TCP CCAs in Rust

net/ipv4/Kconfig

@@ -466,6 +466,22 @@ config INET_DIAG_DESTROY
 	  had been disconnected.
 	  If unsure, say N.
 
+config RUST_SOCK_ABSTRACTIONS
+	bool "INET: Rust sock abstractions"
+	depends on RUST
+	help
+	  Adds Rust abstractions for working with `struct sock`s.
+
+	  If unsure, say N.
+
+config RUST_TCP_ABSTRACTIONS
+	bool "TCP: Rust abstractions"
+	depends on RUST_SOCK_ABSTRACTIONS
+	help
+	  Adds support for writing Rust kernel modules that integrate with TCP.
+
+	  If unsure, say N.
+
 menuconfig TCP_CONG_ADVANCED
 	bool "TCP: advanced congestion control"
 	help
@@ -493,6 +509,15 @@ config TCP_CONG_BIC
 	  increase provides TCP friendliness.
 	  See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
 
+config TCP_CONG_BIC_RUST
+	tristate "Binary Increase Congestion (BIC) control (Rust rewrite)"
+	depends on RUST_TCP_ABSTRACTIONS
+	help
+	  Rust rewrite of the original implementation of Binary Increase
+	  Congestion (BIC) control.
+
+	  If unsure, say N.
+
 config TCP_CONG_CUBIC
 	tristate "CUBIC TCP"
 	default y
@@ -501,6 +526,15 @@ config TCP_CONG_CUBIC
 	  among other techniques.
 	  See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf
 
+config TCP_CONG_CUBIC_RUST
+	tristate "CUBIC TCP (Rust rewrite)"
+	depends on RUST_TCP_ABSTRACTIONS
+	help
+	  Rust rewrite of the original implementation of TCP CUBIC congestion
+	  control.
+
+	  If unsure, say N.
+
 config TCP_CONG_WESTWOOD
 	tristate "TCP Westwood+"
 	default m
@@ -688,9 +722,15 @@ choice
 	config DEFAULT_BIC
 		bool "Bic" if TCP_CONG_BIC=y
 
+	config DEFAULT_BIC_RUST
+		bool "Bic (Rust)" if TCP_CONG_BIC_RUST=y
+
 	config DEFAULT_CUBIC
 		bool "Cubic" if TCP_CONG_CUBIC=y
 
+	config DEFAULT_CUBIC_RUST
+		bool "Cubic (Rust)" if TCP_CONG_CUBIC_RUST=y
+
 	config DEFAULT_HTCP
 		bool "Htcp" if TCP_CONG_HTCP=y
 
@@ -729,7 +769,9 @@ config TCP_CONG_CUBIC
 config DEFAULT_TCP_CONG
 	string
 	default "bic" if DEFAULT_BIC
+	default "bic_rust" if DEFAULT_BIC_RUST
 	default "cubic" if DEFAULT_CUBIC
+	default "cubic_rust" if DEFAULT_CUBIC_RUST
 	default "htcp" if DEFAULT_HTCP
 	default "hybla" if DEFAULT_HYBLA
 	default "vegas" if DEFAULT_VEGAS

net/ipv4/Makefile

@@ -46,8 +46,10 @@ obj-$(CONFIG_INET_UDP_DIAG) += udp_diag.o
 obj-$(CONFIG_INET_RAW_DIAG) += raw_diag.o
 obj-$(CONFIG_TCP_CONG_BBR) += tcp_bbr.o
 obj-$(CONFIG_TCP_CONG_BIC) += tcp_bic.o
+obj-$(CONFIG_TCP_CONG_BIC_RUST) += tcp_bic_rust.o
 obj-$(CONFIG_TCP_CONG_CDG) += tcp_cdg.o
 obj-$(CONFIG_TCP_CONG_CUBIC) += tcp_cubic.o
+obj-$(CONFIG_TCP_CONG_CUBIC_RUST) += tcp_cubic_rust.o
 obj-$(CONFIG_TCP_CONG_DCTCP) += tcp_dctcp.o
 obj-$(CONFIG_TCP_CONG_WESTWOOD) += tcp_westwood.o
 obj-$(CONFIG_TCP_CONG_HSTCP) += tcp_highspeed.o

net/ipv4/tcp_bic.c

@@ -16,6 +16,7 @@
 
 #include <linux/mm.h>
 #include <linux/module.h>
+#include <linux/time.h>
 #include <net/tcp.h>
 
 #define BICTCP_BETA_SCALE    1024	/* Scale factor beta calculation
@@ -55,6 +56,7 @@ struct bictcp {
 	u32	epoch_start;	/* beginning of an epoch */
 #define ACK_RATIO_SHIFT	4
 	u32	delayed_ack;	/* estimate the ratio of Packets/ACKs << 4 */
+	u64	start_time;
 };
 
 static inline void bictcp_reset(struct bictcp *ca)
@@ -65,6 +67,7 @@ static inline void bictcp_reset(struct bictcp *ca)
 	ca->last_time = 0;
 	ca->epoch_start = 0;
 	ca->delayed_ack = 2 << ACK_RATIO_SHIFT;
+	ca->start_time = ktime_get_boot_fast_ns();
 }
 
 static void bictcp_init(struct sock *sk)
@@ -75,6 +78,19 @@ static void bictcp_init(struct sock *sk)
 
 	if (initial_ssthresh)
 		tcp_sk(sk)->snd_ssthresh = initial_ssthresh;
+
+	pr_info("Socket created: start %llu\n", ca->start_time);
+}
+
+static void bictcp_release(struct sock* sk)
+{
+	struct bictcp *ca = inet_csk_ca(sk);
+
+        pr_info(
+		"Socket destroyed: start %llu, end %llu\n",
+		ca->start_time,
+		ktime_get_boot_fast_ns()
+        );
 }
 
 /*
@@ -147,11 +163,23 @@ static void bictcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
 
 	if (tcp_in_slow_start(tp)) {
 		acked = tcp_slow_start(tp, acked);
-		if (!acked)
+		if (!acked) {
+			pr_info(
+				"New cwnd: %u, time %llu, ssthresh %u, start %llu, ss 1\n",
+				tp->snd_cwnd, ktime_get_boot_fast_ns(),
+				tp->snd_ssthresh, ca->start_time
+			);
 			return;
+		}
 	}
 	bictcp_update(ca, tcp_snd_cwnd(tp));
 	tcp_cong_avoid_ai(tp, ca->cnt, acked);
+
+	pr_info(
+		"New cwnd: %u, time %llu, ssthresh %u, start %llu, ss 1\n",
+		tp->snd_cwnd, ktime_get_boot_fast_ns(),
+		tp->snd_ssthresh, ca->start_time
+	);
 }
 
 /*
@@ -163,6 +191,12 @@ static u32 bictcp_recalc_ssthresh(struct sock *sk)
 	const struct tcp_sock *tp = tcp_sk(sk);
 	struct bictcp *ca = inet_csk_ca(sk);
 
+        pr_info(
+		"Enter fast retransmit: time %llu, start %llu\n",
+		ktime_get_boot_fast_ns(),
+		ca->start_time
+	);
+
 	ca->epoch_start = 0;	/* end of epoch */
 
 	/* Wmax and fast convergence */
@@ -180,8 +214,20 @@ static u32 bictcp_recalc_ssthresh(struct sock *sk)
 
 static void bictcp_state(struct sock *sk, u8 new_state)
 {
-	if (new_state == TCP_CA_Loss)
+	if (new_state == TCP_CA_Loss) {
+		struct bictcp *ca = inet_csk_ca(sk);
+		u64 tmp = ca->start_time;
+
+		pr_info(
+			"Retransmission timeout fired: time %llu, start %llu\n",
+			ktime_get_boot_fast_ns(),
+			ca->start_time
+		);
+
 		bictcp_reset(inet_csk_ca(sk));
+
+		ca->start_time = tmp;
+	}
 }
 
 /* Track delayed acknowledgment ratio using sliding window
@@ -201,6 +247,7 @@ static void bictcp_acked(struct sock *sk, const struct ack_sample *sample)
 
 static struct tcp_congestion_ops bictcp __read_mostly = {
 	.init		= bictcp_init,
+	.release	= bictcp_release,
 	.ssthresh	= bictcp_recalc_ssthresh,
 	.cong_avoid	= bictcp_cong_avoid,
 	.set_state	= bictcp_state,