From 6b5e633ab1525b4def3f36b53903b00586e9966d Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Sat, 27 Aug 2005 20:11:28 -0300 Subject: [PATCH] [CCID3]: Introduce usecs_div To avoid open coding this all over the place. Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller --- net/dccp/ccids/ccid3.c | 109 +++++++++++++++-------------------------- 1 file changed, 39 insertions(+), 70 deletions(-) diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index 60e3a5f9fc..ff41977f1e 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -40,6 +40,15 @@ #include "../packet_history.h" #include "ccid3.h" +/* + * Reason for maths with 10 here is to avoid 32 bit overflow when a is big. + */ +static inline u32 usecs_div(const u32 a, const u32 b) +{ + const u32 tmp = a * (USEC_PER_SEC / 10); + return b > 20 ? tmp / (b / 10) : tmp; +} + #ifdef CCID3_DEBUG extern int ccid3_debug; @@ -748,20 +757,13 @@ static u32 ccid3_calc_x(u16 s, u32 R, u32 p) /* Calculate new t_ipi (inter packet interval) by t_ipi = s / X_inst */ static inline void ccid3_calc_new_t_ipi(struct ccid3_hc_tx_sock *hctx) { - if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) - return; - /* if no feedback spec says t_ipi is 1 second (set elsewhere and then - * doubles after every no feedback timer (separate function) */ - - if (hctx->ccid3hctx_x < 10) { - ccid3_pr_debug("ccid3_calc_new_t_ipi - ccid3hctx_x < 10\n"); - hctx->ccid3hctx_x = 10; - } - hctx->ccid3hctx_t_ipi = (hctx->ccid3hctx_s * 100000) - / (hctx->ccid3hctx_x / 10); - /* reason for above maths with 10 in there is to avoid 32 bit - * overflow for jumbo packets */ - + /* + * If no feedback spec says t_ipi is 1 second (set elsewhere and then + * doubles after every no feedback timer (separate function) + */ + if (hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK) + hctx->ccid3hctx_t_ipi = usecs_div(hctx->ccid3hctx_s, + hctx->ccid3hctx_x); } /* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */ @@ -769,7 +771,6 @@ static inline void ccid3_calc_new_delta(struct ccid3_hc_tx_sock *hctx) { hctx->ccid3hctx_delta = min_t(u32, hctx->ccid3hctx_t_ipi / 2, TFRC_OPSYS_HALF_TIME_GRAN); - } /* @@ -802,22 +803,13 @@ static void ccid3_hc_tx_update_x(struct sock *sk) do_gettimeofday(&now); if (timeval_delta(&now, &hctx->ccid3hctx_t_ld) >= hctx->ccid3hctx_rtt) { - /* Avoid divide by zero below */ - const u32 rtt = max_t(u32, hctx->ccid3hctx_rtt, 10); - - hctx->ccid3hctx_x = max_t(u32, min_t(u32, 2 * hctx->ccid3hctx_x_recv, - 2 * hctx->ccid3hctx_x), - ((hctx->ccid3hctx_s * 100000) / - (rtt / 10))); - /* Using 100000 and 10 to avoid 32 bit overflow for jumbo frames */ + hctx->ccid3hctx_x = max_t(u32, min_t(u32, hctx->ccid3hctx_x_recv, + hctx->ccid3hctx_x) * 2, + usecs_div(hctx->ccid3hctx_s, + hctx->ccid3hctx_rtt)); hctx->ccid3hctx_t_ld = now; } } - - if (hctx->ccid3hctx_x == 0) { - ccid3_pr_debug("ccid3hctx_x = 0!\n"); - hctx->ccid3hctx_x = 1; - } } static void ccid3_hc_tx_no_feedback_timer(unsigned long data) @@ -826,7 +818,6 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) struct dccp_sock *dp = dccp_sk(sk); unsigned long next_tmout = 0; struct ccid3_hc_tx_sock *hctx = dp->dccps_hc_tx_ccid_private; - u32 rtt; bh_lock_sock(sk); if (sock_owned_by_user(sk)) { @@ -840,19 +831,14 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) ccid3_pr_debug("%s, sk=%p, state=%s\n", dccp_role(sk), sk, ccid3_tx_state_name(hctx->ccid3hctx_state)); - if (hctx->ccid3hctx_x < 10) { - ccid3_pr_debug("TFRC_SSTATE_NO_FBACK ccid3hctx_x < 10\n"); - hctx->ccid3hctx_x = 10; - } - switch (hctx->ccid3hctx_state) { case TFRC_SSTATE_TERM: goto out; case TFRC_SSTATE_NO_FBACK: /* Halve send rate */ hctx->ccid3hctx_x /= 2; - if (hctx->ccid3hctx_x < - (hctx->ccid3hctx_s / TFRC_MAX_BACK_OFF_TIME)) + if (hctx->ccid3hctx_x < (hctx->ccid3hctx_s / + TFRC_MAX_BACK_OFF_TIME)) hctx->ccid3hctx_x = (hctx->ccid3hctx_s / TFRC_MAX_BACK_OFF_TIME); @@ -861,9 +847,9 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) dccp_role(sk), sk, ccid3_tx_state_name(hctx->ccid3hctx_state), hctx->ccid3hctx_x); - next_tmout = max_t(u32, 2 * (hctx->ccid3hctx_s * 100000) / (hctx->ccid3hctx_x / 10), + next_tmout = max_t(u32, 2 * usecs_div(hctx->ccid3hctx_s, + hctx->ccid3hctx_x), TFRC_INITIAL_TIMEOUT); - /* do above maths with 100000 and 10 to prevent overflow on 32 bit */ /* * FIXME - not sure above calculation is correct. See section * 5 of CCID3 11 should adjust tx_t_ipi and double that to @@ -875,12 +861,9 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) * Check if IDLE since last timeout and recv rate is less than * 4 packets per RTT */ - rtt = hctx->ccid3hctx_rtt; - if (rtt < 10) - rtt = 10; - /* stop divide by zero below */ if (!hctx->ccid3hctx_idle || - (hctx->ccid3hctx_x_recv >= 4 * (hctx->ccid3hctx_s * 100000) / (rtt / 10))) { + (hctx->ccid3hctx_x_recv >= + 4 * usecs_div(hctx->ccid3hctx_s, hctx->ccid3hctx_rtt))) { ccid3_pr_debug("%s, sk=%p, state=%s, not idle\n", dccp_role(sk), sk, ccid3_tx_state_name(hctx->ccid3hctx_state)); @@ -905,13 +888,13 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) /* Update sending rate */ ccid3_hc_tx_update_x(sk); } - if (hctx->ccid3hctx_x == 0) { - ccid3_pr_debug("TFRC_SSTATE_FBACK ccid3hctx_x = 0!\n"); - hctx->ccid3hctx_x = 10; - } - /* Schedule no feedback timer to expire in max(4 * R, 2 * s / X) */ + /* + * Schedule no feedback timer to expire in + * max(4 * R, 2 * s / X) + */ next_tmout = max_t(u32, hctx->ccid3hctx_t_rto, - 2 * (hctx->ccid3hctx_s * 100000) / (hctx->ccid3hctx_x / 10)); + 2 * usecs_div(hctx->ccid3hctx_s, + hctx->ccid3hctx_x)); break; default: printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n", @@ -1053,8 +1036,10 @@ static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, int len) * Algorithm in "8.1. Window Counter Valuer" in * draft-ietf-dccp-ccid3-11.txt */ - quarter_rtt = timeval_delta(&now, &hctx->ccid3hctx_t_last_win_count) / - (hctx->ccid3hctx_rtt / 4); + quarter_rtt = timeval_delta(&now, &hctx->ccid3hctx_t_last_win_count); + if (likely(hctx->ccid3hctx_rtt > 8)) + quarter_rtt /= hctx->ccid3hctx_rtt / 4; + if (quarter_rtt > 0) { hctx->ccid3hctx_t_last_win_count = now; hctx->ccid3hctx_last_win_count = (hctx->ccid3hctx_last_win_count + @@ -1171,13 +1156,6 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) hctx->ccid3hctx_rtt = (hctx->ccid3hctx_rtt * 9) / 10 + r_sample / 10; - /* - * XXX: this is to avoid a division by zero in ccid3_hc_tx_packet_sent - * implemention of the new window count. - */ - if (hctx->ccid3hctx_rtt < 4) - hctx->ccid3hctx_rtt = 4; - ccid3_pr_debug("%s, sk=%p, New RTT estimate=%uus, " "r_sample=%us\n", dccp_role(sk), sk, hctx->ccid3hctx_rtt, r_sample); @@ -1220,21 +1198,14 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) dccp_tx_hist_purge_older(ccid3_tx_hist, &hctx->ccid3hctx_hist, packet); - if (hctx->ccid3hctx_x < 10) { - ccid3_pr_debug("ccid3_hc_tx_packet_recv hctx_x < 10\n"); - hctx->ccid3hctx_x = 10; - } - /* to prevent divide by zero below */ - /* * Schedule no feedback timer to expire in * max(4 * R, 2 * s / X) */ next_tmout = max(hctx->ccid3hctx_t_rto, - (2 * (hctx->ccid3hctx_s * 100000) / - (hctx->ccid3hctx_x / 10))); - /* maths with 100000 and 10 is to prevent overflow with 32 bit */ - + 2 * usecs_div(hctx->ccid3hctx_s, + hctx->ccid3hctx_x)); + ccid3_pr_debug("%s, sk=%p, Scheduled no feedback timer to " "expire in %lu jiffies (%luus)\n", dccp_role(sk), sk, @@ -1350,8 +1321,6 @@ static int ccid3_hc_tx_init(struct sock *sk) /* Set transmission rate to 1 packet per second */ hctx->ccid3hctx_x = hctx->ccid3hctx_s; - /* See ccid3_hc_tx_packet_sent win_count calculatation */ - hctx->ccid3hctx_rtt = 4; hctx->ccid3hctx_t_rto = USEC_PER_SEC; hctx->ccid3hctx_state = TFRC_SSTATE_NO_SENT; INIT_LIST_HEAD(&hctx->ccid3hctx_hist); -- 2.39.5