Merge branch 'tc-qevents' into next

Petr Machata  says:

====================

To allow configuring user-defined actions as a result of inner workings of
a qdisc, a concept of qevents was recently introduced to the kernel.
Qevents are attach points for TC blocks, where filters can be put that are
executed as the packet hits well-defined points in the qdisc algorithms.
The attached blocks can be shared, in a manner similar to clsact ingress
and egress blocks, arbitrary classifiers with arbitrary actions can be put
on them, etc.

For example:

 # tc qdisc add dev eth0 root handle 1: \
	red limit 500K avpkt 1K qevent early_drop block 10
 # tc filter add block 10 \
	matchall action mirred egress mirror dev eth1

This patch set introduces the corresponding iproute2 support. Patch #1 adds
the new netlink attribute enumerators. Patch #2 adds a set of helpers to
implement qevents, and #3 adds a generic documentation to tc.8. Patch #4
then adds two new qevents to the RED qdisc: mark and early_drop.

====================

Signed-off-by: David Ahern <dsahern@kernel.org>

man/man8/tc-red.8

@@ -17,7 +17,11 @@ packets
 rate
 .B ] [ probability
 chance
-.B ] [ adaptive ]
+.B ] [ adaptive ] [ qevent early_drop block
+index
+.B ] [ qevent mark block
+index
+.B ]
 
 .SH DESCRIPTION
 Random Early Detection is a classless qdisc which manages its queue size
@@ -134,6 +138,18 @@ Goal of Adaptive RED is to make 'probability' dynamic value between 1% and 50% t
 .B (max - min) / 2
 .fi
 
+.SH QEVENTS
+See tc (8) for some general notes about qevents. The RED qdisc supports the
+following qevents:
+
+.TP
+early_drop
+The associated block is executed when packets are early-dropped. This includes
+non-ECT packets in ECN mode.
+.TP
+mark
+The associated block is executed when packets are marked in ECN mode.
+
 .SH EXAMPLE
 
 .P

man/man8/tc.8

@@ -254,6 +254,25 @@ Traffic control filter that matches every packet. See
 .BR tc-matchall (8)
 for details.
 
+.SH QEVENTS
+Qdiscs may invoke user-configured actions when certain interesting events
+take place in the qdisc. Each qevent can either be unused, or can have a
+block attached to it. To this block are then attached filters using the "tc
+block BLOCK_IDX" syntax. The block is executed when the qevent associated
+with the attachment point takes place. For example, packet could be
+dropped, or delayed, etc., depending on the qdisc and the qevent in
+question.
+
+For example:
+.PP
+.RS
+tc qdisc add dev eth0 root handle 1: red limit 500K avpkt 1K \\
+   qevent early_drop block 10
+.RE
+.RS
+tc filter add block 10 matchall action mirred egress mirror dev eth1
+.RE
+
 .SH CLASSLESS QDISCS
 The classless qdiscs are:
 .TP

tc/Makefile

@@ -122,6 +122,7 @@ TCLIB += tc_red.o
 TCLIB += tc_cbq.o
 TCLIB += tc_estimator.o
 TCLIB += tc_stab.o
+TCLIB += tc_qevent.o
 
 CFLAGS += -DCONFIG_GACT -DCONFIG_GACT_PROB
 ifneq ($(IPT_LIB_DIR),)

tc/q_red.c

@@ -22,6 +22,7 @@
 
 #include "utils.h"
 #include "tc_util.h"
+#include "tc_qevent.h"
 
 #include "tc_red.h"
 
@@ -30,11 +31,20 @@ static void explain(void)
 	fprintf(stderr,
 		"Usage: ... red	limit BYTES [min BYTES] [max BYTES] avpkt BYTES [burst PACKETS]\n"
 		"		[adaptive] [probability PROBABILITY] [bandwidth KBPS]\n"
-		"		[ecn] [harddrop] [nodrop]\n");
+		"		[ecn] [harddrop] [nodrop]\n"
+		"		[qevent early_drop block IDX] [qevent mark block IDX]\n");
 }
 
 #define RED_SUPPORTED_FLAGS (TC_RED_HISTORIC_FLAGS | TC_RED_NODROP)
 
+static struct qevent_plain qe_early_drop = {};
+static struct qevent_plain qe_mark = {};
+static struct qevent_util qevents[] = {
+	QEVENT("early_drop", plain, &qe_early_drop, TCA_RED_EARLY_DROP_BLOCK),
+	QEVENT("mark", plain, &qe_mark, TCA_RED_MARK_BLOCK),
+	{},
+};
+
 static int red_parse_opt(struct qdisc_util *qu, int argc, char **argv,
 			 struct nlmsghdr *n, const char *dev)
 {
@@ -51,6 +61,8 @@ static int red_parse_opt(struct qdisc_util *qu, int argc, char **argv,
 	__u32 max_P;
 	struct rtattr *tail;
 
+	qevents_init(qevents);
+
 	while (argc > 0) {
 		if (strcmp(*argv, "limit") == 0) {
 			NEXT_ARG();
@@ -109,6 +121,11 @@ static int red_parse_opt(struct qdisc_util *qu, int argc, char **argv,
 			flags_bf.value |= TC_RED_ADAPTATIVE;
 		} else if (strcmp(*argv, "adaptive") == 0) {
 			flags_bf.value |= TC_RED_ADAPTATIVE;
+		} else if (matches(*argv, "qevent") == 0) {
+			NEXT_ARG();
+			if (qevent_parse(qevents, &argc, &argv))
+				return -1;
+			continue;
 		} else if (strcmp(*argv, "help") == 0) {
 			explain();
 			return -1;
@@ -162,6 +179,8 @@ static int red_parse_opt(struct qdisc_util *qu, int argc, char **argv,
 	max_P = probability * pow(2, 32);
 	addattr_l(n, 1024, TCA_RED_MAX_P, &max_P, sizeof(max_P));
 	addattr_l(n, 1024, TCA_RED_FLAGS, &flags_bf, sizeof(flags_bf));
+	if (qevents_dump(qevents, n))
+		return -1;
 	addattr_nest_end(n, tail);
 	return 0;
 }
@@ -203,12 +222,12 @@ static int red_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
 	print_uint(PRINT_JSON, "min", NULL, qopt->qth_min);
 	print_string(PRINT_FP, NULL, "min %s ", sprint_size(qopt->qth_min, b2));
 	print_uint(PRINT_JSON, "max", NULL, qopt->qth_max);
-	print_string(PRINT_FP, NULL, "max %s ", sprint_size(qopt->qth_max, b3));
+	print_string(PRINT_FP, NULL, "max %s", sprint_size(qopt->qth_max, b3));
 
 	tc_red_print_flags(qopt->flags);
 
 	if (show_details) {
-		print_uint(PRINT_ANY, "ewma", "ewma %u ", qopt->Wlog);
+		print_uint(PRINT_ANY, "ewma", " ewma %u ", qopt->Wlog);
 		if (max_P)
 			print_float(PRINT_ANY, "probability",
 				    "probability %lg ", max_P / pow(2, 32));
@@ -217,6 +236,11 @@ static int red_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
 		print_uint(PRINT_ANY, "Scell_log", "Scell_log %u",
 			   qopt->Scell_log);
 	}
+
+	qevents_init(qevents);
+	if (qevents_read(qevents, tb))
+		return -1;
+	qevents_print(qevents, f);
 	return 0;
 }
 

tc/tc_qevent.c

@@ -0,0 +1,202 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+
+/*
+ * Helpers for handling qevents.
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include "tc_qevent.h"
+#include "utils.h"
+
+void qevents_init(struct qevent_util *qevents)
+{
+	if (!qevents)
+		return;
+
+	for (; qevents->id; qevents++)
+		memset(qevents->data, 0, qevents->data_size);
+}
+
+int qevent_parse(struct qevent_util *qevents, int *p_argc, char ***p_argv)
+{
+	char **argv = *p_argv;
+	int argc = *p_argc;
+	const char *name = *argv;
+	int err;
+
+	if (!qevents)
+		goto out;
+
+	for (; qevents->id; qevents++) {
+		if (strcmp(name, qevents->id) == 0) {
+			NEXT_ARG();
+			err = qevents->parse_qevent(qevents, &argc, &argv);
+			if (err)
+				return err;
+
+			*p_argc = argc;
+			*p_argv = argv;
+			return 0;
+		}
+	}
+
+out:
+	fprintf(stderr, "Unknown qevent `%s'\n", name);
+	return -1;
+}
+
+int qevents_read(struct qevent_util *qevents, struct rtattr **tb)
+{
+	int err;
+
+	if (!qevents)
+		return 0;
+
+	for (; qevents->id; qevents++) {
+		if (tb[qevents->attr]) {
+			err = qevents->read_qevent(qevents, tb);
+			if (err)
+				return err;
+		}
+	}
+
+	return 0;
+}
+
+void qevents_print(struct qevent_util *qevents, FILE *f)
+{
+	int first = true;
+
+	if (!qevents)
+		return;
+
+	for (; qevents->id; qevents++) {
+		struct qevent_base *qeb = qevents->data;
+
+		if (qeb->block_idx) {
+			if (first) {
+				open_json_array(PRINT_JSON, "qevents");
+				first = false;
+			}
+
+			open_json_object(NULL);
+			print_string(PRINT_ANY, "kind", " qevent %s", qevents->id);
+			qevents->print_qevent(qevents, f);
+			close_json_object();
+		}
+	}
+
+	if (!first)
+		close_json_array(PRINT_ANY, "");
+}
+
+int qevents_dump(struct qevent_util *qevents, struct nlmsghdr *n)
+{
+	int err;
+
+	if (!qevents)
+		return 0;
+
+	for (; qevents->id; qevents++) {
+		struct qevent_base *qeb = qevents->data;
+
+		if (qeb->block_idx) {
+			err = qevents->dump_qevent(qevents, n);
+			if (err)
+				return err;
+		}
+	}
+
+	return 0;
+}
+
+static int parse_block_idx(const char *arg, struct qevent_base *qeb)
+{
+	if (qeb->block_idx) {
+		fprintf(stderr, "Qevent block index already specified\n");
+		return -1;
+	}
+
+	if (get_unsigned(&qeb->block_idx, arg, 10) || !qeb->block_idx) {
+		fprintf(stderr, "Illegal qevent block index\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+static int read_block_idx(struct rtattr *attr, struct qevent_base *qeb)
+{
+	if (qeb->block_idx) {
+		fprintf(stderr, "Qevent block index already specified\n");
+		return -1;
+	}
+
+	qeb->block_idx = rta_getattr_u32(attr);
+	if (!qeb->block_idx) {
+		fprintf(stderr, "Illegal qevent block index\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+static void print_block_idx(FILE *f, __u32 block_idx)
+{
+	print_uint(PRINT_ANY, "block", " block %u", block_idx);
+}
+
+int qevent_parse_plain(struct qevent_util *qu, int *p_argc, char ***p_argv)
+{
+	struct qevent_plain *qe = qu->data;
+	char **argv = *p_argv;
+	int argc = *p_argc;
+
+	if (qe->base.block_idx) {
+		fprintf(stderr, "Duplicate qevent\n");
+		return -1;
+	}
+
+	while (argc > 0) {
+		if (strcmp(*argv, "block") == 0) {
+			NEXT_ARG();
+			if (parse_block_idx(*argv, &qe->base))
+				return -1;
+		} else {
+			break;
+		}
+		NEXT_ARG_FWD();
+	}
+
+	if (!qe->base.block_idx) {
+		fprintf(stderr, "Unspecified qevent block index\n");
+		return -1;
+	}
+
+	*p_argc = argc;
+	*p_argv = argv;
+	return 0;
+}
+
+int qevent_read_plain(struct qevent_util *qu, struct rtattr **tb)
+{
+	struct qevent_plain *qe = qu->data;
+
+	return read_block_idx(tb[qu->attr], &qe->base);
+}
+
+void qevent_print_plain(struct qevent_util *qu, FILE *f)
+{
+	struct qevent_plain *qe = qu->data;
+
+	print_block_idx(f, qe->base.block_idx);
+}
+
+int qevent_dump_plain(struct qevent_util *qu, struct nlmsghdr *n)
+{
+	struct qevent_plain *qe = qu->data;
+
+	return addattr32(n, 1024, qu->attr, qe->base.block_idx);
+}

tc/tc_qevent.h

@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _TC_QEVENT_H_
+#define _TC_QEVENT_H_
+
+#include <linux/types.h>
+#include <libnetlink.h>
+
+struct qevent_base {
+	__u32 block_idx;
+};
+
+struct qevent_util {
+	const char *id;
+	int (*parse_qevent)(struct qevent_util *qu, int *argc, char ***argv);
+	int (*read_qevent)(struct qevent_util *qu, struct rtattr **tb);
+	void (*print_qevent)(struct qevent_util *qu, FILE *f);
+	int (*dump_qevent)(struct qevent_util *qu, struct nlmsghdr *n);
+	size_t data_size;
+	void *data;
+	int attr;
+};
+
+#define QEVENT(_name, _form, _data, _attr)				\
+	{								\
+		.id = _name,						\
+		.parse_qevent = qevent_parse_##_form,			\
+		.read_qevent = qevent_read_##_form,			\
+		.print_qevent = qevent_print_##_form,			\
+		.dump_qevent = qevent_dump_##_form,			\
+		.data_size = sizeof(struct qevent_##_form),		\
+		.data = _data,						\
+		.attr = _attr,						\
+	}
+
+void qevents_init(struct qevent_util *qevents);
+int qevent_parse(struct qevent_util *qevents, int *p_argc, char ***p_argv);
+int qevents_read(struct qevent_util *qevents, struct rtattr **tb);
+int qevents_dump(struct qevent_util *qevents, struct nlmsghdr *n);
+void qevents_print(struct qevent_util *qevents, FILE *f);
+
+struct qevent_plain {
+	struct qevent_base base;
+};
+int qevent_parse_plain(struct qevent_util *qu, int *p_argc, char ***p_argv);
+int qevent_read_plain(struct qevent_util *qu, struct rtattr **tb);
+void qevent_print_plain(struct qevent_util *qu, FILE *f);
+int qevent_dump_plain(struct qevent_util *qu, struct nlmsghdr *n);
+
+#endif