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Message-Id: <E1XmjUc-0005Dm-M3@gondolin.me.apana.org.au>
Date: Fri, 07 Nov 2014 21:22:22 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: David Miller <davem@...emloft.net>, viro@...IV.linux.org.uk,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
bcrl@...ck.org, YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>
Subject: [PATCH 1/4] inet: Add skb_copy_datagram_iter
This patch adds skb_copy_datagram_iter, which is identical to
skb_copy_datagram_iovec except that it operates on iov_iter
instead of iovec.
Eventually all users of skb_copy_datagram_iovec should switch
over to iov_iter and then we can remove skb_copy_datagram_iovec.
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
---
include/linux/skbuff.h | 3 +
net/core/datagram.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 90 insertions(+)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 53f4f6c..933cfce 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -150,6 +150,7 @@
struct net_device;
struct scatterlist;
struct pipe_inode_info;
+struct iov_iter;
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
struct nf_conntrack {
@@ -2653,6 +2654,8 @@ int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *frm,
int skb_copy_datagram_const_iovec(const struct sk_buff *from, int offset,
const struct iovec *to, int to_offset,
int size);
+int skb_copy_datagram_iter(const struct sk_buff *from, int offset,
+ struct iov_iter *to, int size);
void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb);
int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);
diff --git a/net/core/datagram.c b/net/core/datagram.c
index fdbc9a8..84d90d0 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -49,6 +49,7 @@
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
+#include <linux/uio.h>
#include <net/protocol.h>
#include <linux/skbuff.h>
@@ -482,6 +483,92 @@ fault:
EXPORT_SYMBOL(skb_copy_datagram_const_iovec);
/**
+ * skb_copy_datagram_iter - Copy a datagram to an iovec iterator.
+ * @skb: buffer to copy
+ * @offset: offset in the buffer to start copying from
+ * @to: iovec iterator to copy to
+ * @len: amount of data to copy from buffer to iovec
+ */
+int skb_copy_datagram_iter(const struct sk_buff *skb, int offset,
+ struct iov_iter *to, int len)
+{
+ int start = skb_headlen(skb);
+ int i, copy = start - offset;
+ struct sk_buff *frag_iter;
+
+ trace_skb_copy_datagram_iovec(skb, len);
+
+ /* Copy header. */
+ if (copy > 0) {
+ if (copy > len)
+ copy = len;
+ if (copy_to_iter(skb->data + offset, copy, to) != copy)
+ goto short_copy;
+ 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;
+ const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+ WARN_ON(start > offset + len);
+
+ end = start + skb_frag_size(frag);
+ if ((copy = end - offset) > 0) {
+ if (copy > len)
+ copy = len;
+ if (copy_page_to_iter(skb_frag_page(frag),
+ frag->page_offset + offset -
+ start, copy, to) != copy)
+ goto short_copy;
+ if (!(len -= copy))
+ return 0;
+ offset += copy;
+ }
+ start = end;
+ }
+
+ skb_walk_frags(skb, frag_iter) {
+ int end;
+
+ WARN_ON(start > offset + len);
+
+ end = start + frag_iter->len;
+ if ((copy = end - offset) > 0) {
+ if (copy > len)
+ copy = len;
+ if (skb_copy_datagram_iter(frag_iter, offset - start,
+ to, copy))
+ goto fault;
+ if ((len -= copy) == 0)
+ return 0;
+ offset += copy;
+ }
+ start = end;
+ }
+ if (!len)
+ return 0;
+
+ /* This is not really a user copy fault, but rather someone
+ * gave us a bogus length on the skb. We should probably
+ * print a warning here as it may indicate a kernel bug.
+ */
+
+fault:
+ return -EFAULT;
+
+short_copy:
+ if (iov_iter_count(to))
+ goto fault;
+
+ return 0;
+}
+EXPORT_SYMBOL(skb_copy_datagram_iter);
+
+/**
* skb_copy_datagram_from_iovec - Copy a datagram from an iovec.
* @skb: buffer to copy
* @offset: offset in the buffer to start copying to
--
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