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#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#if !defined(HAVE_SKB_WARN_LRO) && defined(NETIF_F_LRO)
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
void __skb_warn_lro_forwarding(const struct sk_buff *skb)
{
if (net_ratelimit())
pr_warn("%s: received packets cannot be forwarded while LRO is enabled\n",
skb->dev->name);
}
#endif
#if LINUX_VERSION_CODE < KERNEL_VERSION(3,14,0)
static inline bool head_frag(const struct sk_buff *skb)
{
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,5,0)
return skb->head_frag;
#else
return false;
#endif
}
/**
* skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
* @from: source buffer
*
* Calculates the amount of linear headroom needed in the 'to' skb passed
* into skb_zerocopy().
*/
unsigned int
skb_zerocopy_headlen(const struct sk_buff *from)
{
unsigned int hlen = 0;
if (!head_frag(from) ||
skb_headlen(from) < L1_CACHE_BYTES ||
skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
hlen = skb_headlen(from);
if (skb_has_frag_list(from))
hlen = from->len;
return hlen;
}
/**
* skb_zerocopy - Zero copy skb to skb
* @to: destination buffer
* @source: source buffer
* @len: number of bytes to copy from source buffer
* @hlen: size of linear headroom in destination buffer
*
* Copies up to `len` bytes from `from` to `to` by creating references
* to the frags in the source buffer.
*
* The `hlen` as calculated by skb_zerocopy_headlen() specifies the
* headroom in the `to` buffer.
*
* Return value:
* 0: everything is OK
* -ENOMEM: couldn't orphan frags of @from due to lack of memory
* -EFAULT: skb_copy_bits() found some problem with skb geometry
*/
int
skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
{
int i, j = 0;
int plen = 0; /* length of skb->head fragment */
int ret;
struct page *page;
unsigned int offset;
BUG_ON(!head_frag(from) && !hlen);
/* dont bother with small payloads */
if (len <= skb_tailroom(to))
return skb_copy_bits(from, 0, skb_put(to, len), len);
if (hlen) {
ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
if (unlikely(ret))
return ret;
len -= hlen;
} else {
plen = min_t(int, skb_headlen(from), len);
if (plen) {
page = virt_to_head_page(from->head);
offset = from->data - (unsigned char *)page_address(page);
__skb_fill_page_desc(to, 0, page, offset, plen);
get_page(page);
j = 1;
len -= plen;
}
}
to->truesize += len + plen;
to->len += len + plen;
to->data_len += len + plen;
if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
skb_tx_error(from);
return -ENOMEM;
}
for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
if (!len)
break;
skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
skb_shinfo(to)->frags[j].size = min_t(int, skb_shinfo(to)->frags[j].size, len);
len -= skb_shinfo(to)->frags[j].size;
skb_frag_ref(to, j);
j++;
}
skb_shinfo(to)->nr_frags = j;
return 0;
}
#endif
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