Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   1) // SPDX-License-Identifier: GPL-2.0-only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   3)  * CAIA Delay-Gradient (CDG) congestion control
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   4)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   5)  * This implementation is based on the paper:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   6)  *   D.A. Hayes and G. Armitage. "Revisiting TCP congestion control using
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   7)  *   delay gradients." In IFIP Networking, pages 328-341. Springer, 2011.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   8)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   9)  * Scavenger traffic (Less-than-Best-Effort) should disable coexistence
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  10)  * heuristics using parameters use_shadow=0 and use_ineff=0.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  11)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  12)  * Parameters window, backoff_beta, and backoff_factor are crucial for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  13)  * throughput and delay. Future work is needed to determine better defaults,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  14)  * and to provide guidelines for use in different environments/contexts.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  15)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  16)  * Except for window, knobs are configured via /sys/module/tcp_cdg/parameters/.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  17)  * Parameter window is only configurable when loading tcp_cdg as a module.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  18)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  19)  * Notable differences from paper/FreeBSD:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  20)  *   o Using Hybrid Slow start and Proportional Rate Reduction.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  21)  *   o Add toggle for shadow window mechanism. Suggested by David Hayes.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  22)  *   o Add toggle for non-congestion loss tolerance.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  23)  *   o Scaling parameter G is changed to a backoff factor;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  24)  *     conversion is given by: backoff_factor = 1000/(G * window).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  25)  *   o Limit shadow window to 2 * cwnd, or to cwnd when application limited.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  26)  *   o More accurate e^-x.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  27)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  28) #include <linux/kernel.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  29) #include <linux/random.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  30) #include <linux/module.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  31) #include <linux/sched/clock.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  32) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  33) #include <net/tcp.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  34) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  35) #define HYSTART_ACK_TRAIN	1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  36) #define HYSTART_DELAY		2
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  37) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  38) static int window __read_mostly = 8;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  39) static unsigned int backoff_beta __read_mostly = 0.7071 * 1024; /* sqrt 0.5 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  40) static unsigned int backoff_factor __read_mostly = 42;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  41) static unsigned int hystart_detect __read_mostly = 3;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  42) static unsigned int use_ineff __read_mostly = 5;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  43) static bool use_shadow __read_mostly = true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  44) static bool use_tolerance __read_mostly;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  45) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  46) module_param(window, int, 0444);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  47) MODULE_PARM_DESC(window, "gradient window size (power of two <= 256)");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  48) module_param(backoff_beta, uint, 0644);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  49) MODULE_PARM_DESC(backoff_beta, "backoff beta (0-1024)");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  50) module_param(backoff_factor, uint, 0644);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  51) MODULE_PARM_DESC(backoff_factor, "backoff probability scale factor");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  52) module_param(hystart_detect, uint, 0644);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  53) MODULE_PARM_DESC(hystart_detect, "use Hybrid Slow start "
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  54) 		 "(0: disabled, 1: ACK train, 2: delay threshold, 3: both)");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  55) module_param(use_ineff, uint, 0644);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  56) MODULE_PARM_DESC(use_ineff, "use ineffectual backoff detection (threshold)");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  57) module_param(use_shadow, bool, 0644);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  58) MODULE_PARM_DESC(use_shadow, "use shadow window heuristic");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  59) module_param(use_tolerance, bool, 0644);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  60) MODULE_PARM_DESC(use_tolerance, "use loss tolerance heuristic");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  61) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  62) struct cdg_minmax {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  63) 	union {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  64) 		struct {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  65) 			s32 min;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  66) 			s32 max;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  67) 		};
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  68) 		u64 v64;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  69) 	};
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  70) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  71) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  72) enum cdg_state {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  73) 	CDG_UNKNOWN = 0,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  74) 	CDG_NONFULL = 1,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  75) 	CDG_FULL    = 2,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  76) 	CDG_BACKOFF = 3,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  77) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  78) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  79) struct cdg {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  80) 	struct cdg_minmax rtt;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  81) 	struct cdg_minmax rtt_prev;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  82) 	struct cdg_minmax *gradients;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  83) 	struct cdg_minmax gsum;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  84) 	bool gfilled;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  85) 	u8  tail;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  86) 	u8  state;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  87) 	u8  delack;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  88) 	u32 rtt_seq;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  89) 	u32 shadow_wnd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  90) 	u16 backoff_cnt;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  91) 	u16 sample_cnt;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  92) 	s32 delay_min;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  93) 	u32 last_ack;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  94) 	u32 round_start;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  95) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  96) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  97) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  98)  * nexp_u32 - negative base-e exponential
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  99)  * @ux: x in units of micro
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101)  * Returns exp(ux * -1e-6) * U32_MAX.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) static u32 __pure nexp_u32(u32 ux)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) 	static const u16 v[] = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) 		/* exp(-x)*65536-1 for x = 0, 0.000256, 0.000512, ... */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) 		65535,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) 		65518, 65501, 65468, 65401, 65267, 65001, 64470, 63422,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) 		61378, 57484, 50423, 38795, 22965, 8047,  987,   14,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) 	};
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) 	u32 msb = ux >> 8;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) 	u32 res;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) 	int i;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) 	/* Cut off when ux >= 2^24 (actual result is <= 222/U32_MAX). */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) 	if (msb > U16_MAX)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) 		return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) 	/* Scale first eight bits linearly: */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) 	res = U32_MAX - (ux & 0xff) * (U32_MAX / 1000000);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) 	/* Obtain e^(x + y + ...) by computing e^x * e^y * ...: */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) 	for (i = 1; msb; i++, msb >>= 1) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) 		u32 y = v[i & -(msb & 1)] + U32_C(1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) 		res = ((u64)res * y) >> 16;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) 	return res;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) /* Based on the HyStart algorithm (by Ha et al.) that is implemented in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133)  * tcp_cubic. Differences/experimental changes:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134)  *   o Using Hayes' delayed ACK filter.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135)  *   o Using a usec clock for the ACK train.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136)  *   o Reset ACK train when application limited.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137)  *   o Invoked at any cwnd (i.e. also when cwnd < 16).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138)  *   o Invoked only when cwnd < ssthresh (i.e. not when cwnd == ssthresh).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) static void tcp_cdg_hystart_update(struct sock *sk)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) 	struct cdg *ca = inet_csk_ca(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) 	struct tcp_sock *tp = tcp_sk(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) 	ca->delay_min = min_not_zero(ca->delay_min, ca->rtt.min);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) 	if (ca->delay_min == 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) 	if (hystart_detect & HYSTART_ACK_TRAIN) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) 		u32 now_us = tp->tcp_mstamp;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) 		if (ca->last_ack == 0 || !tcp_is_cwnd_limited(sk)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) 			ca->last_ack = now_us;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) 			ca->round_start = now_us;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) 		} else if (before(now_us, ca->last_ack + 3000)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) 			u32 base_owd = max(ca->delay_min / 2U, 125U);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) 			ca->last_ack = now_us;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) 			if (after(now_us, ca->round_start + base_owd)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) 				NET_INC_STATS(sock_net(sk),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) 					      LINUX_MIB_TCPHYSTARTTRAINDETECT);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) 				NET_ADD_STATS(sock_net(sk),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) 					      LINUX_MIB_TCPHYSTARTTRAINCWND,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) 					      tp->snd_cwnd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) 				tp->snd_ssthresh = tp->snd_cwnd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) 				return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) 			}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) 	if (hystart_detect & HYSTART_DELAY) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) 		if (ca->sample_cnt < 8) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) 			ca->sample_cnt++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) 		} else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) 			s32 thresh = max(ca->delay_min + ca->delay_min / 8U,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) 					 125U);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) 			if (ca->rtt.min > thresh) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) 				NET_INC_STATS(sock_net(sk),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) 					      LINUX_MIB_TCPHYSTARTDELAYDETECT);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) 				NET_ADD_STATS(sock_net(sk),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) 					      LINUX_MIB_TCPHYSTARTDELAYCWND,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) 					      tp->snd_cwnd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) 				tp->snd_ssthresh = tp->snd_cwnd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) 			}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) static s32 tcp_cdg_grad(struct cdg *ca)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) 	s32 gmin = ca->rtt.min - ca->rtt_prev.min;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) 	s32 gmax = ca->rtt.max - ca->rtt_prev.max;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) 	s32 grad;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) 	if (ca->gradients) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) 		ca->gsum.min += gmin - ca->gradients[ca->tail].min;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) 		ca->gsum.max += gmax - ca->gradients[ca->tail].max;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) 		ca->gradients[ca->tail].min = gmin;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) 		ca->gradients[ca->tail].max = gmax;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) 		ca->tail = (ca->tail + 1) & (window - 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) 		gmin = ca->gsum.min;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) 		gmax = ca->gsum.max;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) 	/* We keep sums to ignore gradients during cwnd reductions;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) 	 * the paper's smoothed gradients otherwise simplify to:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) 	 * (rtt_latest - rtt_oldest) / window.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) 	 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) 	 * We also drop division by window here.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) 	grad = gmin > 0 ? gmin : gmax;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) 	/* Extrapolate missing values in gradient window: */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) 	if (!ca->gfilled) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) 		if (!ca->gradients && window > 1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217) 			grad *= window; /* Memory allocation failed. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) 		else if (ca->tail == 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) 			ca->gfilled = true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) 		else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221) 			grad = (grad * window) / (int)ca->tail;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) 	/* Backoff was effectual: */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) 	if (gmin <= -32 || gmax <= -32)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) 		ca->backoff_cnt = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) 	if (use_tolerance) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) 		/* Reduce small variations to zero: */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) 		gmin = DIV_ROUND_CLOSEST(gmin, 64);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) 		gmax = DIV_ROUND_CLOSEST(gmax, 64);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) 		if (gmin > 0 && gmax <= 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) 			ca->state = CDG_FULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) 		else if ((gmin > 0 && gmax > 0) || gmax < 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) 			ca->state = CDG_NONFULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) 	return grad;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) static bool tcp_cdg_backoff(struct sock *sk, u32 grad)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) 	struct cdg *ca = inet_csk_ca(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) 	struct tcp_sock *tp = tcp_sk(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) 	if (prandom_u32() <= nexp_u32(grad * backoff_factor))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) 		return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) 	if (use_ineff) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) 		ca->backoff_cnt++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251) 		if (ca->backoff_cnt > use_ineff)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252) 			return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255) 	ca->shadow_wnd = max(ca->shadow_wnd, tp->snd_cwnd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256) 	ca->state = CDG_BACKOFF;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257) 	tcp_enter_cwr(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258) 	return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261) /* Not called in CWR or Recovery state. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) static void tcp_cdg_cong_avoid(struct sock *sk, u32 ack, u32 acked)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 263) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 264) 	struct cdg *ca = inet_csk_ca(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 265) 	struct tcp_sock *tp = tcp_sk(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 266) 	u32 prior_snd_cwnd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 267) 	u32 incr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 268) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 269) 	if (tcp_in_slow_start(tp) && hystart_detect)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 270) 		tcp_cdg_hystart_update(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 271) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 272) 	if (after(ack, ca->rtt_seq) && ca->rtt.v64) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 273) 		s32 grad = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 274) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 275) 		if (ca->rtt_prev.v64)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 276) 			grad = tcp_cdg_grad(ca);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 277) 		ca->rtt_seq = tp->snd_nxt;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 278) 		ca->rtt_prev = ca->rtt;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 279) 		ca->rtt.v64 = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 280) 		ca->last_ack = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 281) 		ca->sample_cnt = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 282) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 283) 		if (grad > 0 && tcp_cdg_backoff(sk, grad))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 284) 			return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 285) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 286) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 287) 	if (!tcp_is_cwnd_limited(sk)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 288) 		ca->shadow_wnd = min(ca->shadow_wnd, tp->snd_cwnd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 289) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 290) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 291) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 292) 	prior_snd_cwnd = tp->snd_cwnd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 293) 	tcp_reno_cong_avoid(sk, ack, acked);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 294) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 295) 	incr = tp->snd_cwnd - prior_snd_cwnd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 296) 	ca->shadow_wnd = max(ca->shadow_wnd, ca->shadow_wnd + incr);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 297) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 298) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 299) static void tcp_cdg_acked(struct sock *sk, const struct ack_sample *sample)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 300) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 301) 	struct cdg *ca = inet_csk_ca(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 302) 	struct tcp_sock *tp = tcp_sk(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 303) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 304) 	if (sample->rtt_us <= 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 305) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 306) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 307) 	/* A heuristic for filtering delayed ACKs, adapted from:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 308) 	 * D.A. Hayes. "Timing enhancements to the FreeBSD kernel to support
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 309) 	 * delay and rate based TCP mechanisms." TR 100219A. CAIA, 2010.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 310) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 311) 	if (tp->sacked_out == 0) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 312) 		if (sample->pkts_acked == 1 && ca->delack) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 313) 			/* A delayed ACK is only used for the minimum if it is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 314) 			 * provenly lower than an existing non-zero minimum.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 315) 			 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 316) 			ca->rtt.min = min(ca->rtt.min, sample->rtt_us);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 317) 			ca->delack--;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 318) 			return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 319) 		} else if (sample->pkts_acked > 1 && ca->delack < 5) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 320) 			ca->delack++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 321) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 322) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 323) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 324) 	ca->rtt.min = min_not_zero(ca->rtt.min, sample->rtt_us);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 325) 	ca->rtt.max = max(ca->rtt.max, sample->rtt_us);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 326) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 327) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 328) static u32 tcp_cdg_ssthresh(struct sock *sk)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 329) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 330) 	struct cdg *ca = inet_csk_ca(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 331) 	struct tcp_sock *tp = tcp_sk(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 332) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 333) 	if (ca->state == CDG_BACKOFF)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 334) 		return max(2U, (tp->snd_cwnd * min(1024U, backoff_beta)) >> 10);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 335) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 336) 	if (ca->state == CDG_NONFULL && use_tolerance)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 337) 		return tp->snd_cwnd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 338) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 339) 	ca->shadow_wnd = min(ca->shadow_wnd >> 1, tp->snd_cwnd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 340) 	if (use_shadow)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 341) 		return max3(2U, ca->shadow_wnd, tp->snd_cwnd >> 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 342) 	return max(2U, tp->snd_cwnd >> 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 343) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 344) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 345) static void tcp_cdg_cwnd_event(struct sock *sk, const enum tcp_ca_event ev)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 346) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 347) 	struct cdg *ca = inet_csk_ca(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 348) 	struct tcp_sock *tp = tcp_sk(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 349) 	struct cdg_minmax *gradients;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 350) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 351) 	switch (ev) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 352) 	case CA_EVENT_CWND_RESTART:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 353) 		gradients = ca->gradients;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 354) 		if (gradients)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 355) 			memset(gradients, 0, window * sizeof(gradients[0]));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 356) 		memset(ca, 0, sizeof(*ca));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 357) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 358) 		ca->gradients = gradients;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 359) 		ca->rtt_seq = tp->snd_nxt;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 360) 		ca->shadow_wnd = tp->snd_cwnd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 361) 		break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 362) 	case CA_EVENT_COMPLETE_CWR:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 363) 		ca->state = CDG_UNKNOWN;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 364) 		ca->rtt_seq = tp->snd_nxt;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 365) 		ca->rtt_prev = ca->rtt;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 366) 		ca->rtt.v64 = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 367) 		break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 368) 	default:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 369) 		break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 370) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 371) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 372) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 373) static void tcp_cdg_init(struct sock *sk)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 374) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 375) 	struct cdg *ca = inet_csk_ca(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 376) 	struct tcp_sock *tp = tcp_sk(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 377) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 378) 	/* We silently fall back to window = 1 if allocation fails. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 379) 	if (window > 1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 380) 		ca->gradients = kcalloc(window, sizeof(ca->gradients[0]),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 381) 					GFP_NOWAIT | __GFP_NOWARN);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 382) 	ca->rtt_seq = tp->snd_nxt;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 383) 	ca->shadow_wnd = tp->snd_cwnd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 384) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 385) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 386) static void tcp_cdg_release(struct sock *sk)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 387) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 388) 	struct cdg *ca = inet_csk_ca(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 389) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 390) 	kfree(ca->gradients);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 391) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 392) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 393) static struct tcp_congestion_ops tcp_cdg __read_mostly = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 394) 	.cong_avoid = tcp_cdg_cong_avoid,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 395) 	.cwnd_event = tcp_cdg_cwnd_event,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 396) 	.pkts_acked = tcp_cdg_acked,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 397) 	.undo_cwnd = tcp_reno_undo_cwnd,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 398) 	.ssthresh = tcp_cdg_ssthresh,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 399) 	.release = tcp_cdg_release,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 400) 	.init = tcp_cdg_init,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 401) 	.owner = THIS_MODULE,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 402) 	.name = "cdg",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 403) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 404) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 405) static int __init tcp_cdg_register(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 406) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 407) 	if (backoff_beta > 1024 || window < 1 || window > 256)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 408) 		return -ERANGE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 409) 	if (!is_power_of_2(window))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 410) 		return -EINVAL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 411) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 412) 	BUILD_BUG_ON(sizeof(struct cdg) > ICSK_CA_PRIV_SIZE);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 413) 	tcp_register_congestion_control(&tcp_cdg);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 414) 	return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 415) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 416) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 417) static void __exit tcp_cdg_unregister(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 418) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 419) 	tcp_unregister_congestion_control(&tcp_cdg);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 420) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 421) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 422) module_init(tcp_cdg_register);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 423) module_exit(tcp_cdg_unregister);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 424) MODULE_AUTHOR("Kenneth Klette Jonassen");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 425) MODULE_LICENSE("GPL");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 426) MODULE_DESCRIPTION("TCP CDG");