Differential D27231 Diff 79637 head/lib/libthr/tests/umtx_op_test.c

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head/lib/libthr/tests/umtx_op_test.c

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				/*-
				* SPDX-License-Identifier: BSD-2-Clause
				*
				* Copyright (c) 2020 Kyle Evans <kevans@FreeBSD.org>
				*
				* 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/cdefs.h>
				__FBSDID("$FreeBSD$");

				#include <sys/types.h>
				#include <sys/umtx.h>

				#include <pthread.h>

				#include <atf-c.h>

				/*
				* This is an implementation detail of _umtx_op(2), pulled from
				* sys/kern/kern_umtx.c. The relevant bug observed that requests above the
				* batch side would not function as intended, so it's important that this
				* reflects the BATCH_SIZE configured there.
				*/
				#define UMTX_OP_BATCH_SIZE 128
				#define THREAD_COUNT ((UMTX_OP_BATCH_SIZE * 3) / 2)

				static pthread_mutex_t static_mutex = PTHREAD_MUTEX_INITIALIZER;

				static int batched_waiting;

				static void *
				batching_threadfunc(void *arg)
				{

				pthread_mutex_lock(&static_mutex);
				++batched_waiting;
				pthread_mutex_unlock(&static_mutex);
				_umtx_op(arg, UMTX_OP_WAIT_UINT_PRIVATE, 0, NULL, NULL);

				return (NULL);
				}

				ATF_TC(batching);
				ATF_TC_HEAD(batching, tc)
				{
				atf_tc_set_md_var(tc, "descr",
				"Checks batching of UMTX_OP_NWAKE_PRIVATE");
				}
				ATF_TC_BODY(batching, tc)
				{
				uintptr_t addrs[THREAD_COUNT];
				uint32_t vals[THREAD_COUNT];
				pthread_t threads[THREAD_COUNT];

				for (int i = 0; i < THREAD_COUNT; i++) {
				addrs[i] = (uintptr_t)&vals[i];
				vals[i] = 0;
				pthread_create(&threads[i], NULL, batching_threadfunc,
				&vals[i]);
				}

				pthread_mutex_lock(&static_mutex);
				while (batched_waiting != THREAD_COUNT) {
				pthread_mutex_unlock(&static_mutex);
				pthread_yield();
				pthread_mutex_lock(&static_mutex);
				}

				/*
				* Spin for another .50 seconds to make sure they're all safely in the
				* kernel.
				*/
				usleep(500000);

				pthread_mutex_unlock(&static_mutex);
				_umtx_op(addrs, UMTX_OP_NWAKE_PRIVATE, THREAD_COUNT, NULL, NULL);

				for (int i = 0; i < THREAD_COUNT; i++) {
				ATF_REQUIRE_EQ(0, pthread_join(threads[i], NULL));
				}
				}

				ATF_TP_ADD_TCS(tp)
				{

				ATF_TP_ADD_TC(tp, batching);
				return (atf_no_error());
				}