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Commit 950fcaec authored by Sagi Grimberg's avatar Sagi Grimberg Committed by Christoph Hellwig
Browse files

datagram: consolidate datagram copy to iter helpers 



skb_copy_datagram_iter and skb_copy_and_csum_datagram are essentialy
the same but with a couple of differences: The first is the copy
operation used which either a simple copy or a csum_and_copy, and the
second are the behavior on the "short copy" path where simply copy
needs to return the number of bytes successfully copied while csum_and_copy
needs to fault immediately as the checksum is partial.

Introduce __skb_datagram_iter that additionally accepts:
1. copy operation function pointer
2. private data that goes with the copy operation
3. fault_short flag to indicate the action on short copy

Suggested-by: default avatarDavid S. Miller <davem@davemloft.net>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSagi Grimberg <sagi@lightbitslabs.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent cb002d07

net/core/datagram.c

+42 −94
Original line number Diff line number Diff line
@@ -408,27 +408,20 @@ int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags) 
}

EXPORT_SYMBOL(skb_kill_datagram);



/**

 *	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 __skb_datagram_iter(const struct sk_buff *skb, int offset,

			struct iov_iter *to, int len, bool fault_short,

			size_t (*cb)(const void *, size_t, void *, struct iov_iter *),

			void *data)

{

	int start = skb_headlen(skb);

	int i, copy = start - offset, start_off = offset, n;

	struct sk_buff *frag_iter;



	trace_skb_copy_datagram_iovec(skb, len);



	/* Copy header. */

	if (copy > 0) {

		if (copy > len)

			copy = len;

		n = copy_to_iter(skb->data + offset, copy, to);

		n = cb(skb->data + offset, copy, data, to);

		offset += n;

		if (n != copy)

			goto short_copy;
@@ -450,8 +443,8 @@ int skb_copy_datagram_iter(const struct sk_buff *skb, int offset, 


			if (copy > len)

				copy = len;

			n = copy_to_iter(vaddr + frag->page_offset +

					 offset - start, copy, to);

			n = cb(vaddr + frag->page_offset +

				offset - start, copy, data, to);

			kunmap(page);

			offset += n;

			if (n != copy)
@@ -471,8 +464,8 @@ int skb_copy_datagram_iter(const struct sk_buff *skb, int offset, 
		if ((copy = end - offset) > 0) {

			if (copy > len)

				copy = len;

			if (skb_copy_datagram_iter(frag_iter, offset - start,

						   to, copy))

			if (__skb_datagram_iter(frag_iter, offset - start,

						to, copy, short_copy, cb, data))

				goto fault;

			if ((len -= copy) == 0)

				return 0;
@@ -493,11 +486,32 @@ int skb_copy_datagram_iter(const struct sk_buff *skb, int offset, 
	return -EFAULT;



short_copy:

	if (iov_iter_count(to))

	if (fault_short || iov_iter_count(to))

		goto fault;



	return 0;

}



static size_t simple_copy_to_iter(const void *addr, size_t bytes,

		void *data __always_unused, struct iov_iter *i)

{

	return copy_to_iter(addr, bytes, i);

}



/**

 *	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)

{

	trace_skb_copy_datagram_iovec(skb, len);

	return __skb_datagram_iter(skb, offset, to, len, false,

			simple_copy_to_iter, NULL);

}

EXPORT_SYMBOL(skb_copy_datagram_iter);



/**
@@ -648,87 +662,21 @@ int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from) 
}

EXPORT_SYMBOL(zerocopy_sg_from_iter);



/**

 *	skb_copy_and_csum_datagram_iter - Copy datagram to an iovec iterator

 *          and update a checksum.

 *	@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

 *      @csump: checksum pointer

 */

static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,

				      struct iov_iter *to, int len,

				      __wsum *csump)

{

	int start = skb_headlen(skb);

	int i, copy = start - offset, start_off = offset;

	struct sk_buff *frag_iter;

	int pos = 0;

	int n;



	/* Copy header. */

	if (copy > 0) {

		if (copy > len)

			copy = len;

		n = csum_and_copy_to_iter(skb->data + offset, copy, csump, to);

		offset += n;

		if (n != copy)

			goto fault;

		if ((len -= copy) == 0)

			return 0;

		pos = copy;

	}



	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) {

			__wsum csum2 = 0;

			struct page *page = skb_frag_page(frag);

			u8  *vaddr = kmap(page);



			if (copy > len)

				copy = len;

			n = csum_and_copy_to_iter(vaddr + frag->page_offset +

						  offset - start, copy,

						  &csum2, to);

			kunmap(page);

			offset += n;

			if (n != copy)

				goto fault;

			*csump = csum_block_add(*csump, csum2, pos);

			if (!(len -= copy))

				return 0;

			pos += 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) {

			__wsum csum2 = 0;

			if (copy > len)

				copy = len;

			if (skb_copy_and_csum_datagram(frag_iter,

						       offset - start,

						       to, copy,

						       &csum2))

				goto fault;

			*csump = csum_block_add(*csump, csum2, pos);

			if ((len -= copy) == 0)

				return 0;

			offset += copy;

			pos += copy;

		}

		start = end;

	}

	if (!len)

		return 0;



fault:

	iov_iter_revert(to, offset - start_off);

	return -EFAULT;

	return __skb_datagram_iter(skb, offset, to, len, true,

			csum_and_copy_to_iter, csump);

}



__sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)