buf_ring: Add a threaded test

Add a threaded test for buf_ring.h used to help find issues with it on
architectures with a weak memory order.

Sponsored by:	Arm Ltd
Differential Revision:	https://reviews.freebsd.org/D46158

tools/test/buf_ring/Makefile

@@ -0,0 +1,7 @@
+PROG=	buf_ring_test
+WARNS=	6
+MAN=
+
+LDFLAGS+=-pthread
+
+.include <bsd.prog.mk>

tools/test/buf_ring/buf_ring_test.c

@@ -0,0 +1,322 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 Arm Ltd.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ */
+
+#include <sys/types.h>
+#include <sys/errno.h>
+
+#include <machine/atomic.h>
+#include <machine/cpu.h>
+#include <machine/cpufunc.h>
+
+#include <assert.h>
+#include <err.h>
+#include <getopt.h>
+#include <pthread.h>
+#include <stdarg.h>
+#include <stdatomic.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/* #define DEBUG_BUFRING */
+
+#ifdef DEBUG_BUFRING
+static void
+panic(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	fprintf(stderr, "\n");
+	exit(1);
+}
+#endif
+
+static void
+critical_enter(void)
+{
+}
+
+static void
+critical_exit(void)
+{
+}
+
+#include "../../../sys/sys/buf_ring.h"
+
+#define	PROD_ITERATIONS	100000000
+
+static enum {
+	CT_UNKNOWN,
+	CT_MC,
+	CT_MC_MT,
+	CT_SC,
+	CT_PEEK,
+	CT_PEEK_CLEAR,
+} cons_type = CT_UNKNOWN;
+
+static unsigned int prod_count;
+
+static struct buf_ring *br;
+static _Atomic bool prod_done = false;
+static _Atomic int prod_done_count = 0;
+static _Atomic size_t total_cons_count = 0;
+
+static uint64_t *mt_seen;
+
+static void *
+producer(void *arg)
+{
+	int id, rv;
+
+	id = (int)(uintptr_t)arg;
+
+	for (size_t i = 0; i < PROD_ITERATIONS;) {
+		rv = buf_ring_enqueue(br, (void *)(i * prod_count + 1 + id));
+		if (rv == 0) {
+			i++;
+		}
+	}
+	if ((unsigned int)atomic_fetch_add(&prod_done_count, 1) ==
+	    (prod_count - 1))
+		atomic_store(&prod_done, true);
+
+	return (NULL);
+}
+
+static void *
+consumer(void *arg)
+{
+	void *val;
+	size_t *max_vals;
+	size_t consume_count, curr;
+	int id;
+
+	(void)arg;
+
+	max_vals = calloc(prod_count, sizeof(*max_vals));
+	assert(max_vals != NULL);
+
+	/* Set the initial value to be the expected value */
+	for (unsigned int i = 1; i < prod_count; i++) {
+		max_vals[i] = (int)(i - prod_count);
+	}
+
+	consume_count = 0;
+	while (!atomic_load(&prod_done) || !buf_ring_empty(br)) {
+		switch(cons_type) {
+		case CT_MC:
+		case CT_MC_MT:
+			val = buf_ring_dequeue_mc(br);
+			break;
+		case CT_SC:
+			val = buf_ring_dequeue_sc(br);
+			break;
+		case CT_PEEK:
+			val = buf_ring_peek(br);
+			if (val != NULL)
+				buf_ring_advance_sc(br);
+			break;
+		case CT_PEEK_CLEAR:
+			val = buf_ring_peek_clear_sc(br);
+			if (val != NULL)
+				buf_ring_advance_sc(br);
+			break;
+		case CT_UNKNOWN:
+			__unreachable();
+		}
+		if (val != NULL) {
+			consume_count++;
+			curr = (size_t)(uintptr_t)val;
+			id = curr % prod_count;
+			if (cons_type != CT_MC_MT) {
+				if (curr != max_vals[id] + prod_count)
+					printf("Incorrect val: %zu Expect: %zu "
+					    "Difference: %zd\n", curr,
+					    max_vals[id] + prod_count,
+					    curr - max_vals[id] - prod_count);
+			} else {
+				size_t idx, bit;
+
+				idx = ((size_t)(uintptr_t)val - 1) /
+				    (sizeof(*mt_seen) * NBBY);
+				bit = ((size_t)(uintptr_t)val - 1) %
+				    (sizeof(*mt_seen) * NBBY);
+
+				if (atomic_testandset_64(&mt_seen[idx], bit))
+					printf("Repeat ID: %zx\n", (size_t)(uintptr_t)val);
+			}
+
+			max_vals[id] = (uintptr_t)val;
+		}
+	}
+
+	atomic_fetch_add(&total_cons_count, consume_count);
+
+	for (unsigned int i = 0; i < prod_count; i++)
+		printf("max[%d] = %zu\n", i, max_vals[i]);
+
+	return (NULL);
+}
+
+static struct option longopts[] = {
+	{ "buf-size",	required_argument,	NULL,	'b'	},
+	{ "cons-type",	required_argument,	NULL,	'c'	},
+	{ "prod-count",	required_argument,	NULL,	'p'	},
+	{ "help",	no_argument,		NULL,	'h'	},
+	{ NULL,		0,			NULL,	 0	},
+};
+
+static void
+usage(void)
+{
+	errx(1, "test --cons-type=<mc|mc-mt|sc|peek|peek-clear> --prod-count=<prod thread count> [--buf-size=<buf_ring size>]");
+}
+
+static uint32_t
+next_power_of_2(uint32_t x)
+{
+	x--;
+	x |= x >> 1;
+	x |= x >> 2;
+	x |= x >> 4;
+	x |= x >> 8;
+	x |= x >> 16;
+	x++;
+	return (x);
+}
+
+int
+main(int argc, char *argv[])
+{
+	pthread_t *prod;
+	pthread_t cons[2];
+	const char *errstr;
+	uint32_t size;
+	int ch, ret;
+
+	size = 0;
+	while ((ch = getopt_long(argc, argv, "bf:", longopts, NULL)) != -1) {
+		switch(ch) {
+		case 'b':
+			errstr = NULL;
+			size = strtonum(optarg, 1, UINT_MAX, &errstr);
+			if (errstr != NULL) {
+				errx(1, "--bufsize=%s: %s", optarg, errstr);
+			}
+			if (!powerof2(size)) {
+				errx(1, "--bufsize needs a power of 2 size");
+			}
+			break;
+		case 'c':
+			if (strcmp(optarg, "mc") == 0) {
+				cons_type = CT_MC;
+			} else if (strcmp(optarg, "mc-mt") == 0) {
+				cons_type = CT_MC_MT;
+			} else if (strcmp(optarg, "sc") == 0) {
+				cons_type = CT_SC;
+			} else if (strcmp(optarg, "peek") == 0) {
+				cons_type = CT_PEEK;
+			} else if (strcmp(optarg, "peek-clear") == 0) {
+				cons_type = CT_PEEK_CLEAR;
+			} else {
+				errx(1, "Unknown --cons-type: %s", optarg);
+			}
+			break;
+		case 'p':
+			errstr = NULL;
+			prod_count = strtonum(optarg, 1, UINT_MAX, &errstr);
+			if (errstr != NULL) {
+				errx(1, "--prod-count=%s: %s", optarg, errstr);
+			}
+			break;
+		case 'h':
+		default:
+			usage();
+		}
+	}
+	argc -= optind;
+	argv += optind;
+
+	if (cons_type == CT_UNKNOWN)
+		errx(1, "No cons-type set");
+
+	if (prod_count == 0)
+		errx(1, "prod-count is not set");
+
+	if (size == 0)
+		size = next_power_of_2(prod_count);
+
+	if (cons_type == CT_MC_MT) {
+		size_t entries;
+
+		entries = (size_t)PROD_ITERATIONS * prod_count;
+		entries = roundup2(entries, sizeof(*mt_seen));
+		mt_seen = calloc(entries / (sizeof(*mt_seen) * NBBY),
+		    sizeof(*mt_seen));
+	}
+
+	br = buf_ring_alloc(size);
+
+	ret = pthread_create(&cons[0], NULL, consumer, NULL);
+	assert(ret == 0);
+	if (cons_type == CT_MC_MT) {
+		ret = pthread_create(&cons[1], NULL, consumer, NULL);
+		assert(ret == 0);
+	}
+
+	prod = calloc(prod_count, sizeof(*prod));
+	assert(prod != NULL);
+	for (unsigned i = 0; i < prod_count; i++) {
+		ret = pthread_create(&prod[i], NULL, producer,
+		    (void *)(uintptr_t)i);
+		assert(ret == 0);
+	}
+
+	for (unsigned int i = 0; i < prod_count; i++) {
+		ret = pthread_join(prod[i], NULL);
+		assert(ret == 0);
+	}
+	ret = pthread_join(cons[0], NULL);
+	assert(ret == 0);
+	if (cons_type == CT_MC_MT) {
+		ret = pthread_join(cons[1], NULL);
+		assert(ret == 0);
+	}
+
+	printf("Expected: %zu\n", (size_t)PROD_ITERATIONS * prod_count);
+	printf("Received: %zu\n", total_cons_count);
+
+	buf_ring_free(br);
+
+	return (0);
+}

tools/test/buf_ring/run.sh

@@ -0,0 +1,16 @@
+#!/bin/sh
+
+run() {
+	kind=$1
+	echo Testing ${kind}
+	buf_ring_test --cons-type=${kind} --prod-count=2 --buf-size=4
+}
+
+OBJDIR=$(make -V.OBJDIR)
+export PATH=${OBJDIR}:${PATH}
+
+run mc
+run sc
+run peek
+run peek-clear
+run mc-mt