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Commit 20bf50de authored by Tom Herbert's avatar Tom Herbert Committed by David S. Miller
Browse files

skbuff: Function to send an skbuf on a socket 



Add skb_send_sock to send an skbuff on a socket within the kernel.
Arguments include an offset so that an skbuf might be sent in mulitple
calls (e.g. send buffer limit is hit).

Signed-off-by: default avatarTom Herbert <tom@quantonium.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 306b13eb

include/linux/skbuff.h

+3 −0
Original line number Diff line number Diff line
@@ -3113,6 +3113,9 @@ __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to, 
int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,

		    struct pipe_inode_info *pipe, unsigned int len,

		    unsigned int flags);

int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,

			 int len);

int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len);

void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);

unsigned int skb_zerocopy_headlen(const struct sk_buff *from);

int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,

net/core/skbuff.c

+101 −0
Original line number Diff line number Diff line
@@ -1982,6 +1982,107 @@ int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset, 
}

EXPORT_SYMBOL_GPL(skb_splice_bits);



/* Send skb data on a socket. Socket must be locked. */

int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,

			 int len)

{

	unsigned int orig_len = len;

	struct sk_buff *head = skb;

	unsigned short fragidx;

	int slen, ret;



do_frag_list:



	/* Deal with head data */

	while (offset < skb_headlen(skb) && len) {

		struct kvec kv;

		struct msghdr msg;



		slen = min_t(int, len, skb_headlen(skb) - offset);

		kv.iov_base = skb->data + offset;

		kv.iov_len = len;

		memset(&msg, 0, sizeof(msg));



		ret = kernel_sendmsg_locked(sk, &msg, &kv, 1, slen);

		if (ret <= 0)

			goto error;



		offset += ret;

		len -= ret;

	}



	/* All the data was skb head? */

	if (!len)

		goto out;



	/* Make offset relative to start of frags */

	offset -= skb_headlen(skb);



	/* Find where we are in frag list */

	for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {

		skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];



		if (offset < frag->size)

			break;



		offset -= frag->size;

	}



	for (; len && fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {

		skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];



		slen = min_t(size_t, len, frag->size - offset);



		while (slen) {

			ret = kernel_sendpage_locked(sk, frag->page.p,

						     frag->page_offset + offset,

						     slen, MSG_DONTWAIT);

			if (ret <= 0)

				goto error;



			len -= ret;

			offset += ret;

			slen -= ret;

		}



		offset = 0;

	}



	if (len) {

		/* Process any frag lists */



		if (skb == head) {

			if (skb_has_frag_list(skb)) {

				skb = skb_shinfo(skb)->frag_list;

				goto do_frag_list;

			}

		} else if (skb->next) {

			skb = skb->next;

			goto do_frag_list;

		}

	}



out:

	return orig_len - len;



error:

	return orig_len == len ? ret : orig_len - len;

}

EXPORT_SYMBOL_GPL(skb_send_sock_locked);



/* Send skb data on a socket. */

int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)

{

	int ret = 0;



	lock_sock(sk);

	ret = skb_send_sock_locked(sk, skb, offset, len);

	release_sock(sk);



	return ret;

}

EXPORT_SYMBOL_GPL(skb_send_sock);



/**

 *	skb_store_bits - store bits from kernel buffer to skb

 *	@skb: destination buffer