1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2007 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #include <unistd.h>
28 #include <fcntl.h>
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <sys/mman.h>
32 #include <pthread.h>
33
34 /*
35 * --------------------------------------------------------------------
36 * Bug Id: 5032643
37 *
38 * Simply writing to a file and mmaping that file at the same time can
39 * result in deadlock. Nothing perverse like writing from the file's
40 * own mapping is required.
41 * --------------------------------------------------------------------
42 */
43
44 static void *
mapper(void * fdp)45 mapper(void *fdp)
46 {
47 void *addr;
48 int fd = *(int *)fdp;
49
50 if ((addr =
51 mmap(0, 8192, PROT_READ, MAP_SHARED, fd, 0)) == MAP_FAILED) {
52 perror("mmap");
53 exit(1);
54 }
55 for (;;) {
56 if (mmap(addr, 8192, PROT_READ,
57 MAP_SHARED|MAP_FIXED, fd, 0) == MAP_FAILED) {
58 perror("mmap");
59 exit(1);
60 }
61 }
62 /* NOTREACHED */
63 return ((void *)1);
64 }
65
66 int
main(int argc,char ** argv)67 main(int argc, char **argv)
68 {
69 int fd;
70 char buf[BUFSIZ];
71
72 if (argc != 2) {
73 (void) printf("usage: %s <file name>\n", argv[0]);
74 exit(1);
75 }
76
77 if ((fd = open(argv[1], O_RDWR|O_CREAT|O_TRUNC, 0666)) == -1) {
78 perror("open");
79 exit(1);
80 }
81
82 if (pthread_create(NULL, NULL, mapper, &fd) != 0) {
83 perror("pthread_create");
84 exit(1);
85 }
86 for (;;) {
87 if (write(fd, buf, sizeof (buf)) == -1) {
88 perror("write");
89 exit(1);
90 }
91 }
92
93 /* NOTREACHED */
94 return (0);
95 }
96