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Message-Id: <200808121624.56948.rusty@rustcorp.com.au>
Date: Tue, 12 Aug 2008 16:24:56 +1000
From: Rusty Russell <rusty@...tcorp.com.au>
To: netdev@...r.kernel.org
Cc: Max Krasnyansky <maxk@...lcomm.com>,
Herbert Xu <herbert@...dor.apana.org.au>
Subject: [PATCH 1/2] net: skb_copy_datagram_from_iovec()
There's an skb_copy_datagram_iovec() to copy out of a paged skb, but
nothing the other way around (because we don't do that).
We want to allocate big skbs in tun.c, so let's add the function.
It's a carbon copy of skb_copy_datagram_iovec() with enough changes to
be annoying.
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
include/linux/skbuff.h | 4 ++
net/core/datagram.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 91 insertions(+)
diff -r fcbf6d08c910 include/linux/skbuff.h
--- a/include/linux/skbuff.h Wed Aug 06 11:30:36 2008 +1000
+++ b/include/linux/skbuff.h Wed Aug 06 16:13:41 2008 +1000
@@ -1452,6 +1452,10 @@ extern int skb_copy_and_csum_data
extern int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
int hlen,
struct iovec *iov);
+extern int skb_copy_datagram_from_iovec(struct sk_buff *skb,
+ int offset,
+ struct iovec *from,
+ int len);
extern void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
extern int skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
unsigned int flags);
diff -r fcbf6d08c910 net/core/datagram.c
--- a/net/core/datagram.c Wed Aug 06 11:30:36 2008 +1000
+++ b/net/core/datagram.c Wed Aug 06 16:13:41 2008 +1000
@@ -339,6 +339,93 @@ fault:
return -EFAULT;
}
+/**
+ * skb_copy_datagram_from_iovec - Copy a datagram from an iovec.
+ * @skb: buffer to copy
+ * @offset: offset in the buffer to start copying to
+ * @from: io vector to copy to
+ * @len: amount of data to copy to buffer from iovec
+ *
+ * Returns 0 or -EFAULT.
+ * Note: the iovec is modified during the copy.
+ */
+int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
+ struct iovec *from, int len)
+{
+ int start = skb_headlen(skb);
+ int i, copy = start - offset;
+
+ /* Copy header. */
+ if (copy > 0) {
+ if (copy > len)
+ copy = len;
+ if (memcpy_fromiovec(skb->data + offset, from, copy))
+ goto fault;
+ if ((len -= copy) == 0)
+ return 0;
+ offset += copy;
+ }
+
+ /* Copy paged appendix. Hmm... why does this look so complicated? */
+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+ int end;
+
+ WARN_ON(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 (copy > len)
+ copy = len;
+ vaddr = kmap(page);
+ err = memcpy_fromiovec(vaddr + frag->page_offset +
+ offset - start, from, copy);
+ kunmap(page);
+ if (err)
+ goto fault;
+
+ if (!(len -= copy))
+ return 0;
+ offset += copy;
+ }
+ start = end;
+ }
+
+ if (skb_shinfo(skb)->frag_list) {
+ struct sk_buff *list = skb_shinfo(skb)->frag_list;
+
+ for (; list; list = list->next) {
+ int end;
+
+ WARN_ON(start > offset + len);
+
+ end = start + list->len;
+ if ((copy = end - offset) > 0) {
+ if (copy > len)
+ copy = len;
+ if (skb_copy_datagram_from_iovec(list,
+ offset - start,
+ from, copy))
+ goto fault;
+ if ((len -= copy) == 0)
+ return 0;
+ offset += copy;
+ }
+ start = end;
+ }
+ }
+ if (!len)
+ return 0;
+
+fault:
+ return -EFAULT;
+}
+EXPORT_SYMBOL(skb_copy_datagram_from_iovec);
+
static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
u8 __user *to, int len,
__wsum *csump)
--
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