diff --git a/net/core/datagram.c b/net/core/datagram.c index da9bf71421a7..81987df536eb 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -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; }