1 | /* Testing race while enabling lock elision. |
2 | Copyright (C) 2018-2024 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <https://www.gnu.org/licenses/>. */ |
18 | #include <stdio.h> |
19 | #include <stdlib.h> |
20 | #include <stdint.h> |
21 | #include <pthread.h> |
22 | #include <unistd.h> |
23 | #include <getopt.h> |
24 | #include <support/support.h> |
25 | #include <support/xthread.h> |
26 | |
27 | static pthread_barrier_t barrier; |
28 | static pthread_mutex_t mutex; |
29 | static long long int iteration_count = 1000000; |
30 | static unsigned int thread_count = 3; |
31 | |
32 | static void * |
33 | thr_func (void *arg) |
34 | { |
35 | long long int i; |
36 | for (i = 0; i < iteration_count; i++) |
37 | { |
38 | if ((uintptr_t) arg == 0) |
39 | { |
40 | xpthread_mutex_destroy (&mutex); |
41 | xpthread_mutex_init (&mutex, NULL); |
42 | } |
43 | |
44 | xpthread_barrier_wait (barrier: &barrier); |
45 | |
46 | /* Test if enabling lock elision works if it is enabled concurrently. |
47 | There was a race in FORCE_ELISION macro which leads to either |
48 | pthread_mutex_destroy returning EBUSY as the owner was recorded |
49 | by pthread_mutex_lock - in "normal mutex" code path - but was not |
50 | reset in pthread_mutex_unlock - in "elision" code path. |
51 | Or it leads to the assertion in nptl/pthread_mutex_lock.c: |
52 | assert (mutex->__data.__owner == 0); |
53 | Please ensure that the test is run with lock elision: |
54 | export GLIBC_TUNABLES=glibc.elision.enable=1 */ |
55 | xpthread_mutex_lock (mutex: &mutex); |
56 | xpthread_mutex_unlock (mutex: &mutex); |
57 | |
58 | xpthread_barrier_wait (barrier: &barrier); |
59 | } |
60 | return NULL; |
61 | } |
62 | |
63 | static int |
64 | do_test (void) |
65 | { |
66 | unsigned int i; |
67 | printf (format: "Starting %d threads to run %lld iterations.\n" , |
68 | thread_count, iteration_count); |
69 | |
70 | pthread_t *threads = xmalloc (n: thread_count * sizeof (pthread_t)); |
71 | xpthread_barrier_init (barrier: &barrier, NULL, count: thread_count); |
72 | xpthread_mutex_init (&mutex, NULL); |
73 | |
74 | for (i = 0; i < thread_count; i++) |
75 | threads[i] = xpthread_create (NULL, thread_func: thr_func, closure: (void *) (uintptr_t) i); |
76 | |
77 | for (i = 0; i < thread_count; i++) |
78 | xpthread_join (thr: threads[i]); |
79 | |
80 | xpthread_barrier_destroy (barrier: &barrier); |
81 | free (ptr: threads); |
82 | |
83 | return EXIT_SUCCESS; |
84 | } |
85 | |
86 | #define OPT_ITERATIONS 10000 |
87 | #define OPT_THREADS 10001 |
88 | #define CMDLINE_OPTIONS \ |
89 | { "iterations", required_argument, NULL, OPT_ITERATIONS }, \ |
90 | { "threads", required_argument, NULL, OPT_THREADS }, |
91 | static void |
92 | cmdline_process (int c) |
93 | { |
94 | long long int arg = strtoll (optarg, NULL, 0); |
95 | switch (c) |
96 | { |
97 | case OPT_ITERATIONS: |
98 | if (arg > 0) |
99 | iteration_count = arg; |
100 | break; |
101 | case OPT_THREADS: |
102 | if (arg > 0 && arg < 100) |
103 | thread_count = arg; |
104 | break; |
105 | } |
106 | } |
107 | #define CMDLINE_PROCESS cmdline_process |
108 | #define TIMEOUT 50 |
109 | #include <support/test-driver.c> |
110 | |