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path: root/net/dccp/ccids/ccid3.c
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Diffstat (limited to 'net/dccp/ccids/ccid3.c')
-rw-r--r--net/dccp/ccids/ccid3.c27
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);