1 | /* Test the interaction of fork and robust mutexes. |
2 | Copyright (C) 2017-2022 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 | |
19 | #include <errno.h> |
20 | #include <stdbool.h> |
21 | #include <stdio.h> |
22 | #include <support/check.h> |
23 | #include <support/test-driver.h> |
24 | #include <support/xthread.h> |
25 | #include <support/xunistd.h> |
26 | #include <sys/mman.h> |
27 | |
28 | /* Data shared between processes. */ |
29 | struct shared |
30 | { |
31 | pthread_mutex_t parent_mutex; |
32 | pthread_mutex_t child_mutex; |
33 | }; |
34 | |
35 | /* These flags control which mutex settings are enabled in the parent |
36 | and child (separately). */ |
37 | enum mutex_bits |
38 | { |
39 | mutex_pshared = 1, |
40 | mutex_robust = 2, |
41 | mutex_pi = 4, |
42 | mutex_check = 8, |
43 | |
44 | /* All bits combined. */ |
45 | mutex_all_bits = 15, |
46 | }; |
47 | |
48 | static void |
49 | mutex_init (pthread_mutex_t *mutex, int bits) |
50 | { |
51 | pthread_mutexattr_t attr; |
52 | xpthread_mutexattr_init (&attr); |
53 | if (bits & mutex_pshared) |
54 | xpthread_mutexattr_setpshared (&attr, PTHREAD_PROCESS_SHARED); |
55 | if (bits & mutex_robust) |
56 | xpthread_mutexattr_setrobust (&attr, PTHREAD_MUTEX_ROBUST); |
57 | if (bits & mutex_pi) |
58 | xpthread_mutexattr_setprotocol (&attr, PTHREAD_PRIO_INHERIT); |
59 | if (bits & mutex_check) |
60 | xpthread_mutexattr_settype (&attr, PTHREAD_MUTEX_ERRORCHECK); |
61 | xpthread_mutex_init (mutex, &attr); |
62 | xpthread_mutexattr_destroy (&attr); |
63 | } |
64 | |
65 | static void |
66 | one_test (int parent_bits, int child_bits, int nonshared_bits, |
67 | bool lock_nonshared, bool lock_child) |
68 | { |
69 | |
70 | struct shared *shared = xmmap (NULL, length: sizeof (*shared), |
71 | PROT_READ | PROT_WRITE, |
72 | MAP_ANONYMOUS | MAP_SHARED, fd: -1); |
73 | mutex_init (mutex: &shared->parent_mutex, bits: parent_bits); |
74 | mutex_init (mutex: &shared->child_mutex, bits: child_bits); |
75 | |
76 | /* Acquire the parent mutex in the parent. */ |
77 | xpthread_mutex_lock (mutex: &shared->parent_mutex); |
78 | |
79 | pthread_mutex_t nonshared_mutex; |
80 | mutex_init (mutex: &nonshared_mutex, bits: nonshared_bits); |
81 | if (lock_nonshared) |
82 | xpthread_mutex_lock (mutex: &nonshared_mutex); |
83 | |
84 | pid_t pid = xfork (); |
85 | if (pid == 0) |
86 | { |
87 | /* Child process. */ |
88 | if (lock_child) |
89 | xpthread_mutex_lock (mutex: &shared->child_mutex); |
90 | else |
91 | xmunmap (addr: shared, length: sizeof (*shared)); |
92 | if (lock_nonshared) |
93 | /* Reinitialize the non-shared mutex if it was locked in the |
94 | parent. */ |
95 | mutex_init (mutex: &nonshared_mutex, bits: nonshared_bits); |
96 | xpthread_mutex_lock (mutex: &nonshared_mutex); |
97 | /* For robust mutexes, the _exit call will perform the unlock |
98 | instead. */ |
99 | if (lock_child && !(child_bits & mutex_robust)) |
100 | xpthread_mutex_unlock (mutex: &shared->child_mutex); |
101 | _exit (0); |
102 | } |
103 | /* Parent process. */ |
104 | { |
105 | int status; |
106 | xwaitpid (pid, status: &status, flags: 0); |
107 | TEST_VERIFY (status == 0); |
108 | } |
109 | |
110 | if (parent_bits & mutex_check) |
111 | /* Test for expected self-deadlock. This is only possible to |
112 | detect if the mutex is error-checking. */ |
113 | TEST_VERIFY_EXIT (pthread_mutex_lock (&shared->parent_mutex) == EDEADLK); |
114 | |
115 | pid = xfork (); |
116 | if (pid == 0) |
117 | { |
118 | /* Child process. We can perform some checks only if we are |
119 | dealing with process-shared mutexes. */ |
120 | if (parent_bits & mutex_pshared) |
121 | /* It must not be possible to acquire the parent mutex. |
122 | |
123 | NB: This check touches a mutex which has been acquired in |
124 | the parent at fork time, so it might be deemed undefined |
125 | behavior, pending the resolution of Austin Groups issue |
126 | 1112. */ |
127 | TEST_VERIFY_EXIT (pthread_mutex_trylock (&shared->parent_mutex) |
128 | == EBUSY); |
129 | if (lock_child && (child_bits & mutex_robust)) |
130 | { |
131 | if (!(child_bits & mutex_pshared)) |
132 | /* No further tests possible. */ |
133 | _exit (0); |
134 | TEST_VERIFY_EXIT (pthread_mutex_lock (&shared->child_mutex) |
135 | == EOWNERDEAD); |
136 | xpthread_mutex_consistent (&shared->child_mutex); |
137 | } |
138 | else |
139 | /* We did not acquire the lock in the first child process, or |
140 | we unlocked the mutex again because the mutex is not a |
141 | robust mutex. */ |
142 | xpthread_mutex_lock (mutex: &shared->child_mutex); |
143 | xpthread_mutex_unlock (mutex: &shared->child_mutex); |
144 | _exit (0); |
145 | } |
146 | /* Parent process. */ |
147 | { |
148 | int status; |
149 | xwaitpid (pid, status: &status, flags: 0); |
150 | TEST_VERIFY (status == 0); |
151 | } |
152 | |
153 | if (lock_nonshared) |
154 | xpthread_mutex_unlock (mutex: &nonshared_mutex); |
155 | xpthread_mutex_unlock (mutex: &shared->parent_mutex); |
156 | xpthread_mutex_destroy (&shared->parent_mutex); |
157 | xpthread_mutex_destroy (&shared->child_mutex); |
158 | xpthread_mutex_destroy (&nonshared_mutex); |
159 | xmunmap (addr: shared, length: sizeof (*shared)); |
160 | } |
161 | |
162 | static int |
163 | do_test (void) |
164 | { |
165 | for (int parent_bits = 0; parent_bits <= mutex_all_bits; ++parent_bits) |
166 | for (int child_bits = 0; child_bits <= mutex_all_bits; ++child_bits) |
167 | for (int nonshared_bits = 0; nonshared_bits <= mutex_all_bits; |
168 | ++nonshared_bits) |
169 | for (int lock_nonshared = 0; lock_nonshared < 2; ++lock_nonshared) |
170 | for (int lock_child = 0; lock_child < 2; ++lock_child) |
171 | { |
172 | if (test_verbose) |
173 | printf (format: "info: parent_bits=0x%x child_bits=0x%x" |
174 | " nonshared_bits=0x%x%s%s\n" , |
175 | parent_bits, child_bits, nonshared_bits, |
176 | lock_nonshared ? " lock_nonshared" : "" , |
177 | lock_child ? " lock_child" : "" ); |
178 | one_test (parent_bits, child_bits, nonshared_bits, |
179 | lock_nonshared, lock_child); |
180 | } |
181 | return 0; |
182 | } |
183 | |
184 | #define TIMEOUT 100 |
185 | #include <support/test-driver.c> |
186 | |