/* * 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/export.h> #include <net/tcp.h> #include <net/netdma.h> #define NET_DMA_DEFAULT_COPYBREAK 4096 int sysctl_tcp_dma_copybreak = NET_DMA_DEFAULT_COPYBREAK; EXPORT_SYMBOL(sysctl_tcp_dma_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; struct sk_buff *frag_iter; 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; const skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; WARN_ON(start > offset + len); end = start + skb_frag_size(frag); copy = end - offset; if (copy > 0) { struct page *page = skb_frag_page(frag); 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; } skb_walk_frags(skb, frag_iter) { int end; WARN_ON(start > offset + len); end = start + frag_iter->len; copy = end - offset; if (copy > 0) { if (copy > len) copy = len; cookie = dma_skb_copy_datagram_iovec(chan, frag_iter, 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; }