[CCID3]: Remove two irrelevant states in TX feedback handling

 * the NO_SENT state is only triggered in bidirectional mode,
   costing unnecessary processing.
 * the TERM (terminating) state is irrelevant.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 84 insertions, 89 deletions

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index e31560daa0b9..a93a556ad03d 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -402,112 +402,107 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
         if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK ||
               DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK))
                 return;
+        /* ... and only in the established state */
+        if (hctx->ccid3hctx_state != TFRC_SSTATE_FBACK &&
+            hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK)
+                return;
 
         opt_recv = &hctx->ccid3hctx_options_received;
+        now = ktime_get_real();
 
-        switch (hctx->ccid3hctx_state) {
-        case TFRC_SSTATE_NO_FBACK:
-        case TFRC_SSTATE_FBACK:
-                now = ktime_get_real();
-
-                /* estimate RTT from history if ACK number is valid */
-                r_sample = tfrc_tx_hist_rtt(hctx->ccid3hctx_hist,
-                                            DCCP_SKB_CB(skb)->dccpd_ack_seq, now);
-                if (r_sample == 0) {
-                        DCCP_WARN("%s(%p): %s with bogus ACK-%llu\n", dccp_role(sk), sk,
-                                  dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type),
-                                  (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq);
-                        return;
-                }
+        /* Estimate RTT from history if ACK number is valid */
+        r_sample = tfrc_tx_hist_rtt(hctx->ccid3hctx_hist,
+                                    DCCP_SKB_CB(skb)->dccpd_ack_seq, now);
+        if (r_sample == 0) {
+                DCCP_WARN("%s(%p): %s with bogus ACK-%llu\n", dccp_role(sk), sk,
+                          dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type),
+                          (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq);
+                return;
+        }
+
+        /* Update receive rate in units of 64 * bytes/second */
+        hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate;
+        hctx->ccid3hctx_x_recv <<= 6;
 
-                /* Update receive rate in units of 64 * bytes/second */
-                hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate;
-                hctx->ccid3hctx_x_recv <<= 6;
+        /* Update loss event rate (which is scaled by 1e6) */
+        pinv = opt_recv->ccid3or_loss_event_rate;
+        if (pinv == ~0U || pinv == 0)          /* see RFC 4342, 8.5   */
+                hctx->ccid3hctx_p = 0;
+        else                                   /* can not exceed 100% */
+                hctx->ccid3hctx_p = 1000000 / pinv;
+        /*
+         * Validate new RTT sample and update moving average
+         */
+        r_sample = dccp_sample_rtt(sk, r_sample);
+        hctx->ccid3hctx_rtt = tfrc_ewma(hctx->ccid3hctx_rtt, r_sample, 9);
 
-                /* Update loss event rate */
-                pinv = opt_recv->ccid3or_loss_event_rate;
-                if (pinv == ~0U || pinv == 0)          /* see RFC 4342, 8.5   */
-                        hctx->ccid3hctx_p = 0;
-                else                                   /* can not exceed 100% */
-                        hctx->ccid3hctx_p = 1000000 / pinv;
+        if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {
                 /*
-                 * Validate new RTT sample and update moving average
+                 * Larger Initial Windows [RFC 4342, sec. 5]
                  */
-                r_sample = dccp_sample_rtt(sk, r_sample);
-                hctx->ccid3hctx_rtt = tfrc_ewma(hctx->ccid3hctx_rtt, r_sample, 9);
+                hctx->ccid3hctx_x    = rfc3390_initial_rate(sk);
+                hctx->ccid3hctx_t_ld = now;
 
-                if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {
-                        /*
-                         * Larger Initial Windows [RFC 4342, sec. 5]
-                         */
-                        hctx->ccid3hctx_x    = rfc3390_initial_rate(sk);
-                        hctx->ccid3hctx_t_ld = now;
+                ccid3_update_send_interval(hctx);
 
-                        ccid3_update_send_interval(hctx);
+                ccid3_pr_debug("%s(%p), s=%u, MSS=%u, "
+                               "R_sample=%uus, X=%u\n", dccp_role(sk),
+                               sk, hctx->ccid3hctx_s,
+                               dccp_sk(sk)->dccps_mss_cache, r_sample,
+                               (unsigned)(hctx->ccid3hctx_x >> 6));
 
-                        ccid3_pr_debug("%s(%p), s=%u, MSS=%u, "
-                                       "R_sample=%uus, X=%u\n", dccp_role(sk),
-                                       sk, hctx->ccid3hctx_s,
-                                       dccp_sk(sk)->dccps_mss_cache, r_sample,
-                                       (unsigned)(hctx->ccid3hctx_x >> 6));
+                ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
+        } else {
 
-                        ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
-                } else {
+                /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
+                if (hctx->ccid3hctx_p > 0)
+                        hctx->ccid3hctx_x_calc =
+                                tfrc_calc_x(hctx->ccid3hctx_s,
+                                            hctx->ccid3hctx_rtt,
+                                            hctx->ccid3hctx_p);
+                ccid3_hc_tx_update_x(sk, &now);
 
-                        /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
-                        if (hctx->ccid3hctx_p > 0)
-                                hctx->ccid3hctx_x_calc =
-                                        tfrc_calc_x(hctx->ccid3hctx_s,
-                                                    hctx->ccid3hctx_rtt,
-                                                    hctx->ccid3hctx_p);
-                        ccid3_hc_tx_update_x(sk, &now);
-
-                        ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
-                                       "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
-                                       dccp_role(sk),
-                                       sk, hctx->ccid3hctx_rtt, r_sample,
-                                       hctx->ccid3hctx_s, hctx->ccid3hctx_p,
-                                       hctx->ccid3hctx_x_calc,
-                                       (unsigned)(hctx->ccid3hctx_x_recv >> 6),
-                                       (unsigned)(hctx->ccid3hctx_x >> 6));
-                }
+                ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
+                               "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
+                               dccp_role(sk),
+                               sk, hctx->ccid3hctx_rtt, r_sample,
+                               hctx->ccid3hctx_s, hctx->ccid3hctx_p,
+                               hctx->ccid3hctx_x_calc,
+                               (unsigned)(hctx->ccid3hctx_x_recv >> 6),
+                               (unsigned)(hctx->ccid3hctx_x >> 6));
+        }
 
-                /* unschedule no feedback timer */
-                sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
+        /* unschedule no feedback timer */
+        sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
 
-                /*
-                 * As we have calculated new ipi, delta, t_nom it is possible
-                 * that we now can send a packet, so wake up dccp_wait_for_ccid
-                 */
-                sk->sk_write_space(sk);
+        /*
+         * As we have calculated new ipi, delta, t_nom it is possible
+         * that we now can send a packet, so wake up dccp_wait_for_ccid
+         */
+        sk->sk_write_space(sk);
 
-                /*
-                 * Update timeout interval for the nofeedback timer.
-                 * We use a configuration option to increase the lower bound.
-                 * This can help avoid triggering the nofeedback timer too
-                 * often ('spinning') on LANs with small RTTs.
-                 */
-                hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt,
-                                                   CONFIG_IP_DCCP_CCID3_RTO *
-                                                   (USEC_PER_SEC/1000));
-                /*
-                 * Schedule no feedback timer to expire in
-                 * max(t_RTO, 2 * s/X)  =  max(t_RTO, 2 * t_ipi)
-                 */
-                t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
+        /*
+         * Update timeout interval for the nofeedback timer.
+         * We use a configuration option to increase the lower bound.
+         * This can help avoid triggering the nofeedback timer too
+         * often ('spinning') on LANs with small RTTs.
+         */
+        hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt,
+                                           (CONFIG_IP_DCCP_CCID3_RTO *
+                                            (USEC_PER_SEC / 1000)));
+        /*
+         * Schedule no feedback timer to expire in
+         * max(t_RTO, 2 * s/X)  =  max(t_RTO, 2 * t_ipi)
+         */
+        t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
 
-                ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
-                               "expire in %lu jiffies (%luus)\n",
-                               dccp_role(sk),
-                               sk, usecs_to_jiffies(t_nfb), t_nfb);
+        ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
+                       "expire in %lu jiffies (%luus)\n",
+                       dccp_role(sk),
+                       sk, usecs_to_jiffies(t_nfb), t_nfb);
 
-                sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
-                                   jiffies + usecs_to_jiffies(t_nfb));
-                break;
-        case TFRC_SSTATE_NO_SENT:       /* fall through */
-        case TFRC_SSTATE_TERM:          /* ignore feedback when closing */
-                break;
-        }
+        sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
+                           jiffies + usecs_to_jiffies(t_nfb));
 }
 
 static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,