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1/* Test rdlock overflow.
2 Copyright (C) 2000-2019 Free Software Foundation, Inc.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1 of the
7 License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; see the file COPYING.LIB. If
16 not, see <http://www.gnu.org/licenses/>. */
17
18#include <errno.h>
19#include <error.h>
20#include <pthread.h>
21#include <stdio.h>
22#include <stdlib.h>
23#include <time.h>
24#include <unistd.h>
25#include <pthreadP.h>
26
27
28#define NREADERS 15
29#define READTRIES 5000
30
31#define DELAY 1000000
32
33static pthread_rwlock_t lock = PTHREAD_RWLOCK_INITIALIZER;
34static int eagain_returned = 0;
35static int success_returned = 0;
36
37static void *
38reader_thread (void *nr)
39{
40 struct timespec delay;
41 int n;
42
43 delay.tv_sec = 0;
44 delay.tv_nsec = DELAY;
45
46 for (n = 0; n < READTRIES; ++n)
47 {
48 int err = pthread_rwlock_rdlock (&lock);
49 if (err == EAGAIN)
50 {
51 atomic_store_relaxed (&eagain_returned, 1);
52 continue;
53 }
54 else if (err == 0)
55 atomic_store_relaxed (&success_returned, 1);
56 else
57 {
58 puts ("rdlock failed");
59 exit (1);
60 }
61
62 nanosleep (&delay, NULL);
63
64 if (pthread_rwlock_unlock (&lock) != 0)
65 {
66 puts ("unlock for reader failed");
67 exit (1);
68 }
69 }
70
71 return NULL;
72}
73
74
75static int
76do_test (void)
77{
78 pthread_t thrd[NREADERS];
79 int n;
80 void *res;
81
82 /* Set the rwlock so that it's close to a reader overflow.
83 PTHREAD_RWLOCK_WRPHASE and PTHREAD_RWLOCK_WRLOCK are zero initially. */
84 unsigned int readers = PTHREAD_RWLOCK_READER_OVERFLOW
85 - ((NREADERS / 3) << PTHREAD_RWLOCK_READER_SHIFT);
86 lock.__data.__readers = readers;
87
88 for (n = 0; n < NREADERS; ++n)
89 if (pthread_create (&thrd[n], NULL, reader_thread,
90 (void *) (long int) n) != 0)
91 {
92 puts ("reader create failed");
93 exit (1);
94 }
95
96 /* Wait for all the threads. */
97 for (n = 0; n < NREADERS; ++n)
98 if (pthread_join (thrd[n], &res) != 0)
99 {
100 puts ("reader join failed");
101 exit (1);
102 }
103
104 if (atomic_load_relaxed (&eagain_returned) == 0)
105 {
106 puts ("EAGAIN has never been returned");
107 exit (1);
108 }
109
110 if (atomic_load_relaxed (&success_returned) == 0)
111 {
112 puts ("rdlock was never successfully acquired");
113 exit (1);
114 }
115
116 if (lock.__data.__readers != readers)
117 {
118 puts ("__readers in rwlock differs from initial value");
119 exit (1);
120 }
121
122 return 0;
123}
124
125#define TIMEOUT 100
126#define TEST_FUNCTION do_test ()
127#include "../test-skeleton.c"
128

Warning: That file was not part of the compilation database. It may have many parsing errors.