[CCID3]: Introduce usecs_div (6b5e633a) · Commits · e / devices / android_kernel_fairphone_FP5

net/dccp/ccids/ccid3.c

+39 −70

Original line number	Diff line number	Diff line
		@@ -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);
		@@ -1220,20 +1198,13 @@ 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",
		@@ -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);