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1 /* skb_dma_map.c: DMA mapping helpers for socket buffers.
2  *
3  * Copyright (C) David S. Miller <davem@davemloft.net>
4  */
5 
6 #include <linux/kernel.h>
7 #include <linux/module.h>
8 #include <linux/dma-mapping.h>
9 #include <linux/skbuff.h>
10 
skb_dma_map(struct device * dev,struct sk_buff * skb,enum dma_data_direction dir)11 int skb_dma_map(struct device *dev, struct sk_buff *skb,
12 		enum dma_data_direction dir)
13 {
14 	struct skb_shared_info *sp = skb_shinfo(skb);
15 	dma_addr_t map;
16 	int i;
17 
18 	map = dma_map_single(dev, skb->data,
19 			     skb_headlen(skb), dir);
20 	if (dma_mapping_error(dev, map))
21 		goto out_err;
22 
23 	sp->dma_maps[0] = map;
24 	for (i = 0; i < sp->nr_frags; i++) {
25 		skb_frag_t *fp = &sp->frags[i];
26 
27 		map = dma_map_page(dev, fp->page, fp->page_offset,
28 				   fp->size, dir);
29 		if (dma_mapping_error(dev, map))
30 			goto unwind;
31 		sp->dma_maps[i + 1] = map;
32 	}
33 	sp->num_dma_maps = i + 1;
34 
35 	return 0;
36 
37 unwind:
38 	while (--i >= 0) {
39 		skb_frag_t *fp = &sp->frags[i];
40 
41 		dma_unmap_page(dev, sp->dma_maps[i + 1],
42 			       fp->size, dir);
43 	}
44 	dma_unmap_single(dev, sp->dma_maps[0],
45 			 skb_headlen(skb), dir);
46 out_err:
47 	return -ENOMEM;
48 }
49 EXPORT_SYMBOL(skb_dma_map);
50 
skb_dma_unmap(struct device * dev,struct sk_buff * skb,enum dma_data_direction dir)51 void skb_dma_unmap(struct device *dev, struct sk_buff *skb,
52 		   enum dma_data_direction dir)
53 {
54 	struct skb_shared_info *sp = skb_shinfo(skb);
55 	int i;
56 
57 	dma_unmap_single(dev, sp->dma_maps[0],
58 			 skb_headlen(skb), dir);
59 	for (i = 0; i < sp->nr_frags; i++) {
60 		skb_frag_t *fp = &sp->frags[i];
61 
62 		dma_unmap_page(dev, sp->dma_maps[i + 1],
63 			       fp->size, dir);
64 	}
65 }
66 EXPORT_SYMBOL(skb_dma_unmap);
67