1 | /* Test rdlock overflow. |
2 | Copyright (C) 2000-2022 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 <https://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 | |
33 | static pthread_rwlock_t lock = PTHREAD_RWLOCK_INITIALIZER; |
34 | static int eagain_returned = 0; |
35 | static int success_returned = 0; |
36 | |
37 | static void * |
38 | reader_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 (rwlock: &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 (s: "rdlock failed" ); |
59 | exit (1); |
60 | } |
61 | |
62 | nanosleep (requested_time: &delay, NULL); |
63 | |
64 | if (pthread_rwlock_unlock (rwlock: &lock) != 0) |
65 | { |
66 | puts (s: "unlock for reader failed" ); |
67 | exit (1); |
68 | } |
69 | } |
70 | |
71 | return NULL; |
72 | } |
73 | |
74 | |
75 | static int |
76 | do_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 (newthread: &thrd[n], NULL, start_routine: reader_thread, |
90 | arg: (void *) (long int) n) != 0) |
91 | { |
92 | puts (s: "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 (th: thrd[n], thread_return: &res) != 0) |
99 | { |
100 | puts (s: "reader join failed" ); |
101 | exit (1); |
102 | } |
103 | |
104 | if (atomic_load_relaxed (&eagain_returned) == 0) |
105 | { |
106 | puts (s: "EAGAIN has never been returned" ); |
107 | exit (1); |
108 | } |
109 | |
110 | if (atomic_load_relaxed (&success_returned) == 0) |
111 | { |
112 | puts (s: "rdlock was never successfully acquired" ); |
113 | exit (1); |
114 | } |
115 | |
116 | if (lock.__data.__readers != readers) |
117 | { |
118 | puts (s: "__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 | |