new helpers: skb_copy_datagram_from_iter() and zerocopy_sg_from_iter() (3a654f97) · Commits · e / devices / android_kernel_samsung_exynos9810

include/linux/skbuff.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -2659,10 +2659,13 @@ static inline int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, int hlen,
		int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
		const struct iovec *from, int from_offset,
		int len);
		int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
		struct iov_iter *from, int len);
		int zerocopy_sg_from_iovec(struct sk_buff skb, const struct iovec frm,
		int offset, size_t count);
		int skb_copy_datagram_iter(const struct sk_buff *from, int offset,
		struct iov_iter *to, int size);
		int zerocopy_sg_from_iter(struct sk_buff skb, struct iov_iter frm);
		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);

net/core/datagram.c

+116 −0

Original line number	Diff line number	Diff line
		@@ -572,6 +572,78 @@ int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
		}
		EXPORT_SYMBOL(skb_copy_datagram_from_iovec);

		int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
		struct iov_iter *from,
		int len)
		{
		int start = skb_headlen(skb);
		int i, copy = start - offset;
		struct sk_buff *frag_iter;

		/* Copy header. */
		if (copy > 0) {
		if (copy > len)
		copy = len;
		if (copy_from_iter(skb->data + offset, copy, 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;
		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) {
		size_t copied;

		if (copy > len)
		copy = len;
		copied = copy_page_from_iter(skb_frag_page(frag),
		frag->page_offset + offset - start,
		copy, from);
		if (copied != copy)
		goto fault;

		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_from_iter(frag_iter,
		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_iter);

		/**
		* zerocopy_sg_from_iovec - Build a zerocopy datagram from an iovec
		* @skb: buffer to copy
		@@ -643,6 +715,50 @@ int zerocopy_sg_from_iovec(struct sk_buff skb, const struct iovec from,
		}
		EXPORT_SYMBOL(zerocopy_sg_from_iovec);

		int zerocopy_sg_from_iter(struct sk_buff skb, struct iov_iter from)
		{
		int len = iov_iter_count(from);
		int copy = min_t(int, skb_headlen(skb), len);
		int frag = 0;

		/* copy up to skb headlen */
		if (skb_copy_datagram_from_iter(skb, 0, from, copy))
		return -EFAULT;

		while (iov_iter_count(from)) {
		struct page *pages[MAX_SKB_FRAGS];
		size_t start;
		ssize_t copied;
		unsigned long truesize;
		int n = 0;

		if (frag == MAX_SKB_FRAGS)
		return -EMSGSIZE;

		copied = iov_iter_get_pages(from, pages, ~0U,
		MAX_SKB_FRAGS - frag, &start);
		if (copied < 0)
		return -EFAULT;

		iov_iter_advance(from, copied);

		truesize = PAGE_ALIGN(copied + start);
		skb->data_len += copied;
		skb->len += copied;
		skb->truesize += truesize;
		atomic_add(truesize, &skb->sk->sk_wmem_alloc);
		while (copied) {
		int size = min_t(int, copied, PAGE_SIZE - start);
		skb_fill_page_desc(skb, frag++, pages[n], start, size);
		start = 0;
		copied -= size;
		n++;
		}
		}
		return 0;
		}
		EXPORT_SYMBOL(zerocopy_sg_from_iter);

		static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
		u8 __user *to, int len,
		__wsum *csump)