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Commit e870a8ef authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by David S. Miller
Browse files

[TCP]: Perform setting of common control fields in one place 



In case of segments which are purely for control without any
data (SYN/ACK/FIN/RST), many fields are set to common values
in multiple places.

i386 results:

$ gcc --version
gcc (GCC) 4.1.2 20070626 (Red Hat 4.1.2-13)

$ codiff tcp_output.o.old tcp_output.o.new
net/ipv4/tcp_output.c:
  tcp_xmit_probe_skb    |  -48
  tcp_send_ack          |  -56
  tcp_retransmit_skb    |  -79
  tcp_connect           |  -43
  tcp_send_active_reset |  -35
  tcp_make_synack       |  -42
  tcp_send_fin          |  -48
 7 functions changed, 351 bytes removed

net/ipv4/tcp_output.c:
  tcp_init_nondata_skb |  +90
 1 function changed, 90 bytes added

tcp_output.o.mid:
 8 functions changed, 90 bytes added, 351 bytes removed, diff: -261

Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 19773b49

net/ipv4/tcp_output.c

+36 −55
Original line number Original line Diff line number Diff line
@@ -327,6 +327,26 @@ static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb, 
	}

	}

}

}





/* Constructs common control bits of non-data skb. If SYN/FIN is present,

 * auto increment end seqno.

 */

static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)

{

	skb->csum = 0;



	TCP_SKB_CB(skb)->flags = flags;

	TCP_SKB_CB(skb)->sacked = 0;



	skb_shinfo(skb)->gso_segs = 1;

	skb_shinfo(skb)->gso_size = 0;

	skb_shinfo(skb)->gso_type = 0;



	TCP_SKB_CB(skb)->seq = seq;

	if (flags & (TCPCB_FLAG_SYN | TCPCB_FLAG_FIN))

		seq++;

	TCP_SKB_CB(skb)->end_seq = seq;

}



static void tcp_build_and_update_options(__be32 *ptr, struct tcp_sock *tp,

static void tcp_build_and_update_options(__be32 *ptr, struct tcp_sock *tp,

					 __u32 tstamp, __u8 **md5_hash)

					 __u32 tstamp, __u8 **md5_hash)

{

{
@@ -1864,12 +1884,10 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 
	    (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) &&

	    (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) &&

	    tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) {

	    tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) {

		if (!pskb_trim(skb, 0)) {

		if (!pskb_trim(skb, 0)) {

			TCP_SKB_CB(skb)->seq = TCP_SKB_CB(skb)->end_seq - 1;

			/* Reuse, even though it does some unnecessary work */

			skb_shinfo(skb)->gso_segs = 1;

			tcp_init_nondata_skb(skb, TCP_SKB_CB(skb)->end_seq - 1,

			skb_shinfo(skb)->gso_size = 0;

					     TCP_SKB_CB(skb)->flags);

			skb_shinfo(skb)->gso_type = 0;

			skb->ip_summed = CHECKSUM_NONE;

			skb->ip_summed = CHECKSUM_NONE;

			skb->csum = 0;

		}

		}

	}

	}
@@ -2068,16 +2086,9 @@ void tcp_send_fin(struct sock *sk) 




		/* Reserve space for headers and prepare control bits. */

		/* Reserve space for headers and prepare control bits. */

		skb_reserve(skb, MAX_TCP_HEADER);

		skb_reserve(skb, MAX_TCP_HEADER);

		skb->csum = 0;

		TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_FIN);

		TCP_SKB_CB(skb)->sacked = 0;

		skb_shinfo(skb)->gso_segs = 1;

		skb_shinfo(skb)->gso_size = 0;

		skb_shinfo(skb)->gso_type = 0;



		/* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */

		/* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */

		TCP_SKB_CB(skb)->seq = tp->write_seq;

		tcp_init_nondata_skb(skb, tp->write_seq,

		TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1;

				     TCPCB_FLAG_ACK | TCPCB_FLAG_FIN);

		tcp_queue_skb(sk, skb);

		tcp_queue_skb(sk, skb);

	}

	}

	__tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF);

	__tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF);
@@ -2101,16 +2112,9 @@ void tcp_send_active_reset(struct sock *sk, gfp_t priority) 




	/* Reserve space for headers and prepare control bits. */

	/* Reserve space for headers and prepare control bits. */

	skb_reserve(skb, MAX_TCP_HEADER);

	skb_reserve(skb, MAX_TCP_HEADER);

	skb->csum = 0;

	tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk),

	TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_RST);

			     TCPCB_FLAG_ACK | TCPCB_FLAG_RST);

	TCP_SKB_CB(skb)->sacked = 0;

	skb_shinfo(skb)->gso_segs = 1;

	skb_shinfo(skb)->gso_size = 0;

	skb_shinfo(skb)->gso_type = 0;



	/* Send it off. */

	/* Send it off. */

	TCP_SKB_CB(skb)->seq = tcp_acceptable_seq(sk);

	TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq;

	TCP_SKB_CB(skb)->when = tcp_time_stamp;

	TCP_SKB_CB(skb)->when = tcp_time_stamp;

	if (tcp_transmit_skb(sk, skb, 0, priority))

	if (tcp_transmit_skb(sk, skb, 0, priority))

		NET_INC_STATS(LINUX_MIB_TCPABORTFAILED);

		NET_INC_STATS(LINUX_MIB_TCPABORTFAILED);
@@ -2198,12 +2202,11 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, 
	TCP_ECN_make_synack(req, th);

	TCP_ECN_make_synack(req, th);

	th->source = inet_sk(sk)->sport;

	th->source = inet_sk(sk)->sport;

	th->dest = ireq->rmt_port;

	th->dest = ireq->rmt_port;

	TCP_SKB_CB(skb)->seq = tcp_rsk(req)->snt_isn;

	/* Setting of flags are superfluous here for callers (and ECE is

	TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1;

	 * not even correctly set)

	TCP_SKB_CB(skb)->sacked = 0;

	 */

	skb_shinfo(skb)->gso_segs = 1;

	tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn,

	skb_shinfo(skb)->gso_size = 0;

			     TCPCB_FLAG_SYN | TCPCB_FLAG_ACK);

	skb_shinfo(skb)->gso_type = 0;

	th->seq = htonl(TCP_SKB_CB(skb)->seq);

	th->seq = htonl(TCP_SKB_CB(skb)->seq);

	th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1);

	th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1);

	if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */

	if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */
@@ -2235,7 +2238,6 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, 
			       NULL)

			       NULL)

			      );

			      );





	skb->csum = 0;

	th->doff = (tcp_header_size >> 2);

	th->doff = (tcp_header_size >> 2);

	TCP_INC_STATS(TCP_MIB_OUTSEGS);

	TCP_INC_STATS(TCP_MIB_OUTSEGS);
@@ -2327,16 +2329,9 @@ int tcp_connect(struct sock *sk) 
	/* Reserve space for headers. */

	/* Reserve space for headers. */

	skb_reserve(buff, MAX_TCP_HEADER);

	skb_reserve(buff, MAX_TCP_HEADER);





	TCP_SKB_CB(buff)->flags = TCPCB_FLAG_SYN;

	TCP_ECN_send_syn(sk, buff);

	TCP_SKB_CB(buff)->sacked = 0;

	skb_shinfo(buff)->gso_segs = 1;

	skb_shinfo(buff)->gso_size = 0;

	skb_shinfo(buff)->gso_type = 0;

	buff->csum = 0;

	tp->snd_nxt = tp->write_seq;

	tp->snd_nxt = tp->write_seq;

	TCP_SKB_CB(buff)->seq = tp->write_seq++;

	tcp_init_nondata_skb(buff, tp->write_seq++, TCPCB_FLAG_SYN);

	TCP_SKB_CB(buff)->end_seq = tp->write_seq;

	TCP_ECN_send_syn(sk, buff);





	/* Send it off. */

	/* Send it off. */

	TCP_SKB_CB(buff)->when = tcp_time_stamp;

	TCP_SKB_CB(buff)->when = tcp_time_stamp;
@@ -2441,15 +2436,9 @@ void tcp_send_ack(struct sock *sk) 




	/* Reserve space for headers and prepare control bits. */

	/* Reserve space for headers and prepare control bits. */

	skb_reserve(buff, MAX_TCP_HEADER);

	skb_reserve(buff, MAX_TCP_HEADER);

	buff->csum = 0;

	tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPCB_FLAG_ACK);

	TCP_SKB_CB(buff)->flags = TCPCB_FLAG_ACK;

	TCP_SKB_CB(buff)->sacked = 0;

	skb_shinfo(buff)->gso_segs = 1;

	skb_shinfo(buff)->gso_size = 0;

	skb_shinfo(buff)->gso_type = 0;





	/* Send it off, this clears delayed acks for us. */

	/* Send it off, this clears delayed acks for us. */

	TCP_SKB_CB(buff)->seq = TCP_SKB_CB(buff)->end_seq = tcp_acceptable_seq(sk);

	TCP_SKB_CB(buff)->when = tcp_time_stamp;

	TCP_SKB_CB(buff)->when = tcp_time_stamp;

	tcp_transmit_skb(sk, buff, 0, GFP_ATOMIC);

	tcp_transmit_skb(sk, buff, 0, GFP_ATOMIC);

}

}
@@ -2477,19 +2466,11 @@ static int tcp_xmit_probe_skb(struct sock *sk, int urgent) 




	/* Reserve space for headers and set control bits. */

	/* Reserve space for headers and set control bits. */

	skb_reserve(skb, MAX_TCP_HEADER);

	skb_reserve(skb, MAX_TCP_HEADER);

	skb->csum = 0;

	TCP_SKB_CB(skb)->flags = TCPCB_FLAG_ACK;

	TCP_SKB_CB(skb)->sacked = 0;

	skb_shinfo(skb)->gso_segs = 1;

	skb_shinfo(skb)->gso_size = 0;

	skb_shinfo(skb)->gso_type = 0;



	/* Use a previous sequence.  This should cause the other

	/* Use a previous sequence.  This should cause the other

	 * end to send an ack.  Don't queue or clone SKB, just

	 * end to send an ack.  Don't queue or clone SKB, just

	 * send it.

	 * send it.

	 */

	 */

	TCP_SKB_CB(skb)->seq = tp->snd_una - !urgent;

	tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPCB_FLAG_ACK);

	TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq;

	TCP_SKB_CB(skb)->when = tcp_time_stamp;

	TCP_SKB_CB(skb)->when = tcp_time_stamp;

	return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC);

	return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC);

}

}