1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2020 Kyle Evans <kevans@FreeBSD.org>
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 #include <sys/types.h>
29 #include <sys/umtx.h>
30
31 #include <pthread.h>
32
33 #include <atf-c.h>
34
35 /*
36 * This is an implementation detail of _umtx_op(2), pulled from
37 * sys/kern/kern_umtx.c. The relevant bug observed that requests above the
38 * batch size would not function as intended, so it's important that this
39 * reflects the BATCH_SIZE configured there.
40 */
41 #define UMTX_OP_BATCH_SIZE 128
42 #define THREAD_COUNT ((UMTX_OP_BATCH_SIZE * 3) / 2)
43
44 static pthread_mutex_t static_mutex = PTHREAD_MUTEX_INITIALIZER;
45
46 static int batched_waiting;
47
48 static void *
batching_threadfunc(void * arg)49 batching_threadfunc(void *arg)
50 {
51
52 pthread_mutex_lock(&static_mutex);
53 ++batched_waiting;
54 pthread_mutex_unlock(&static_mutex);
55 _umtx_op(arg, UMTX_OP_WAIT_UINT_PRIVATE, 0, NULL, NULL);
56
57 return (NULL);
58 }
59
60 ATF_TC(batching);
ATF_TC_HEAD(batching,tc)61 ATF_TC_HEAD(batching, tc)
62 {
63 atf_tc_set_md_var(tc, "descr",
64 "Checks batching of UMTX_OP_NWAKE_PRIVATE");
65 }
ATF_TC_BODY(batching,tc)66 ATF_TC_BODY(batching, tc)
67 {
68 uintptr_t addrs[THREAD_COUNT];
69 uint32_t vals[THREAD_COUNT];
70 pthread_t threads[THREAD_COUNT];
71
72 for (int i = 0; i < THREAD_COUNT; i++) {
73 addrs[i] = (uintptr_t)&vals[i];
74 vals[i] = 0;
75 pthread_create(&threads[i], NULL, batching_threadfunc,
76 &vals[i]);
77 }
78
79 pthread_mutex_lock(&static_mutex);
80 while (batched_waiting != THREAD_COUNT) {
81 pthread_mutex_unlock(&static_mutex);
82 pthread_yield();
83 pthread_mutex_lock(&static_mutex);
84 }
85
86 /*
87 * Spin for another .50 seconds to make sure they're all safely in the
88 * kernel.
89 */
90 usleep(500000);
91
92 pthread_mutex_unlock(&static_mutex);
93 _umtx_op(addrs, UMTX_OP_NWAKE_PRIVATE, THREAD_COUNT, NULL, NULL);
94
95 for (int i = 0; i < THREAD_COUNT; i++) {
96 ATF_REQUIRE_EQ(0, pthread_join(threads[i], NULL));
97 }
98 }
99
ATF_TP_ADD_TCS(tp)100 ATF_TP_ADD_TCS(tp)
101 {
102
103 ATF_TP_ADD_TC(tp, batching);
104 return (atf_no_error());
105 }
106