1 /*
2 * Copyright (c) 2017 Richard Palethorpe <rpalethorpe@suse.com>
3 *
4 * This program is free software: you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation, either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program 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
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program. If not, see <http://www.gnu.org/licenses/>.
16 */
17 /* Basic functionality test for tst_fuzzy_sync.h similar to the atomic tests
18 * (test15.c). One thread writes to the odd indexes of an array while the
19 * other writes to the even. If the threads are not synchronised then they
20 * will probably write to the wrong indexes as they share an index variable
21 * which they should take it in turns to update.
22 */
23
24 #include <stdlib.h>
25 #include "tst_test.h"
26 #include "tst_safe_pthread.h"
27 #include "tst_fuzzy_sync.h"
28
29 /* LOOPS * 2 + 1 must be less than INT_MAX */
30 #define LOOPS 0xFFFFULL
31
32 static volatile char seq[LOOPS * 2 + 1];
33 static struct tst_fzsync_pair pair;
34 static volatile int seq_n;
35 static volatile char last_wins;
36
setup(void)37 static void setup(void)
38 {
39 pair.exec_loops = LOOPS;
40 tst_fzsync_pair_init(&pair);
41 }
42
worker(void * v LTP_ATTRIBUTE_UNUSED)43 static void *worker(void *v LTP_ATTRIBUTE_UNUSED)
44 {
45 unsigned long long i;
46
47 for (i = 0; tst_fzsync_run_b(&pair); i++) {
48 tst_fzsync_start_race_b(&pair);
49 usleep(1);
50 last_wins = 'B';
51 tst_fzsync_end_race_b(&pair);
52 seq[seq_n] = 'B';
53 seq_n = (i + 1) * 2 % (int)LOOPS * 2;
54 }
55
56 if (i != LOOPS) {
57 tst_res(TFAIL,
58 "Worker performed wrong number of iterations: %lld != %lld",
59 i, LOOPS);
60 }
61
62 return NULL;
63 }
64
run(void)65 static void run(void)
66 {
67 unsigned int i, j, fail = 0, lost_race = 0;
68
69 tst_fzsync_pair_reset(&pair, worker);
70 for (i = 0; tst_fzsync_run_a(&pair); i++) {
71 tst_fzsync_start_race_a(&pair);
72 seq[seq_n] = 'A';
73 seq_n = i * 2 + 1;
74 last_wins = 'A';
75 tst_fzsync_end_race_a(&pair);
76 if (last_wins == 'B')
77 lost_race++;
78 }
79
80 tst_res(TINFO, "Checking sequence...");
81 for (i = 0; i < LOOPS; i++) {
82 j = i * 2;
83 if (seq[j] != 'A') {
84 tst_res(TFAIL, "Expected A, but found %c at %d",
85 seq[j], j);
86 fail = 1;
87 }
88 j = i * 2 + 1;
89 if (seq[j] != 'B') {
90 tst_res(TFAIL, "Expected A, but found %c at %d",
91 seq[j], j);
92 fail = 1;
93 }
94 }
95
96 if (!fail)
97 tst_res(TPASS, "Sequence is correct");
98
99 if (lost_race < 100)
100 tst_res(TFAIL, "A only lost the race %d times", lost_race);
101 else
102 tst_res(TPASS, "A lost the race %d times", lost_race);
103 }
104
cleanup(void)105 static void cleanup(void)
106 {
107 tst_fzsync_pair_cleanup(&pair);
108 }
109
110 static struct tst_test test = {
111 .setup = setup,
112 .cleanup = cleanup,
113 .test_all = run,
114 };
115