[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>

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index e31560daa0b94653404b7788468936975da43411..a93a556ad03dafd6b7df55b05c4639110a635def 100644 (file)
--- 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,