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Commit 0c54b85f authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by David S. Miller
Browse files

tcp: simplify tcp_current_mss 



There's very little need for most of the callsites to get
tp->xmit_goal_size updated. That will cost us divide as is,
so slice the function in two. Also, the only users of the
tp->xmit_goal_size are directly behind tcp_current_mss(),
so there's no need to store that variable into tcp_sock
at all! The drop of xmit_goal_size currently leaves 16-bit
hole and some reorganization would again be necessary to
change that (but I'm aiming to fill that hole with u16
xmit_goal_size_segs to cache the results of the remaining
divide to get that tso on regression).

Bring xmit_goal_size parts into tcp.c

Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 72211e90

include/linux/tcp.h

+0 −1
Original line number Diff line number Diff line
@@ -248,7 +248,6 @@ struct tcp_sock { 
	/* inet_connection_sock has to be the first member of tcp_sock */

	struct inet_connection_sock	inet_conn;

	u16	tcp_header_len;	/* Bytes of tcp header to send		*/

	u16	xmit_size_goal;	/* Goal for segmenting output packets	*/



/*

 *	Header prediction flags

include/net/tcp.h

+11 −2
Original line number Diff line number Diff line
@@ -481,7 +481,16 @@ static inline void tcp_clear_xmit_timers(struct sock *sk) 
}



extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);

extern unsigned int tcp_current_mss(struct sock *sk, int large);

extern unsigned int tcp_current_mss(struct sock *sk);



/* Bound MSS / TSO packet size with the half of the window */

static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)

{

	if (tp->max_window && pktsize > (tp->max_window >> 1))

		return max(tp->max_window >> 1, 68U - tp->tcp_header_len);

	else

		return pktsize;

}



/* tcp.c */

extern void tcp_get_info(struct sock *, struct tcp_info *);
@@ -822,7 +831,7 @@ static inline void tcp_push_pending_frames(struct sock *sk) 
{

	struct tcp_sock *tp = tcp_sk(sk);



	__tcp_push_pending_frames(sk, tcp_current_mss(sk, 1), tp->nonagle);

	__tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);

}



static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)

net/ipv4/tcp.c

+35 −8
Original line number Diff line number Diff line
@@ -661,6 +661,37 @@ struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp) 
	return NULL;

}



static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,

				       int large_allowed)

{

	struct tcp_sock *tp = tcp_sk(sk);

	u32 xmit_size_goal;



	xmit_size_goal = mss_now;



	if (large_allowed && sk_can_gso(sk)) {

		xmit_size_goal = ((sk->sk_gso_max_size - 1) -

				  inet_csk(sk)->icsk_af_ops->net_header_len -

				  inet_csk(sk)->icsk_ext_hdr_len -

				  tp->tcp_header_len);



		xmit_size_goal = tcp_bound_to_half_wnd(tp, xmit_size_goal);

		xmit_size_goal -= (xmit_size_goal % mss_now);

	}



	return xmit_size_goal;

}



static int tcp_send_mss(struct sock *sk, int *size_goal, int flags)

{

	int mss_now;



	mss_now = tcp_current_mss(sk);

	*size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));



	return mss_now;

}



static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,

			 size_t psize, int flags)

{
@@ -677,8 +708,7 @@ static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffse 


	clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);



	mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));

	size_goal = tp->xmit_size_goal;

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

	copied = 0;



	err = -EPIPE;
@@ -761,8 +791,7 @@ wait_for_memory: 
		if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)

			goto do_error;



		mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));

		size_goal = tp->xmit_size_goal;

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

	}



out:
@@ -844,8 +873,7 @@ int tcp_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg, 
	/* This should be in poll */

	clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);



	mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));

	size_goal = tp->xmit_size_goal;

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



	/* Ok commence sending. */

	iovlen = msg->msg_iovlen;
@@ -1007,8 +1035,7 @@ wait_for_memory: 
			if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)

				goto do_error;



			mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));

			size_goal = tp->xmit_size_goal;

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

		}

	}

net/ipv4/tcp_input.c

+1 −1
Original line number Diff line number Diff line
@@ -2864,7 +2864,7 @@ void tcp_simple_retransmit(struct sock *sk) 
	const struct inet_connection_sock *icsk = inet_csk(sk);

	struct tcp_sock *tp = tcp_sk(sk);

	struct sk_buff *skb;

	unsigned int mss = tcp_current_mss(sk, 0);

	unsigned int mss = tcp_current_mss(sk);

	u32 prior_lost = tp->lost_out;



	tcp_for_write_queue(skb, sk) {

net/ipv4/tcp_output.c

+7 −34
Original line number Diff line number Diff line
@@ -921,7 +921,7 @@ int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 
	 * factor and mss.

	 */

	if (tcp_skb_pcount(skb) > 1)

		tcp_set_skb_tso_segs(sk, skb, tcp_current_mss(sk, 1));

		tcp_set_skb_tso_segs(sk, skb, tcp_current_mss(sk));



	return 0;

}
@@ -982,15 +982,6 @@ void tcp_mtup_init(struct sock *sk) 
	icsk->icsk_mtup.probe_size = 0;

}



/* Bound MSS / TSO packet size with the half of the window */

static int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)

{

	if (tp->max_window && pktsize > (tp->max_window >> 1))

		return max(tp->max_window >> 1, 68U - tp->tcp_header_len);

	else

		return pktsize;

}



/* This function synchronize snd mss to current pmtu/exthdr set.



   tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts
@@ -1037,22 +1028,17 @@ unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 
/* Compute the current effective MSS, taking SACKs and IP options,

 * and even PMTU discovery events into account.

 */

unsigned int tcp_current_mss(struct sock *sk, int large_allowed)

unsigned int tcp_current_mss(struct sock *sk)

{

	struct tcp_sock *tp = tcp_sk(sk);

	struct dst_entry *dst = __sk_dst_get(sk);

	u32 mss_now;

	u16 xmit_size_goal;

	int doing_tso = 0;

	unsigned header_len;

	struct tcp_out_options opts;

	struct tcp_md5sig_key *md5;



	mss_now = tp->mss_cache;



	if (large_allowed && sk_can_gso(sk))

		doing_tso = 1;



	if (dst) {

		u32 mtu = dst_mtu(dst);

		if (mtu != inet_csk(sk)->icsk_pmtu_cookie)
@@ -1070,19 +1056,6 @@ unsigned int tcp_current_mss(struct sock *sk, int large_allowed) 
		mss_now -= delta;

	}



	xmit_size_goal = mss_now;



	if (doing_tso) {

		xmit_size_goal = ((sk->sk_gso_max_size - 1) -

				  inet_csk(sk)->icsk_af_ops->net_header_len -

				  inet_csk(sk)->icsk_ext_hdr_len -

				  tp->tcp_header_len);



		xmit_size_goal = tcp_bound_to_half_wnd(tp, xmit_size_goal);

		xmit_size_goal -= (xmit_size_goal % mss_now);

	}

	tp->xmit_size_goal = xmit_size_goal;



	return mss_now;

}
@@ -1264,7 +1237,7 @@ int tcp_may_send_now(struct sock *sk) 
	struct sk_buff *skb = tcp_send_head(sk);



	return (skb &&

		tcp_snd_test(sk, skb, tcp_current_mss(sk, 1),

		tcp_snd_test(sk, skb, tcp_current_mss(sk),

			     (tcp_skb_is_last(sk, skb) ?

			      tp->nonagle : TCP_NAGLE_PUSH)));

}
@@ -1421,7 +1394,7 @@ static int tcp_mtu_probe(struct sock *sk) 
		return -1;



	/* Very simple search strategy: just double the MSS. */

	mss_now = tcp_current_mss(sk, 0);

	mss_now = tcp_current_mss(sk);

	probe_size = 2 * tp->mss_cache;

	size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache;

	if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high)) {
@@ -1903,7 +1876,7 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 
	if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk))

		return -EHOSTUNREACH; /* Routing failure or similar. */



	cur_mss = tcp_current_mss(sk, 0);

	cur_mss = tcp_current_mss(sk);



	/* If receiver has shrunk his window, and skb is out of

	 * new window, do not retransmit it. The exception is the
@@ -2111,7 +2084,7 @@ void tcp_send_fin(struct sock *sk) 
	 * unsent frames.  But be careful about outgoing SACKS

	 * and IP options.

	 */

	mss_now = tcp_current_mss(sk, 1);

	mss_now = tcp_current_mss(sk);



	if (tcp_send_head(sk) != NULL) {

		TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_FIN;
@@ -2523,7 +2496,7 @@ int tcp_write_wakeup(struct sock *sk) 
	if ((skb = tcp_send_head(sk)) != NULL &&

	    before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) {

		int err;

		unsigned int mss = tcp_current_mss(sk, 0);

		unsigned int mss = tcp_current_mss(sk);

		unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq;



		if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq))