root/net/core/skb_dma_map.c

DEFINITIONS

1. skb_dma_map
2. skb_dma_unmap

/* skb_dma_map.c: DMA mapping helpers for socket buffers.
 *
 * Copyright (C) David S. Miller <davem@davemloft.net>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/dma-mapping.h>
#include <linux/skbuff.h>

int skb_dma_map(struct device *dev, struct sk_buff *skb,
                enum dma_data_direction dir)
{
        struct skb_shared_info *sp = skb_shinfo(skb);
        dma_addr_t map;
        int i;

        map = dma_map_single(dev, skb->data,
                             skb_headlen(skb), dir);
        if (dma_mapping_error(dev, map))
                goto out_err;

        sp->dma_maps[0] = map;
        for (i = 0; i < sp->nr_frags; i++) {
                skb_frag_t *fp = &sp->frags[i];

                map = dma_map_page(dev, fp->page, fp->page_offset,
                                   fp->size, dir);
                if (dma_mapping_error(dev, map))
                        goto unwind;
                sp->dma_maps[i + 1] = map;
        }
        sp->num_dma_maps = i + 1;

        return 0;

unwind:
        while (--i >= 0) {
                skb_frag_t *fp = &sp->frags[i];

                dma_unmap_page(dev, sp->dma_maps[i + 1],
                               fp->size, dir);
        }
        dma_unmap_single(dev, sp->dma_maps[0],
                         skb_headlen(skb), dir);
out_err:
        return -ENOMEM;
}
EXPORT_SYMBOL(skb_dma_map);

void skb_dma_unmap(struct device *dev, struct sk_buff *skb,
                   enum dma_data_direction dir)
{
        struct skb_shared_info *sp = skb_shinfo(skb);
        int i;

        dma_unmap_single(dev, sp->dma_maps[0],
                         skb_headlen(skb), dir);
        for (i = 0; i < sp->nr_frags; i++) {
                skb_frag_t *fp = &sp->frags[i];

                dma_unmap_page(dev, sp->dma_maps[i + 1],
                               fp->size, dir);
        }
}
EXPORT_SYMBOL(skb_dma_unmap);