[DCCP] ccid3: Fix two bugs in sending rate computation

[pandora-kernel.git] / net / dccp / ccids / ccid3.c

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 66a27b9..c54663f 100644 (file)
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -138,9 +138,6 @@ static void ccid3_hc_tx_update_x(struct sock *sk, struct timeval *now)
        const __u32 old_x = hctx->ccid3hctx_x;
 
        if (hctx->ccid3hctx_p > 0) {
-               hctx->ccid3hctx_x_calc = tfrc_calc_x(hctx->ccid3hctx_s,
-                                                    hctx->ccid3hctx_rtt,
-                                                    hctx->ccid3hctx_p);
                hctx->ccid3hctx_x = max_t(u32, min(hctx->ccid3hctx_x_calc,
                                                   hctx->ccid3hctx_x_recv * 2),
                                               hctx->ccid3hctx_s / TFRC_T_MBI);
@@ -152,8 +149,7 @@ static void ccid3_hc_tx_update_x(struct sock *sk, struct timeval *now)
                                        usecs_div(hctx->ccid3hctx_s,
                                                  hctx->ccid3hctx_rtt)   );
                hctx->ccid3hctx_t_ld = *now;
-       } else
-               ccid3_pr_debug("Not changing X\n");
+       }
 
        if (hctx->ccid3hctx_x != old_x)
                ccid3_update_send_time(hctx);
@@ -197,7 +193,7 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
        switch (hctx->ccid3hctx_state) {
        case TFRC_SSTATE_NO_FBACK:
                /* RFC 3448, 4.4: Halve send rate directly */
-               hctx->ccid3hctx_x = min_t(u32, hctx->ccid3hctx_x / 2,
+               hctx->ccid3hctx_x = max_t(u32, hctx->ccid3hctx_x / 2,
                                               hctx->ccid3hctx_s / TFRC_T_MBI);
 
                ccid3_pr_debug("%s, sk=%p, state=%s, updated tx rate to %d "
@@ -223,9 +219,11 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
                        ccid3_pr_debug("%s, sk=%p, state=%s, not idle\n",
                                       dccp_role(sk), sk,
                                       ccid3_tx_state_name(hctx->ccid3hctx_state));
-                       /* Halve sending rate */
 
-                       /*  If (p == 0 || X_calc > 2 * X_recv)
+                       /*
+                        *  Modify the cached value of X_recv [RFC 3448, 4.4]
+                        *
+                        *  If (p == 0 || X_calc > 2 * X_recv)
                         *    X_recv = max(X_recv / 2, s / (2 * t_mbi));
                         *  Else
                         *    X_recv = X_calc / 4;
@@ -233,14 +231,15 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
                        BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc);
 
                        if (hctx->ccid3hctx_p  == 0 ||
-                           hctx->ccid3hctx_x_calc > 2 * hctx->ccid3hctx_x_recv)
+                           hctx->ccid3hctx_x_calc > 2 * hctx->ccid3hctx_x_recv)  {
                                hctx->ccid3hctx_x_recv = max_t(u32, hctx->ccid3hctx_x_recv / 2,
                                                                    hctx->ccid3hctx_s / (2 * TFRC_T_MBI));
-                       else
+                               if (hctx->ccid3hctx_p == 0)
+                                       dccp_timestamp(sk, &now);
+                       } else
                                hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc / 4;
 
-                       /* Update sending rate */
-                       dccp_timestamp(sk, &now);
+                       /* Now recalculate X [RFC 3448, 4.3, step (4)] */
                        ccid3_hc_tx_update_x(sk, &now);
                }
                /*
@@ -444,9 +443,9 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 
                /* Update loss event rate */
                pinv = opt_recv->ccid3or_loss_event_rate;
-               if (pinv == ~0U || pinv == 0)
+               if (pinv == ~0U || pinv == 0)          /* see RFC 4342, 8.5   */
                        hctx->ccid3hctx_p = 0;
-               else
+               else                                   /* can not exceed 100% */
                        hctx->ccid3hctx_p = 1000000 / pinv;
 
                dccp_timestamp(sk, &now);
@@ -478,7 +477,7 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
                if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {
                        /* Use Larger Initial Windows [RFC 4342, sec. 5]
                         * We deviate in that we use `s' instead of `MSS'. */
-                       u16 w_init = max(    4 * hctx->ccid3hctx_s,
+                       u16 w_init = min(    4 * hctx->ccid3hctx_s,
                                         max(2 * hctx->ccid3hctx_s, 4380));
                        hctx->ccid3hctx_rtt  = r_sample;
                        hctx->ccid3hctx_x    = usecs_div(w_init, r_sample);
@@ -496,6 +495,12 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
                        hctx->ccid3hctx_rtt = (9 * hctx->ccid3hctx_rtt +
                                                   (u32)r_sample        ) / 10;
 
+                       /* 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=%ldus), s=%u, "
@@ -733,10 +738,15 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk)
        /* Convert to multiples of 10us */
        hcrx->ccid3hcrx_elapsed_time =
                        timeval_delta(&now, &packet->dccphrx_tstamp) / 10;
+
        if (hcrx->ccid3hcrx_p == 0)
-               hcrx->ccid3hcrx_pinv = ~0;
-       else
+               hcrx->ccid3hcrx_pinv = ~0U;     /* see RFC 4342, 8.5 */
+       else if (hcrx->ccid3hcrx_p > 1000000) {
+               DCCP_WARN("p (%u) > 100%%\n", hcrx->ccid3hcrx_p);
+               hcrx->ccid3hcrx_pinv = 1;       /* use 100% in this case */
+       } else
                hcrx->ccid3hcrx_pinv = 1000000 / hcrx->ccid3hcrx_p;
+
        dp->dccps_hc_rx_insert_options = 1;
        dccp_send_ack(sk);
 }