Commit c3bdeb5c authored by Jason Wang's avatar Jason Wang Committed by David S. Miller
Browse files

net: move zerocopy_sg_from_iovec() to net/core/datagram.c 



To let it be reused and reduce code duplication. Also document this function.

Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b4bf0777

drivers/net/macvtap.c

+0 −80
Original line number Diff line number Diff line
@@ -536,86 +536,6 @@ static inline struct sk_buff *macvtap_alloc_skb(struct sock *sk, size_t prepad, 
	return skb;

}



/* set skb frags from iovec, this can move to core network code for reuse */

static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,

				  int offset, size_t count)

{

	int len = iov_length(from, count) - offset;

	int copy = skb_headlen(skb);

	int size, offset1 = 0;

	int i = 0;



	/* Skip over from offset */

	while (count && (offset >= from->iov_len)) {

		offset -= from->iov_len;

		++from;

		--count;

	}



	/* copy up to skb headlen */

	while (count && (copy > 0)) {

		size = min_t(unsigned int, copy, from->iov_len - offset);

		if (copy_from_user(skb->data + offset1, from->iov_base + offset,

				   size))

			return -EFAULT;

		if (copy > size) {

			++from;

			--count;

			offset = 0;

		} else

			offset += size;

		copy -= size;

		offset1 += size;

	}



	if (len == offset1)

		return 0;



	while (count--) {

		struct page *page[MAX_SKB_FRAGS];

		int num_pages;

		unsigned long base;

		unsigned long truesize;



		len = from->iov_len - offset;

		if (!len) {

			offset = 0;

			++from;

			continue;

		}

		base = (unsigned long)from->iov_base + offset;

		size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;

		if (i + size > MAX_SKB_FRAGS)

			return -EMSGSIZE;

		num_pages = get_user_pages_fast(base, size, 0, &page[i]);

		if (num_pages != size) {

			int j;



			for (j = 0; j < num_pages; j++)

				put_page(page[i + j]);

			return -EFAULT;

		}

		truesize = size * PAGE_SIZE;

		skb->data_len += len;

		skb->len += len;

		skb->truesize += truesize;

		atomic_add(truesize, &skb->sk->sk_wmem_alloc);

		while (len) {

			int off = base & ~PAGE_MASK;

			int size = min_t(int, len, PAGE_SIZE - off);

			__skb_fill_page_desc(skb, i, page[i], off, size);

			skb_shinfo(skb)->nr_frags++;

			/* increase sk_wmem_alloc */

			base += size;

			len -= size;

			i++;

		}

		offset = 0;

		++from;

	}

	return 0;

}



/*

 * macvtap_skb_from_vnet_hdr and macvtap_skb_to_vnet_hdr should

 * be shared with the tun/tap driver.

drivers/net/tun.c

+0 −80
Original line number Diff line number Diff line
@@ -961,86 +961,6 @@ static struct sk_buff *tun_alloc_skb(struct tun_file *tfile, 
	return skb;

}



/* set skb frags from iovec, this can move to core network code for reuse */

static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,

				  int offset, size_t count)

{

	int len = iov_length(from, count) - offset;

	int copy = skb_headlen(skb);

	int size, offset1 = 0;

	int i = 0;



	/* Skip over from offset */

	while (count && (offset >= from->iov_len)) {

		offset -= from->iov_len;

		++from;

		--count;

	}



	/* copy up to skb headlen */

	while (count && (copy > 0)) {

		size = min_t(unsigned int, copy, from->iov_len - offset);

		if (copy_from_user(skb->data + offset1, from->iov_base + offset,

				   size))

			return -EFAULT;

		if (copy > size) {

			++from;

			--count;

			offset = 0;

		} else

			offset += size;

		copy -= size;

		offset1 += size;

	}



	if (len == offset1)

		return 0;



	while (count--) {

		struct page *page[MAX_SKB_FRAGS];

		int num_pages;

		unsigned long base;

		unsigned long truesize;



		len = from->iov_len - offset;

		if (!len) {

			offset = 0;

			++from;

			continue;

		}

		base = (unsigned long)from->iov_base + offset;

		size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;

		if (i + size > MAX_SKB_FRAGS)

			return -EMSGSIZE;

		num_pages = get_user_pages_fast(base, size, 0, &page[i]);

		if (num_pages != size) {

			int j;



			for (j = 0; j < num_pages; j++)

				put_page(page[i + j]);

			return -EFAULT;

		}

		truesize = size * PAGE_SIZE;

		skb->data_len += len;

		skb->len += len;

		skb->truesize += truesize;

		atomic_add(truesize, &skb->sk->sk_wmem_alloc);

		while (len) {

			int off = base & ~PAGE_MASK;

			int size = min_t(int, len, PAGE_SIZE - off);

			__skb_fill_page_desc(skb, i, page[i], off, size);

			skb_shinfo(skb)->nr_frags++;

			/* increase sk_wmem_alloc */

			base += size;

			len -= size;

			i++;

		}

		offset = 0;

		++from;

	}

	return 0;

}



/* Get packet from user space buffer */

static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,

			    void *msg_control, const struct iovec *iv,

include/linux/skbuff.h

+4 −0
Original line number Diff line number Diff line
@@ -2359,6 +2359,10 @@ extern int skb_copy_datagram_from_iovec(struct sk_buff *skb, 
						    const struct iovec *from,

						    int from_offset,

						    int len);

extern int	       zerocopy_sg_from_iovec(struct sk_buff *skb,

					      const struct iovec *frm,

					      int offset,

					      size_t count);

extern int	       skb_copy_datagram_const_iovec(const struct sk_buff *from,

						     int offset,

						     const struct iovec *to,

net/core/datagram.c

+93 −0
Original line number Diff line number Diff line
@@ -573,6 +573,99 @@ int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset, 
}

EXPORT_SYMBOL(skb_copy_datagram_from_iovec);



/**

 *	zerocopy_sg_from_iovec - Build a zerocopy datagram from an iovec

 *	@skb: buffer to copy

 *	@from: io vector to copy to

 *	@offset: offset in the io vector to start copying from

 *	@count: amount of vectors to copy to buffer from

 *

 *	The function will first copy up to headlen, and then pin the userspace

 *	pages and build frags through them.

 *

 *	Returns 0, -EFAULT or -EMSGSIZE.

 *	Note: the iovec is not modified during the copy

 */

int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,

				  int offset, size_t count)

{

	int len = iov_length(from, count) - offset;

	int copy = skb_headlen(skb);

	int size, offset1 = 0;

	int i = 0;



	/* Skip over from offset */

	while (count && (offset >= from->iov_len)) {

		offset -= from->iov_len;

		++from;

		--count;

	}



	/* copy up to skb headlen */

	while (count && (copy > 0)) {

		size = min_t(unsigned int, copy, from->iov_len - offset);

		if (copy_from_user(skb->data + offset1, from->iov_base + offset,

				   size))

			return -EFAULT;

		if (copy > size) {

			++from;

			--count;

			offset = 0;

		} else

			offset += size;

		copy -= size;

		offset1 += size;

	}



	if (len == offset1)

		return 0;



	while (count--) {

		struct page *page[MAX_SKB_FRAGS];

		int num_pages;

		unsigned long base;

		unsigned long truesize;



		len = from->iov_len - offset;

		if (!len) {

			offset = 0;

			++from;

			continue;

		}

		base = (unsigned long)from->iov_base + offset;

		size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;

		if (i + size > MAX_SKB_FRAGS)

			return -EMSGSIZE;

		num_pages = get_user_pages_fast(base, size, 0, &page[i]);

		if (num_pages != size) {

			int j;



			for (j = 0; j < num_pages; j++)

				put_page(page[i + j]);

			return -EFAULT;

		}

		truesize = size * PAGE_SIZE;

		skb->data_len += len;

		skb->len += len;

		skb->truesize += truesize;

		atomic_add(truesize, &skb->sk->sk_wmem_alloc);

		while (len) {

			int off = base & ~PAGE_MASK;

			int size = min_t(int, len, PAGE_SIZE - off);

			__skb_fill_page_desc(skb, i, page[i], off, size);

			skb_shinfo(skb)->nr_frags++;

			/* increase sk_wmem_alloc */

			base += size;

			len -= size;

			i++;

		}

		offset = 0;

		++from;

	}

	return 0;

}

EXPORT_SYMBOL(zerocopy_sg_from_iovec);



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

				      u8 __user *to, int len,

				      __wsum *csump)