From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yuchung Cheng Subject: Re: [PATCH net-next 2/2] tcp: remove TCP_SKB_CB(skb)->when Date: Fri, 5 Sep 2014 15:49:31 -0700 Message-ID: References: <1409956413-29472-1-git-send-email-edumazet@google.com> <1409956413-29472-3-git-send-email-edumazet@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: "David S. Miller" , netdev , Neal Cardwell To: Eric Dumazet Return-path: Received: from mail-ig0-f180.google.com ([209.85.213.180]:62753 "EHLO mail-ig0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753865AbaIEWuM (ORCPT ); Fri, 5 Sep 2014 18:50:12 -0400 Received: by mail-ig0-f180.google.com with SMTP id hn18so154333igb.13 for ; Fri, 05 Sep 2014 15:50:11 -0700 (PDT) In-Reply-To: <1409956413-29472-3-git-send-email-edumazet@google.com> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, Sep 5, 2014 at 3:33 PM, Eric Dumazet wrote: > After commit 740b0f1841f6 ("tcp: switch rtt estimations to usec resolution"), > we no longer need to maintain timestamps in two different fields. > > TCP_SKB_CB(skb)->when can be removed, as same information sits in skb_mstamp.stamp_jiffies > > Signed-off-by: Eric Dumazet Acked-by: Yuchung Cheng > --- > include/net/tcp.h | 13 +++++++------ > net/ipv4/tcp_input.c | 3 ++- > net/ipv4/tcp_ipv4.c | 5 +++-- > net/ipv4/tcp_output.c | 39 ++++++++++++++++----------------------- > net/ipv4/tcp_timer.c | 7 +++---- > 5 files changed, 31 insertions(+), 36 deletions(-) > > diff --git a/include/net/tcp.h b/include/net/tcp.h > index 0cd7d2c65dc0..a4201ef216e8 100644 > --- a/include/net/tcp.h > +++ b/include/net/tcp.h > @@ -672,6 +672,12 @@ void tcp_send_window_probe(struct sock *sk); > */ > #define tcp_time_stamp ((__u32)(jiffies)) > > +static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) > +{ > + return skb->skb_mstamp.stamp_jiffies; > +} > + > + > #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) > > #define TCPHDR_FIN 0x01 > @@ -698,12 +704,7 @@ struct tcp_skb_cb { > } header; /* For incoming frames */ > __u32 seq; /* Starting sequence number */ > __u32 end_seq; /* SEQ + FIN + SYN + datalen */ > - union { > - /* used in output path */ > - __u32 when; /* used to compute rtt's */ > - /* used in input path */ > - __u32 tcp_tw_isn; /* isn chosen by tcp_timewait_state_process() */ > - }; > + __u32 tcp_tw_isn; /* isn chosen by tcp_timewait_state_process() */ > __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ > > __u8 sacked; /* State flags for SACK/FACK. */ > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c > index 9c8b9f1dcf69..f97003ad0af5 100644 > --- a/net/ipv4/tcp_input.c > +++ b/net/ipv4/tcp_input.c > @@ -2967,7 +2967,8 @@ void tcp_rearm_rto(struct sock *sk) > if (icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS || > icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) { > struct sk_buff *skb = tcp_write_queue_head(sk); > - const u32 rto_time_stamp = TCP_SKB_CB(skb)->when + rto; > + const u32 rto_time_stamp = > + tcp_skb_timestamp(skb) + rto; > s32 delta = (s32)(rto_time_stamp - tcp_time_stamp); > /* delta may not be positive if the socket is locked > * when the retrans timer fires and is rescheduled. > diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c > index 02e6cd29ebf1..3f9bc3f0bba0 100644 > --- a/net/ipv4/tcp_ipv4.c > +++ b/net/ipv4/tcp_ipv4.c > @@ -437,8 +437,9 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info) > skb = tcp_write_queue_head(sk); > BUG_ON(!skb); > > - remaining = icsk->icsk_rto - min(icsk->icsk_rto, > - tcp_time_stamp - TCP_SKB_CB(skb)->when); > + remaining = icsk->icsk_rto - > + min(icsk->icsk_rto, > + tcp_time_stamp - tcp_skb_timestamp(skb)); > > if (remaining) { > inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, > diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c > index 5a7c41fbc6d3..3b22dcb7bb5c 100644 > --- a/net/ipv4/tcp_output.c > +++ b/net/ipv4/tcp_output.c > @@ -550,7 +550,7 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, > > if (likely(sysctl_tcp_timestamps && *md5 == NULL)) { > opts->options |= OPTION_TS; > - opts->tsval = TCP_SKB_CB(skb)->when + tp->tsoffset; > + opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; > opts->tsecr = tp->rx_opt.ts_recent; > remaining -= TCPOLEN_TSTAMP_ALIGNED; > } > @@ -618,7 +618,7 @@ static unsigned int tcp_synack_options(struct sock *sk, > } > if (likely(ireq->tstamp_ok)) { > opts->options |= OPTION_TS; > - opts->tsval = TCP_SKB_CB(skb)->when; > + opts->tsval = tcp_skb_timestamp(skb); > opts->tsecr = req->ts_recent; > remaining -= TCPOLEN_TSTAMP_ALIGNED; > } > @@ -647,7 +647,6 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb > struct tcp_out_options *opts, > struct tcp_md5sig_key **md5) > { > - struct tcp_skb_cb *tcb = skb ? TCP_SKB_CB(skb) : NULL; > struct tcp_sock *tp = tcp_sk(sk); > unsigned int size = 0; > unsigned int eff_sacks; > @@ -666,7 +665,7 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb > > if (likely(tp->rx_opt.tstamp_ok)) { > opts->options |= OPTION_TS; > - opts->tsval = tcb ? tcb->when + tp->tsoffset : 0; > + opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; > opts->tsecr = tp->rx_opt.ts_recent; > size += TCPOLEN_TSTAMP_ALIGNED; > } > @@ -886,8 +885,6 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, > skb = skb_clone(skb, gfp_mask); > if (unlikely(!skb)) > return -ENOBUFS; > - /* Our usage of tstamp should remain private */ > - skb->tstamp.tv64 = 0; > } > > inet = inet_sk(sk); > @@ -975,7 +972,10 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, > TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, > tcp_skb_pcount(skb)); > > + /* Our usage of tstamp should remain private */ > + skb->tstamp.tv64 = 0; > err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl); > + > if (likely(err <= 0)) > return err; > > @@ -1149,7 +1149,6 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, > /* Looks stupid, but our code really uses when of > * skbs, which it never sent before. --ANK > */ Remove the comment above too? > - TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when; > buff->tstamp = skb->tstamp; > tcp_fragment_tstamp(skb, buff); > > @@ -1874,8 +1873,8 @@ static int tcp_mtu_probe(struct sock *sk) > tcp_init_tso_segs(sk, nskb, nskb->len); > > /* We're ready to send. If this fails, the probe will > - * be resegmented into mss-sized pieces by tcp_write_xmit(). */ > - TCP_SKB_CB(nskb)->when = tcp_time_stamp; > + * be resegmented into mss-sized pieces by tcp_write_xmit(). > + */ > if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { > /* Decrement cwnd here because we are sending > * effectively two packets. */ > @@ -1935,8 +1934,8 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, > BUG_ON(!tso_segs); > > if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { > - /* "when" is used as a start point for the retransmit timer */ > - TCP_SKB_CB(skb)->when = tcp_time_stamp; > + /* "skb_mstamp" is used as a start point for the retransmit timer */ > + skb_mstamp_get(&skb->skb_mstamp); > goto repair; /* Skip network transmission */ > } > > @@ -2000,8 +1999,6 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, > unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) > break; > > - TCP_SKB_CB(skb)->when = tcp_time_stamp; > - > if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) > break; > > @@ -2499,7 +2496,6 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) > /* Make a copy, if the first transmission SKB clone we made > * is still in somebody's hands, else make a clone. > */ > - TCP_SKB_CB(skb)->when = tcp_time_stamp; > > /* make sure skb->data is aligned on arches that require it > * and check if ack-trimming & collapsing extended the headroom > @@ -2544,7 +2540,7 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) > > /* Save stamp of the first retransmit. */ > if (!tp->retrans_stamp) > - tp->retrans_stamp = TCP_SKB_CB(skb)->when; > + tp->retrans_stamp = tcp_skb_timestamp(skb); > > /* snd_nxt is stored to detect loss of retransmitted segment, > * see tcp_input.c tcp_sacktag_write_queue(). > @@ -2752,7 +2748,6 @@ void tcp_send_active_reset(struct sock *sk, gfp_t priority) > tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), > TCPHDR_ACK | TCPHDR_RST); > /* Send it off. */ > - TCP_SKB_CB(skb)->when = tcp_time_stamp; > if (tcp_transmit_skb(sk, skb, 0, priority)) > NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); > > @@ -2791,7 +2786,6 @@ int tcp_send_synack(struct sock *sk) > TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; > TCP_ECN_send_synack(tcp_sk(sk), skb); > } > - TCP_SKB_CB(skb)->when = tcp_time_stamp; > return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); > } > > @@ -2835,10 +2829,10 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, > memset(&opts, 0, sizeof(opts)); > #ifdef CONFIG_SYN_COOKIES > if (unlikely(req->cookie_ts)) > - TCP_SKB_CB(skb)->when = cookie_init_timestamp(req); > + skb->skb_mstamp.stamp_jiffies = cookie_init_timestamp(req); > else > #endif > - TCP_SKB_CB(skb)->when = tcp_time_stamp; > + skb_mstamp_get(&skb->skb_mstamp); > tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, &md5, > foc) + sizeof(*th); > > @@ -3086,7 +3080,7 @@ int tcp_connect(struct sock *sk) > skb_reserve(buff, MAX_TCP_HEADER); > > tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); > - tp->retrans_stamp = TCP_SKB_CB(buff)->when = tcp_time_stamp; > + tp->retrans_stamp = tcp_time_stamp; > tcp_connect_queue_skb(sk, buff); > TCP_ECN_send_syn(sk, buff); > > @@ -3194,7 +3188,7 @@ void tcp_send_ack(struct sock *sk) > tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); > > /* Send it off, this clears delayed acks for us. */ > - TCP_SKB_CB(buff)->when = tcp_time_stamp; > + skb_mstamp_get(&buff->skb_mstamp); > tcp_transmit_skb(sk, buff, 0, sk_gfp_atomic(sk, GFP_ATOMIC)); > } > > @@ -3226,7 +3220,7 @@ static int tcp_xmit_probe_skb(struct sock *sk, int urgent) > * send it. > */ > tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); > - TCP_SKB_CB(skb)->when = tcp_time_stamp; > + skb_mstamp_get(&skb->skb_mstamp); > return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); > } > > @@ -3270,7 +3264,6 @@ int tcp_write_wakeup(struct sock *sk) > tcp_set_skb_tso_segs(sk, skb, mss); > > TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; > - TCP_SKB_CB(skb)->when = tcp_time_stamp; > err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); > if (!err) > tcp_event_new_data_sent(sk, skb); > diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c > index df90cd1ce37f..a339e7ba05a4 100644 > --- a/net/ipv4/tcp_timer.c > +++ b/net/ipv4/tcp_timer.c > @@ -135,10 +135,9 @@ static bool retransmits_timed_out(struct sock *sk, > if (!inet_csk(sk)->icsk_retransmits) > return false; > > - if (unlikely(!tcp_sk(sk)->retrans_stamp)) > - start_ts = TCP_SKB_CB(tcp_write_queue_head(sk))->when; > - else > - start_ts = tcp_sk(sk)->retrans_stamp; > + start_ts = tcp_sk(sk)->retrans_stamp; > + if (unlikely(!start_ts)) > + start_ts = tcp_skb_timestamp(tcp_write_queue_head(sk)); > > if (likely(timeout == 0)) { > linear_backoff_thresh = ilog2(TCP_RTO_MAX/rto_base); > -- > 2.1.0.rc2.206.gedb03e5 >