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[NET]: Use non-recursive algorithm in skb_copy_datagram_iovec() 

Use iteration instead of recursion.  Fraglists within fraglists
should never occur, so we BUG check this.

Signed-off-by: Daniel Phillips <phillips@istop.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Phillips 2005-09-27 15:22:35 -07:00 committed by David S. Miller
parent 95001ee925
commit bc8dfcb939
1 changed files with 26 additions and 55 deletions
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81
net/core/datagram.c
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@ -211,74 +211,45 @@ void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
int skb_copy_datagram_iovec(const struct sk_buff *skb, int offset,
struct iovec *to, int len)
{
int start = skb_headlen(skb);
int i, copy = start - offset;
int i, err, fraglen, end = 0;
struct sk_buff *next = skb_shinfo(skb)->frag_list;
next_skb:
fraglen = skb_headlen(skb);
i = -1;
/* Copy header. */
if (copy > 0) {
if (copy > len)
copy = len;
if (memcpy_toiovec(to, skb->data + offset, copy))
goto fault;
if ((len -= copy) == 0)
return 0;
offset += copy;
}
while (1) {
int start = end;
/* 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;
if ((copy = end - offset) > 0) {
int err;
u8 *vaddr;
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
struct page *page = frag->page;
if ((end += fraglen) > offset) {
int copy = end - offset, o = offset - start;
if (copy > len)
copy = len;
vaddr = kmap(page);
err = memcpy_toiovec(to, vaddr + frag->page_offset +
offset - start, copy);
kunmap(page);
if (i == -1)
err = memcpy_toiovec(to, skb->data + o, copy);
else {
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
struct page *page = frag->page;
void *p = kmap(page) + frag->page_offset + o;
err = memcpy_toiovec(to, p, copy);
kunmap(page);
}
if (err)
goto fault;
if (!(len -= copy))
return 0;
offset += copy;
}
start = end;
if (++i >= skb_shinfo(skb)->nr_frags)
break;
fraglen = skb_shinfo(skb)->frags[i].size;
}
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;
if ((copy = end - offset) > 0) {
if (copy > len)
copy = len;
if (skb_copy_datagram_iovec(list,
offset - start,
to, copy))
goto fault;
if ((len -= copy) == 0)
return 0;
offset += copy;
}
start = end;
}
if (next) {
skb = next;
BUG_ON(skb_shinfo(skb)->frag_list);
next = skb->next;
goto next_skb;
}
if (!len)
return 0;
fault:
return -EFAULT;
}