0001-ss-output-TCP-BBRv3-diag-information.patch

From ca7f11ebc4d4a99ccfd44be8555d505b26996c12 Mon Sep 17 00:00:00 2001
From: Arjun Roy <arjunroy@google.com>
Date: Mon, 25 Jul 2022 12:49:35 -0400
Subject: [PATCH 2/2] ss: output TCP BBRv3 diag information

Add logic for printing diag information for TCP BBRv3 congestion
control.  This commit leaves in place the support for printing the
earlier TCP BBRv1 congestion control information.

Both BBRv1 and BBRv3 are using the same enum value.  The BBRv3 struct
starts with the same data as BBRv1, so it is is backward-compatible
with BBRv1, to allow lder ss binaries to print basic information for
BBRv3. We use the size of the returned data and the version field to
check the version of the data.

Signed-off-by: Arjun Roy <arjunroy@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David Morley <morleyd@google.com>
---
 include/uapi/linux/inet_diag.h | 23 ++++++++++++
 misc/ss.c                      | 66 +++++++++++++++++++++++++++++++++-
 2 files changed, 88 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
index d81cb69a26a9..dca833ecb783 100644
--- a/include/uapi/linux/inet_diag.h
+++ b/include/uapi/linux/inet_diag.h
@@ -229,6 +229,29 @@ struct tcp_bbr_info {
 	__u32	bbr_min_rtt;		/* min-filtered RTT in uSec */
 	__u32	bbr_pacing_gain;	/* pacing gain shifted left 8 bits */
 	__u32	bbr_cwnd_gain;		/* cwnd gain shifted left 8 bits */
+	__u32	bbr_bw_hi_lsb;		/* lower 32 bits of bw_hi */
+	__u32	bbr_bw_hi_msb;		/* upper 32 bits of bw_hi */
+	__u32	bbr_bw_lo_lsb;		/* lower 32 bits of bw_lo */
+	__u32	bbr_bw_lo_msb;		/* upper 32 bits of bw_lo */
+	__u8	bbr_mode;		/* current bbr_mode in state machine */
+	__u8	bbr_phase;		/* current state machine phase */
+	__u8	unused1;		/* alignment padding; not used yet */
+	__u8	bbr_version;		/* BBR algorithm version */
+	__u32	bbr_inflight_lo;	/* lower short-term data volume bound */
+	__u32	bbr_inflight_hi;	/* higher long-term data volume bound */
+	__u32	bbr_extra_acked;	/* max excess packets ACKed in epoch */
+};
+
+/* TCP BBR congestion control bbr_phase as reported in netlink/ss stats. */
+enum tcp_bbr_phase {
+	BBR_PHASE_INVALID		= 0,
+	BBR_PHASE_STARTUP		= 1,
+	BBR_PHASE_DRAIN			= 2,
+	BBR_PHASE_PROBE_RTT		= 3,
+	BBR_PHASE_PROBE_BW_UP		= 4,
+	BBR_PHASE_PROBE_BW_DOWN		= 5,
+	BBR_PHASE_PROBE_BW_CRUISE	= 6,
+	BBR_PHASE_PROBE_BW_REFILL	= 7,
 };
 
 union tcp_cc_info {
diff --git a/misc/ss.c b/misc/ss.c
index e9d813596b91..5f413118f0dd 100644
--- a/misc/ss.c
+++ b/misc/ss.c
@@ -912,6 +912,7 @@ struct tcpstat {
 	bool		    app_limited;
 	struct dctcpstat    *dctcp;
 	struct tcp_bbr_info *bbr_info;
+	unsigned int	    bbr_info_len;
 };
 
 /* SCTP assocs share the same inode number with their parent endpoint. So if we
@@ -2585,6 +2586,29 @@ static void sctp_stats_print(struct sctp_info *s)
 		out(" fraginl:%d", s->sctpi_s_frag_interleave);
 }
 
+static const char* bbr_phase_to_str(enum tcp_bbr_phase phase)
+{
+	switch (phase) {
+	case BBR_PHASE_STARTUP:
+		return "STARTUP";
+	case BBR_PHASE_DRAIN:
+		return "DRAIN";
+	case BBR_PHASE_PROBE_RTT:
+		return "PROBE_RTT";
+	case BBR_PHASE_PROBE_BW_UP:
+		return "PROBE_BW_UP";
+	case BBR_PHASE_PROBE_BW_DOWN:
+		return "PROBE_BW_DOWN";
+	case BBR_PHASE_PROBE_BW_CRUISE:
+		return "PROBE_BW_CRUISE";
+	case BBR_PHASE_PROBE_BW_REFILL:
+		return "PROBE_BW_REFILL";
+	case BBR_PHASE_INVALID:
+	default:
+		return "INVALID";
+	}
+}
+
 static void tcp_stats_print(struct tcpstat *s)
 {
 	char b1[64];
@@ -2658,7 +2682,14 @@ static void tcp_stats_print(struct tcpstat *s)
 	}
 
 	if (s->bbr_info) {
-		__u64 bw;
+		/* All versions of the BBR algorithm use the INET_DIAG_BBRINFO
+		 * enum value. Later versions of the tcp_bbr_info struct are
+		 * backward-compatible with earlier versions, to allow older ss
+		 * binaries to print basic information for newer versions of
+		 * the algorithm. We use the size of the returned tcp_bbr_info
+		 * struct to decide how much to print.
+		 */
+		__u64 bw, bw_hi, bw_lo;
 
 		bw = s->bbr_info->bbr_bw_hi;
 		bw <<= 32;
@@ -2673,6 +2704,38 @@ static void tcp_stats_print(struct tcpstat *s)
 		if (s->bbr_info->bbr_cwnd_gain)
 			out(",cwnd_gain:%g",
 			    (double)s->bbr_info->bbr_cwnd_gain / 256.0);
+
+		if (s->bbr_info_len >=
+		    (offsetof(struct tcp_bbr_info, bbr_extra_acked) +
+		     sizeof(__u32))) {
+
+			bw_hi = s->bbr_info->bbr_bw_hi_msb;
+			bw_hi <<= 32;
+			bw_hi |= s->bbr_info->bbr_bw_hi_lsb;
+
+			bw_lo = s->bbr_info->bbr_bw_lo_msb;
+			bw_lo <<= 32;
+			bw_lo |= s->bbr_info->bbr_bw_lo_lsb;
+
+			out(",version:%u", s->bbr_info->bbr_version);
+			if (bw_hi != ~0UL)
+				out(",bw_hi:%sbps", sprint_bw(b1, bw_hi * 8.0));
+			if (bw_lo != ~0UL)
+				out(",bw_lo:%sbps", sprint_bw(b1, bw_lo * 8.0));
+			if (s->bbr_info->bbr_inflight_hi != ~0U)
+				out(",inflight_hi:%u",
+				    s->bbr_info->bbr_inflight_hi);
+			if (s->bbr_info->bbr_inflight_lo != ~0U)
+				out(",inflight_lo:%u",
+				    s->bbr_info->bbr_inflight_lo);
+			out(",extra_acked:%u", s->bbr_info->bbr_extra_acked);
+			out(",mode:%d", (int)s->bbr_info->bbr_mode);
+			out(",phase:%s",
+			    bbr_phase_to_str(
+				    (enum tcp_bbr_phase)
+				    s->bbr_info->bbr_phase));
+		}
+
 		out(")");
 	}
 
@@ -3147,6 +3210,7 @@ static void tcp_show_info(const struct nlmsghdr *nlh, struct inet_diag_msg *r,
 			s.bbr_info = calloc(1, sizeof(*s.bbr_info));
 			if (s.bbr_info && bbr_info)
 				memcpy(s.bbr_info, bbr_info, len);
+			s.bbr_info_len = len;
 		}
 
 		if (rtt > 0 && info->tcpi_snd_mss && info->tcpi_snd_cwnd) {
-- 
2.41.0.487.g6d72f3e995-goog