This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / net / core / user_dma.c

diff --git a/net/core/user_dma.c b/net/core/user_dma.c
new file mode 100644 (file)
index 0000000..248a6b6
--- /dev/null
+++ b/net/core/user_dma.c
@@ -0,0 +1,132 @@
+/*
+ * Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
+ * Portions based on net/core/datagram.c and copyrighted by their authors.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ *
+ * The full GNU General Public License is included in this distribution in the
+ * file called COPYING.
+ */
+
+/*
+ * This code allows the net stack to make use of a DMA engine for
+ * skb to iovec copies.
+ */
+
+#include <linux/dmaengine.h>
+#include <linux/socket.h>
+#include <linux/rtnetlink.h> /* for BUG_TRAP */
+#include <net/tcp.h>
+#include <net/netdma.h>
+
+#define NET_DMA_DEFAULT_COPYBREAK 4096
+
+int sysctl_tcp_dma_copybreak = NET_DMA_DEFAULT_COPYBREAK;
+
+/**
+ *     dma_skb_copy_datagram_iovec - Copy a datagram to an iovec.
+ *     @skb - buffer to copy
+ *     @offset - offset in the buffer to start copying from
+ *     @iovec - io vector to copy to
+ *     @len - amount of data to copy from buffer to iovec
+ *     @pinned_list - locked iovec buffer data
+ *
+ *     Note: the iovec is modified during the copy.
+ */
+int dma_skb_copy_datagram_iovec(struct dma_chan *chan,
+                       struct sk_buff *skb, int offset, struct iovec *to,
+                       size_t len, struct dma_pinned_list *pinned_list)
+{
+       int start = skb_headlen(skb);
+       int i, copy = start - offset;
+       dma_cookie_t cookie = 0;
+
+       /* Copy header. */
+       if (copy > 0) {
+               if (copy > len)
+                       copy = len;
+               cookie = dma_memcpy_to_iovec(chan, to, pinned_list,
+                                           skb->data + offset, copy);
+               if (cookie < 0)
+                       goto fault;
+               len -= copy;
+               if (len == 0)
+                       goto end;
+               offset += copy;
+       }
+
+       /* Copy paged appendix. Hmm... why does this look so complicated? */
+       for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+               int end;
+
+               BUG_TRAP(start <= offset + len);
+
+               end = start + skb_shinfo(skb)->frags[i].size;
+               copy = end - offset;
+               if ((copy = end - offset) > 0) {
+                       skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+                       struct page *page = frag->page;
+
+                       if (copy > len)
+                               copy = len;
+
+                       cookie = dma_memcpy_pg_to_iovec(chan, to, pinned_list, page,
+                                       frag->page_offset + offset - start, copy);
+                       if (cookie < 0)
+                               goto fault;
+                       len -= copy;
+                       if (len == 0)
+                               goto end;
+                       offset += copy;
+               }
+               start = end;
+       }
+
+       if (skb_shinfo(skb)->frag_list) {
+               struct sk_buff *list = skb_shinfo(skb)->frag_list;
+
+               for (; list; list = list->next) {
+                       int end;
+
+                       BUG_TRAP(start <= offset + len);
+
+                       end = start + list->len;
+                       copy = end - offset;
+                       if (copy > 0) {
+                               if (copy > len)
+                                       copy = len;
+                               cookie = dma_skb_copy_datagram_iovec(chan, list,
+                                               offset - start, to, copy,
+                                               pinned_list);
+                               if (cookie < 0)
+                                       goto fault;
+                               len -= copy;
+                               if (len == 0)
+                                       goto end;
+                               offset += copy;
+                       }
+                       start = end;
+               }
+       }
+
+end:
+       if (!len) {
+               skb->dma_cookie = cookie;
+               return cookie;
+       }
+
+fault:
+       return -EFAULT;
+}