From e870a8efcddaaa3da7e180b6ae21239fb96aa2bb Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ilpo=20J=C3=A4rvinen?= Date: Thu, 3 Jan 2008 20:39:01 -0800 Subject: [PATCH] [TCP]: Perform setting of common control fields in one place MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 91 +++++++++++++++++-------------------------- 1 file changed, 36 insertions(+), 55 deletions(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 6c7cd0a9098..89f0188885c 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -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, __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) && tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) { if (!pskb_trim(skb, 0)) { - TCP_SKB_CB(skb)->seq = TCP_SKB_CB(skb)->end_seq - 1; - skb_shinfo(skb)->gso_segs = 1; - skb_shinfo(skb)->gso_size = 0; - skb_shinfo(skb)->gso_type = 0; + /* Reuse, even though it does some unnecessary work */ + tcp_init_nondata_skb(skb, TCP_SKB_CB(skb)->end_seq - 1, + TCP_SKB_CB(skb)->flags); 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. */ 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(). */ - TCP_SKB_CB(skb)->seq = tp->write_seq; - TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1; + tcp_init_nondata_skb(skb, tp->write_seq, + TCPCB_FLAG_ACK | TCPCB_FLAG_FIN); tcp_queue_skb(sk, skb); } __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. */ skb_reserve(skb, MAX_TCP_HEADER); - skb->csum = 0; - TCP_SKB_CB(skb)->flags = (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; - + tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), + TCPCB_FLAG_ACK | TCPCB_FLAG_RST); /* 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; if (tcp_transmit_skb(sk, skb, 0, priority)) 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); th->source = inet_sk(sk)->sport; th->dest = ireq->rmt_port; - TCP_SKB_CB(skb)->seq = tcp_rsk(req)->snt_isn; - TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1; - TCP_SKB_CB(skb)->sacked = 0; - skb_shinfo(skb)->gso_segs = 1; - skb_shinfo(skb)->gso_size = 0; - skb_shinfo(skb)->gso_type = 0; + /* Setting of flags are superfluous here for callers (and ECE is + * not even correctly set) + */ + tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, + TCPCB_FLAG_SYN | TCPCB_FLAG_ACK); th->seq = htonl(TCP_SKB_CB(skb)->seq); th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1); 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) ); - skb->csum = 0; th->doff = (tcp_header_size >> 2); TCP_INC_STATS(TCP_MIB_OUTSEGS); @@ -2327,16 +2329,9 @@ int tcp_connect(struct sock *sk) /* Reserve space for headers. */ 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; - TCP_SKB_CB(buff)->seq = tp->write_seq++; - TCP_SKB_CB(buff)->end_seq = tp->write_seq; + tcp_init_nondata_skb(buff, tp->write_seq++, TCPCB_FLAG_SYN); + TCP_ECN_send_syn(sk, buff); /* Send it off. */ 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. */ skb_reserve(buff, MAX_TCP_HEADER); - buff->csum = 0; - 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; + tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPCB_FLAG_ACK); /* 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_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. */ 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 * end to send an ack. Don't queue or clone SKB, just * send it. */ - TCP_SKB_CB(skb)->seq = tp->snd_una - !urgent; - TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq; + tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPCB_FLAG_ACK); TCP_SKB_CB(skb)->when = tcp_time_stamp; return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); } -- 2.41.0