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Commit 57be5bda authored by Al Viro's avatar Al Viro
Browse files

ip: convert tcp_sendmsg() to iov_iter primitives 



patch is actually smaller than it seems to be - most of it is unindenting
the inner loop body in tcp_sendmsg() itself...

the bit in tcp_input.c is going to get reverted very soon - that's what
memcpy_from_msg() will become, but not in this commit; let's keep it
reasonably contained...

There's one potentially subtle change here: in case of short copy from
userland, mainline tcp_send_syn_data() discards the skb it has allocated
and falls back to normal path, where we'll send as much as possible after
rereading the same data again.  This patch trims SYN+data skb instead -
that way we don't need to copy from the same place twice.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent cacdc7d2

include/net/sock.h

+8 −10
Original line number Diff line number Diff line
@@ -1803,27 +1803,25 @@ static inline void sk_nocaps_add(struct sock *sk, netdev_features_t flags) 
}



static inline int skb_do_copy_data_nocache(struct sock *sk, struct sk_buff *skb,

					   char __user *from, char *to,

					   struct iov_iter *from, char *to,

					   int copy, int offset)

{

	if (skb->ip_summed == CHECKSUM_NONE) {

		int err = 0;

		__wsum csum = csum_and_copy_from_user(from, to, copy, 0, &err);

		if (err)

			return err;

		__wsum csum = 0;

		if (csum_and_copy_from_iter(to, copy, &csum, from) != copy)

			return -EFAULT;

		skb->csum = csum_block_add(skb->csum, csum, offset);

	} else if (sk->sk_route_caps & NETIF_F_NOCACHE_COPY) {

		if (!access_ok(VERIFY_READ, from, copy) ||

		    __copy_from_user_nocache(to, from, copy))

		if (copy_from_iter_nocache(to, copy, from) != copy)

			return -EFAULT;

	} else if (copy_from_user(to, from, copy))

	} else if (copy_from_iter(to, copy, from) != copy)

		return -EFAULT;



	return 0;

}



static inline int skb_add_data_nocache(struct sock *sk, struct sk_buff *skb,

				       char __user *from, int copy)

				       struct iov_iter *from, int copy)

{

	int err, offset = skb->len;
@@ -1835,7 +1833,7 @@ static inline int skb_add_data_nocache(struct sock *sk, struct sk_buff *skb, 
	return err;

}



static inline int skb_copy_to_page_nocache(struct sock *sk, char __user *from,

static inline int skb_copy_to_page_nocache(struct sock *sk, struct iov_iter *from,

					   struct sk_buff *skb,

					   struct page *page,

					   int off, int copy)

net/ipv4/tcp.c

+106 −127
Original line number Diff line number Diff line
@@ -1067,11 +1067,10 @@ static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, 
int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,

		size_t size)

{

	const struct iovec *iov;

	struct tcp_sock *tp = tcp_sk(sk);

	struct sk_buff *skb;

	int iovlen, flags, err, copied = 0;

	int mss_now = 0, size_goal, copied_syn = 0, offset = 0;

	int flags, err, copied = 0;

	int mss_now = 0, size_goal, copied_syn = 0;

	bool sg;

	long timeo;
@@ -1084,7 +1083,6 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 
			goto out;

		else if (err)

			goto out_err;

		offset = copied_syn;

	}



	timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
@@ -1118,8 +1116,6 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 
	mss_now = tcp_send_mss(sk, &size_goal, flags);



	/* Ok commence sending. */

	iovlen = msg->msg_iter.nr_segs;

	iov = msg->msg_iter.iov;

	copied = 0;



	err = -EPIPE;
@@ -1128,22 +1124,7 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 


	sg = !!(sk->sk_route_caps & NETIF_F_SG);



	while (--iovlen >= 0) {

		size_t seglen = iov->iov_len;

		unsigned char __user *from = iov->iov_base;



		iov++;

		if (unlikely(offset > 0)) {  /* Skip bytes copied in SYN */

			if (offset >= seglen) {

				offset -= seglen;

				continue;

			}

			seglen -= offset;

			from += offset;

			offset = 0;

		}



		while (seglen > 0) {

	while (iov_iter_count(&msg->msg_iter)) {

		int copy = 0;

		int max = size_goal;
@@ -1187,14 +1168,14 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 
		}



		/* Try to append data to the end of skb. */

			if (copy > seglen)

				copy = seglen;

		if (copy > iov_iter_count(&msg->msg_iter))

			copy = iov_iter_count(&msg->msg_iter);



		/* Where to copy to? */

		if (skb_availroom(skb) > 0) {

			/* We have some space in skb head. Superb! */

			copy = min_t(int, copy, skb_availroom(skb));

				err = skb_add_data_nocache(sk, skb, from, copy);

			err = skb_add_data_nocache(sk, skb, &msg->msg_iter, copy);

			if (err)

				goto do_fault;

		} else {
@@ -1219,7 +1200,7 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 
			if (!sk_wmem_schedule(sk, copy))

				goto wait_for_memory;



				err = skb_copy_to_page_nocache(sk, from, skb,

			err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,

						       pfrag->page,

						       pfrag->offset,

						       copy);
@@ -1244,9 +1225,8 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 
		TCP_SKB_CB(skb)->end_seq += copy;

		tcp_skb_pcount_set(skb, 0);



			from += copy;

		copied += copy;

			if ((seglen -= copy) == 0 && iovlen == 0) {

		if (!iov_iter_count(&msg->msg_iter)) {

			tcp_tx_timestamp(sk, skb);

			goto out;

		}
@@ -1273,7 +1253,6 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 


		mss_now = tcp_send_mss(sk, &size_goal, flags);

	}

	}



out:

	if (copied)

net/ipv4/tcp_input.c

+1 −1
Original line number Diff line number Diff line
@@ -4368,7 +4368,7 @@ int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size) 
	if (tcp_try_rmem_schedule(sk, skb, skb->truesize))

		goto err_free;



	if (memcpy_from_msg(skb_put(skb, size), msg, size))

	if (copy_from_iter(skb_put(skb, size), size, &msg->msg_iter) != size)

		goto err_free;



	TCP_SKB_CB(skb)->seq = tcp_sk(sk)->rcv_nxt;

net/ipv4/tcp_output.c

+8 −3
Original line number Diff line number Diff line
@@ -3055,7 +3055,7 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 
{

	struct tcp_sock *tp = tcp_sk(sk);

	struct tcp_fastopen_request *fo = tp->fastopen_req;

	int syn_loss = 0, space, err = 0;

	int syn_loss = 0, space, err = 0, copied;

	unsigned long last_syn_loss = 0;

	struct sk_buff *syn_data;
@@ -3093,11 +3093,16 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 
		goto fallback;

	syn_data->ip_summed = CHECKSUM_PARTIAL;

	memcpy(syn_data->cb, syn->cb, sizeof(syn->cb));

	if (unlikely(memcpy_fromiovecend(skb_put(syn_data, space),

					 fo->data->msg_iter.iov, 0, space))) {

	copied = copy_from_iter(skb_put(syn_data, space), space,

				&fo->data->msg_iter);

	if (unlikely(!copied)) {

		kfree_skb(syn_data);

		goto fallback;

	}

	if (copied != space) {

		skb_trim(syn_data, copied);

		space = copied;

	}



	/* No more data pending in inet_wait_for_connect() */

	if (space == fo->size)