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[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: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
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19773b4923
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@ -327,6 +327,26 @@ static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb,
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}
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}
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/* Constructs common control bits of non-data skb. If SYN/FIN is present,
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* auto increment end seqno.
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*/
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static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
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{
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skb->csum = 0;
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TCP_SKB_CB(skb)->flags = flags;
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TCP_SKB_CB(skb)->sacked = 0;
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skb_shinfo(skb)->gso_segs = 1;
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skb_shinfo(skb)->gso_size = 0;
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skb_shinfo(skb)->gso_type = 0;
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TCP_SKB_CB(skb)->seq = seq;
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if (flags & (TCPCB_FLAG_SYN | TCPCB_FLAG_FIN))
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seq++;
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TCP_SKB_CB(skb)->end_seq = seq;
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}
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static void tcp_build_and_update_options(__be32 *ptr, struct tcp_sock *tp,
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__u32 tstamp, __u8 **md5_hash)
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{
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@ -1864,12 +1884,10 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
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(TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) &&
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tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) {
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if (!pskb_trim(skb, 0)) {
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TCP_SKB_CB(skb)->seq = TCP_SKB_CB(skb)->end_seq - 1;
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skb_shinfo(skb)->gso_segs = 1;
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skb_shinfo(skb)->gso_size = 0;
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skb_shinfo(skb)->gso_type = 0;
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/* Reuse, even though it does some unnecessary work */
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tcp_init_nondata_skb(skb, TCP_SKB_CB(skb)->end_seq - 1,
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TCP_SKB_CB(skb)->flags);
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skb->ip_summed = CHECKSUM_NONE;
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skb->csum = 0;
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}
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}
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@ -2068,16 +2086,9 @@ void tcp_send_fin(struct sock *sk)
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/* Reserve space for headers and prepare control bits. */
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skb_reserve(skb, MAX_TCP_HEADER);
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skb->csum = 0;
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TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_FIN);
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TCP_SKB_CB(skb)->sacked = 0;
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skb_shinfo(skb)->gso_segs = 1;
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skb_shinfo(skb)->gso_size = 0;
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skb_shinfo(skb)->gso_type = 0;
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/* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */
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TCP_SKB_CB(skb)->seq = tp->write_seq;
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TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1;
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tcp_init_nondata_skb(skb, tp->write_seq,
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TCPCB_FLAG_ACK | TCPCB_FLAG_FIN);
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tcp_queue_skb(sk, skb);
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}
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__tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF);
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@ -2101,16 +2112,9 @@ void tcp_send_active_reset(struct sock *sk, gfp_t priority)
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/* Reserve space for headers and prepare control bits. */
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skb_reserve(skb, MAX_TCP_HEADER);
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skb->csum = 0;
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TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_RST);
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TCP_SKB_CB(skb)->sacked = 0;
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skb_shinfo(skb)->gso_segs = 1;
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skb_shinfo(skb)->gso_size = 0;
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skb_shinfo(skb)->gso_type = 0;
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tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk),
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TCPCB_FLAG_ACK | TCPCB_FLAG_RST);
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/* Send it off. */
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TCP_SKB_CB(skb)->seq = tcp_acceptable_seq(sk);
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TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq;
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TCP_SKB_CB(skb)->when = tcp_time_stamp;
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if (tcp_transmit_skb(sk, skb, 0, priority))
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NET_INC_STATS(LINUX_MIB_TCPABORTFAILED);
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@ -2198,12 +2202,11 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
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TCP_ECN_make_synack(req, th);
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th->source = inet_sk(sk)->sport;
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th->dest = ireq->rmt_port;
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TCP_SKB_CB(skb)->seq = tcp_rsk(req)->snt_isn;
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TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1;
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TCP_SKB_CB(skb)->sacked = 0;
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skb_shinfo(skb)->gso_segs = 1;
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skb_shinfo(skb)->gso_size = 0;
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skb_shinfo(skb)->gso_type = 0;
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/* Setting of flags are superfluous here for callers (and ECE is
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* not even correctly set)
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*/
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tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn,
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TCPCB_FLAG_SYN | TCPCB_FLAG_ACK);
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th->seq = htonl(TCP_SKB_CB(skb)->seq);
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th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1);
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if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */
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@ -2235,7 +2238,6 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
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NULL)
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);
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skb->csum = 0;
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th->doff = (tcp_header_size >> 2);
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TCP_INC_STATS(TCP_MIB_OUTSEGS);
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@ -2327,16 +2329,9 @@ int tcp_connect(struct sock *sk)
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/* Reserve space for headers. */
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skb_reserve(buff, MAX_TCP_HEADER);
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TCP_SKB_CB(buff)->flags = TCPCB_FLAG_SYN;
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TCP_ECN_send_syn(sk, buff);
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TCP_SKB_CB(buff)->sacked = 0;
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skb_shinfo(buff)->gso_segs = 1;
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skb_shinfo(buff)->gso_size = 0;
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skb_shinfo(buff)->gso_type = 0;
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buff->csum = 0;
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tp->snd_nxt = tp->write_seq;
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TCP_SKB_CB(buff)->seq = tp->write_seq++;
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TCP_SKB_CB(buff)->end_seq = tp->write_seq;
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tcp_init_nondata_skb(buff, tp->write_seq++, TCPCB_FLAG_SYN);
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TCP_ECN_send_syn(sk, buff);
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/* Send it off. */
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TCP_SKB_CB(buff)->when = tcp_time_stamp;
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@ -2441,15 +2436,9 @@ void tcp_send_ack(struct sock *sk)
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/* Reserve space for headers and prepare control bits. */
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skb_reserve(buff, MAX_TCP_HEADER);
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buff->csum = 0;
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TCP_SKB_CB(buff)->flags = TCPCB_FLAG_ACK;
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TCP_SKB_CB(buff)->sacked = 0;
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skb_shinfo(buff)->gso_segs = 1;
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skb_shinfo(buff)->gso_size = 0;
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skb_shinfo(buff)->gso_type = 0;
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tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPCB_FLAG_ACK);
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/* Send it off, this clears delayed acks for us. */
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TCP_SKB_CB(buff)->seq = TCP_SKB_CB(buff)->end_seq = tcp_acceptable_seq(sk);
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TCP_SKB_CB(buff)->when = tcp_time_stamp;
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tcp_transmit_skb(sk, buff, 0, GFP_ATOMIC);
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}
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@ -2477,19 +2466,11 @@ static int tcp_xmit_probe_skb(struct sock *sk, int urgent)
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/* Reserve space for headers and set control bits. */
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skb_reserve(skb, MAX_TCP_HEADER);
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skb->csum = 0;
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TCP_SKB_CB(skb)->flags = TCPCB_FLAG_ACK;
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TCP_SKB_CB(skb)->sacked = 0;
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skb_shinfo(skb)->gso_segs = 1;
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skb_shinfo(skb)->gso_size = 0;
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skb_shinfo(skb)->gso_type = 0;
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/* Use a previous sequence. This should cause the other
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* end to send an ack. Don't queue or clone SKB, just
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* send it.
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*/
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TCP_SKB_CB(skb)->seq = tp->snd_una - !urgent;
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TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq;
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tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPCB_FLAG_ACK);
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TCP_SKB_CB(skb)->when = tcp_time_stamp;
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return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC);
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}
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