1 files changed, 14 insertions, 13 deletions

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index cd61dea2eea1..a1929f33d703 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -159,8 +159,8 @@ static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp)
         } else if (ktime_us_delta(now, hctx->ccid3hctx_t_ld)
                                 - (s64)hctx->ccid3hctx_rtt >= 0) {
 
-                hctx->ccid3hctx_x =
-                        max(min(2 * hctx->ccid3hctx_x, min_rate),
+                hctx->ccid3hctx_x = min(2 * hctx->ccid3hctx_x, min_rate);
+                hctx->ccid3hctx_x = max(hctx->ccid3hctx_x,
                             scaled_div(((__u64)hctx->ccid3hctx_s) << 6,
                                        hctx->ccid3hctx_rtt));
                 hctx->ccid3hctx_t_ld = now;
@@ -193,22 +193,17 @@ static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hctx, int len)
 
 /*
  *      Update Window Counter using the algorithm from [RFC 4342, 8.1].
- *      The algorithm is not applicable if RTT < 4 microseconds.
+ *      As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt().
  */
 static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx,
                                                 ktime_t now)
 {
-        u32 quarter_rtts;
-
-        if (unlikely(hctx->ccid3hctx_rtt < 4))  /* avoid divide-by-zero */
-                return;
-
-        quarter_rtts = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count);
-        quarter_rtts /= hctx->ccid3hctx_rtt / 4;
+        u32 delta = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count),
+            quarter_rtts = (4 * delta) / hctx->ccid3hctx_rtt;
 
         if (quarter_rtts > 0) {
                 hctx->ccid3hctx_t_last_win_count = now;
-                hctx->ccid3hctx_last_win_count  += min_t(u32, quarter_rtts, 5);
+                hctx->ccid3hctx_last_win_count  += min(quarter_rtts, 5U);
                 hctx->ccid3hctx_last_win_count  &= 0xF;         /* mod 16 */
         }
 }
@@ -334,8 +329,14 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
                         hctx->ccid3hctx_x    = rfc3390_initial_rate(sk);
                         hctx->ccid3hctx_t_ld = now;
                 } else {
-                        /* Sender does not have RTT sample: X_pps = 1 pkt/sec */
-                        hctx->ccid3hctx_x = hctx->ccid3hctx_s;
+                        /*
+                         * Sender does not have RTT sample:
+                         * - set fallback RTT (RFC 4340, 3.4) since a RTT value
+                         *   is needed in several parts (e.g.  window counter);
+                         * - set sending rate X_pps = 1pps as per RFC 3448, 4.2.
+                         */
+                        hctx->ccid3hctx_rtt = DCCP_FALLBACK_RTT;
+                        hctx->ccid3hctx_x   = hctx->ccid3hctx_s;
                         hctx->ccid3hctx_x <<= 6;
                 }
                 ccid3_update_send_interval(hctx);