG_TRAP(start <= offset + len); | |
de5506e1 | 104 | |
1a028e50 | 105 | end = start + list->len; |
de5506e1 CL |
106 | copy = end - offset; |
107 | if (copy > 0) { | |
108 | if (copy > len) | |
109 | copy = len; | |
110 | cookie = dma_skb_copy_datagram_iovec(chan, list, | |
1a028e50 DM |
111 | offset - start, to, copy, |
112 | pinned_list); | |
de5506e1 CL |
113 | if (cookie < 0) |
114 | goto fault; | |
115 | len -= copy; | |
116 | if (len == 0) | |
117 | goto end; | |
118 | offset += copy; | |
119 | } | |
1a028e50 | 120 | start = end; |
de5506e1 CL |
121 | } |
122 | } | |
123 | ||
124 | end: | |
125 | if (!len) { | |
126 | skb->dma_cookie = cookie; | |
127 | return cookie; | |
128 | } | |
129 | ||
130 | fault: | |
4ec93edb | 131 | return -EFAULT; |
de5506e1 | 132 | } |