1 /*
2 * eventfd-sem by Davide Libenzi (Simple test for eventfd sempahore)
3 * Copyright (C) 2009 Davide Libenzi
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program 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
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 *
19 * Davide Libenzi <davidel@xmailserver.org>
20 * Reference: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=bcd0b235bf3808dec5115c381cd55568f63b85f0
21 * Reference: http://www.xmailserver.org/eventfd-sem.c
22 * eventfd: testing improved support for semaphore-like behavior in linux-2.6.30
23 *
24 */
25
26 #include <sys/types.h>
27 #include <sys/syscall.h>
28 #include <sys/stat.h>
29 #include <sys/wait.h>
30 #include <fcntl.h>
31 #include <stdlib.h>
32 #include <stdio.h>
33 #include <string.h>
34 #include <unistd.h>
35 #include <errno.h>
36 #include <inttypes.h>
37
38 #include "test.h"
39 #include "lapi/syscalls.h"
40
41 char *TCID = "eventfd2_03";
42 int TST_TOTAL = 1;
43
44 #ifndef EFD_SEMLIKE
45 #define EFD_SEMLIKE (1 << 0)
46 #endif
47
48 /* Dummy function as syscall from linux_syscall_numbers.h uses cleanup(). */
cleanup(void)49 void cleanup(void)
50 {
51 }
52
eventfd2(int count,int flags)53 static int eventfd2(int count, int flags)
54 {
55 return ltp_syscall(__NR_eventfd2, count, flags);
56 }
57
xsem_wait(int fd)58 static void xsem_wait(int fd)
59 {
60 u_int64_t cntr;
61
62 if (read(fd, &cntr, sizeof(cntr)) != sizeof(cntr)) {
63 perror("reading eventfd");
64 exit(1);
65 }
66 fprintf(stdout, "[%u] wait completed on %d: count=%" PRIu64 "\n",
67 getpid(), fd, cntr);
68 }
69
xsem_post(int fd,int count)70 static void xsem_post(int fd, int count)
71 {
72 u_int64_t cntr = count;
73
74 if (write(fd, &cntr, sizeof(cntr)) != sizeof(cntr)) {
75 perror("writing eventfd");
76 exit(1);
77 }
78 }
79
sem_player(int fd1,int fd2)80 static void sem_player(int fd1, int fd2)
81 {
82 fprintf(stdout, "[%u] posting 1 on %d\n", getpid(), fd1);
83 xsem_post(fd1, 1);
84
85 fprintf(stdout, "[%u] waiting on %d\n", getpid(), fd2);
86 xsem_wait(fd2);
87
88 fprintf(stdout, "[%u] posting 1 on %d\n", getpid(), fd1);
89 xsem_post(fd1, 1);
90
91 fprintf(stdout, "[%u] waiting on %d\n", getpid(), fd2);
92 xsem_wait(fd2);
93
94 fprintf(stdout, "[%u] posting 5 on %d\n", getpid(), fd1);
95 xsem_post(fd1, 5);
96
97 fprintf(stdout, "[%u] waiting 5 times on %d\n", getpid(), fd2);
98 xsem_wait(fd2);
99 xsem_wait(fd2);
100 xsem_wait(fd2);
101 xsem_wait(fd2);
102 xsem_wait(fd2);
103 }
104
usage(char const * prg)105 static void usage(char const *prg)
106 {
107 fprintf(stderr, "use: %s [-h]\n", prg);
108 }
109
main(int argc,char ** argv)110 int main(int argc, char **argv)
111 {
112 int c, fd1, fd2, status;
113 pid_t cpid_poster, cpid_waiter;
114
115 while ((c = getopt(argc, argv, "h")) != -1) {
116 switch (c) {
117 default:
118 usage(argv[0]);
119 return 1;
120 }
121 }
122 if ((tst_kvercmp(2, 6, 27)) < 0) {
123 tst_brkm(TCONF,
124 NULL,
125 "This test can only run on kernels that are 2.6.27 and higher");
126 }
127 if ((fd1 = eventfd2(0, EFD_SEMLIKE)) == -1 ||
128 (fd2 = eventfd2(0, EFD_SEMLIKE)) == -1) {
129 perror("eventfd2");
130 return 1;
131 }
132 if ((cpid_poster = fork()) == 0) {
133 sem_player(fd1, fd2);
134 exit(0);
135 }
136 if ((cpid_waiter = fork()) == 0) {
137 sem_player(fd2, fd1);
138 exit(0);
139 }
140 waitpid(cpid_poster, &status, 0);
141 waitpid(cpid_waiter, &status, 0);
142
143 tst_exit();
144 }
145