]>
Commit | Line | Data |
---|---|---|
1 | /* Test case for async-signal-safe fork (with respect to malloc). | |
2 | Copyright (C) 2016-2019 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 License as | |
7 | published by the Free Software Foundation; either version 2.1 of the | |
8 | 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; see the file COPYING.LIB. If | |
17 | not, see <http://www.gnu.org/licenses/>. */ | |
18 | ||
19 | /* This test will fail if the process is multi-threaded because we | |
20 | only have an async-signal-safe fork in the single-threaded case | |
21 | (where we skip acquiring the malloc heap locks). | |
22 | ||
23 | This test only checks async-signal-safety with regards to malloc; | |
24 | other, more rarely-used glibc subsystems could have locks which | |
25 | still make fork unsafe, even in single-threaded processes. */ | |
26 | ||
27 | #include <errno.h> | |
28 | #include <sched.h> | |
29 | #include <signal.h> | |
30 | #include <stdbool.h> | |
31 | #include <stdio.h> | |
32 | #include <stdlib.h> | |
33 | #include <string.h> | |
34 | #include <sys/wait.h> | |
35 | #include <time.h> | |
36 | #include <unistd.h> | |
37 | #include <array_length.h> | |
38 | #include <support/check.h> | |
39 | #include <support/support.h> | |
40 | #include <support/xthread.h> | |
41 | #include <support/xunistd.h> | |
42 | ||
43 | /* How many malloc objects to keep arond. */ | |
44 | enum { malloc_objects = 1009 }; | |
45 | ||
46 | /* The maximum size of an object. */ | |
47 | enum { malloc_maximum_size = 70000 }; | |
48 | ||
49 | /* How many iterations the test performs before exiting. */ | |
50 | enum { iterations = 10000 }; | |
51 | ||
52 | /* Barrier for synchronization with the processes sending SIGUSR1 | |
53 | signals, to make it more likely that the signals arrive during a | |
54 | fork/free/malloc call. */ | |
55 | static struct { pthread_barrier_t barrier; } *shared; | |
56 | ||
57 | /* Set to 1 if SIGUSR1 is received. Used to detect a signal during | |
58 | fork/free/malloc. */ | |
59 | static volatile sig_atomic_t sigusr1_received; | |
60 | ||
61 | /* Periodically set to 1, to indicate that the process is making | |
62 | progress. Checked by liveness_signal_handler. */ | |
63 | static volatile sig_atomic_t progress_indicator = 1; | |
64 | ||
65 | static void | |
66 | sigusr1_handler (int signo) | |
67 | { | |
68 | sigusr1_received = 1; | |
69 | ||
70 | /* Perform a fork with a trivial subprocess. */ | |
71 | pid_t pid = fork (); | |
72 | if (pid == -1) | |
73 | { | |
74 | write_message ("error: fork\n"); | |
75 | abort (); | |
76 | } | |
77 | if (pid == 0) | |
78 | _exit (0); | |
79 | int status; | |
80 | int ret = TEMP_FAILURE_RETRY (waitpid (pid, &status, 0)); | |
81 | if (ret < 0) | |
82 | { | |
83 | write_message ("error: waitpid\n"); | |
84 | abort (); | |
85 | } | |
86 | if (status != 0) | |
87 | { | |
88 | write_message ("error: unexpected exit status from subprocess\n"); | |
89 | abort (); | |
90 | } | |
91 | } | |
92 | ||
93 | static void | |
94 | liveness_signal_handler (int signo) | |
95 | { | |
96 | if (progress_indicator) | |
97 | progress_indicator = 0; | |
98 | else | |
99 | write_message ("warning: process seems to be stuck\n"); | |
100 | } | |
101 | ||
102 | /* Send SIGNO to the parent process. If SLEEP, wait a second between | |
103 | signals, otherwise use barriers to delay sending signals. */ | |
104 | static void | |
105 | __attribute__ ((noreturn)) | |
106 | signal_sender (int signo, bool sleep) | |
107 | { | |
108 | pid_t target = getppid (); | |
109 | while (true) | |
110 | { | |
111 | if (!sleep) | |
112 | xpthread_barrier_wait (&shared->barrier); | |
113 | if (kill (target, signo) != 0) | |
114 | { | |
115 | dprintf (STDOUT_FILENO, "error: kill: %m\n"); | |
116 | abort (); | |
117 | } | |
118 | if (sleep) | |
119 | usleep (1 * 1000 * 1000); | |
120 | else | |
121 | xpthread_barrier_wait (&shared->barrier); | |
122 | } | |
123 | } | |
124 | ||
125 | static int | |
126 | do_test (void) | |
127 | { | |
128 | /* shared->barrier is intialized along with sigusr1_sender_pids | |
129 | below. */ | |
130 | shared = support_shared_allocate (sizeof (*shared)); | |
131 | ||
132 | struct sigaction action = | |
133 | { | |
134 | .sa_handler = sigusr1_handler, | |
135 | }; | |
136 | sigemptyset (&action.sa_mask); | |
137 | ||
138 | if (sigaction (SIGUSR1, &action, NULL) != 0) | |
139 | { | |
140 | printf ("error: sigaction: %m"); | |
141 | return 1; | |
142 | } | |
143 | ||
144 | action.sa_handler = liveness_signal_handler; | |
145 | if (sigaction (SIGUSR2, &action, NULL) != 0) | |
146 | { | |
147 | printf ("error: sigaction: %m"); | |
148 | return 1; | |
149 | } | |
150 | ||
151 | pid_t sigusr2_sender_pid = xfork (); | |
152 | if (sigusr2_sender_pid == 0) | |
153 | signal_sender (SIGUSR2, true); | |
154 | ||
155 | /* Send SIGUSR1 signals from several processes. Hopefully, one | |
156 | signal will hit one of the ciritical functions. Use a barrier to | |
157 | avoid sending signals while not running fork/free/malloc. */ | |
158 | pid_t sigusr1_sender_pids[5]; | |
159 | { | |
160 | pthread_barrierattr_t attr; | |
161 | xpthread_barrierattr_init (&attr); | |
162 | xpthread_barrierattr_setpshared (&attr, PTHREAD_PROCESS_SHARED); | |
163 | xpthread_barrier_init (&shared->barrier, &attr, | |
164 | array_length (sigusr1_sender_pids) + 1); | |
165 | xpthread_barrierattr_destroy (&attr); | |
166 | } | |
167 | for (size_t i = 0; i < array_length (sigusr1_sender_pids); ++i) | |
168 | { | |
169 | sigusr1_sender_pids[i] = fork (); | |
170 | if (sigusr1_sender_pids[i] == 0) | |
171 | signal_sender (SIGUSR1, false); | |
172 | } | |
173 | ||
174 | void *objects[malloc_objects] = {}; | |
175 | unsigned int fork_signals = 0; | |
176 | unsigned int free_signals = 0; | |
177 | unsigned int malloc_signals = 0; | |
178 | unsigned seed = 1; | |
179 | for (int i = 0; i < iterations; ++i) | |
180 | { | |
181 | progress_indicator = 1; | |
182 | int slot = rand_r (&seed) % malloc_objects; | |
183 | size_t size = rand_r (&seed) % malloc_maximum_size; | |
184 | ||
185 | /* Occasionally do a fork first, to catch deadlocks there as | |
186 | well (see bug 24161). */ | |
187 | bool do_fork = (rand_r (&seed) % 7) == 0; | |
188 | ||
189 | xpthread_barrier_wait (&shared->barrier); | |
190 | if (do_fork) | |
191 | { | |
192 | sigusr1_received = 0; | |
193 | pid_t pid = xfork (); | |
194 | if (sigusr1_received) | |
195 | ++fork_signals; | |
196 | if (pid == 0) | |
197 | _exit (0); | |
198 | int status; | |
199 | int ret = TEMP_FAILURE_RETRY (waitpid (pid, &status, 0)); | |
200 | if (ret < 0) | |
201 | FAIL_EXIT1 ("waitpid: %m"); | |
202 | TEST_COMPARE (status, 0); | |
203 | } | |
204 | sigusr1_received = 0; | |
205 | free (objects[slot]); | |
206 | if (sigusr1_received) | |
207 | ++free_signals; | |
208 | sigusr1_received = 0; | |
209 | objects[slot] = malloc (size); | |
210 | if (sigusr1_received) | |
211 | ++malloc_signals; | |
212 | xpthread_barrier_wait (&shared->barrier); | |
213 | ||
214 | if (objects[slot] == NULL) | |
215 | { | |
216 | printf ("error: malloc: %m\n"); | |
217 | for (size_t i = 0; i < array_length (sigusr1_sender_pids); ++i) | |
218 | kill (sigusr1_sender_pids[i], SIGKILL); | |
219 | kill (sigusr2_sender_pid, SIGKILL); | |
220 | return 1; | |
221 | } | |
222 | } | |
223 | ||
224 | /* Clean up allocations. */ | |
225 | for (int slot = 0; slot < malloc_objects; ++slot) | |
226 | free (objects[slot]); | |
227 | ||
228 | for (size_t i = 0; i < array_length (sigusr1_sender_pids); ++i) | |
229 | kill (sigusr1_sender_pids[i], SIGKILL); | |
230 | kill (sigusr2_sender_pid, SIGKILL); | |
231 | ||
232 | printf ("info: signals received during fork: %u\n", fork_signals); | |
233 | printf ("info: signals received during free: %u\n", free_signals); | |
234 | printf ("info: signals received during malloc: %u\n", malloc_signals); | |
235 | ||
236 | /* Do not destroy the barrier because of the SIGKILL above, which | |
237 | may have left the barrier in an inconsistent state. */ | |
238 | support_shared_free (shared); | |
239 | ||
240 | return 0; | |
241 | } | |
242 | ||
243 | #define TIMEOUT 100 | |
244 | #include <support/test-driver.c> |