tcp: remove TCP_SKB_CB(skb)->when

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 <edumazet@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 0cd7d2c..a4201ef 100644 (file)
--- 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 9c8b9f1..f97003a 100644 (file)
--- 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 02e6cd2..3f9bc3f 100644 (file)
--- 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 5a7c41f..3b22dcb 100644 (file)
--- 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
         */
-       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 df90cd1..a339e7b 100644 (file)
--- 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);