xref: /titanic_44/usr/src/test/zfs-tests/cmd/mmapwrite/mmapwrite.c (revision 5fd03bc0f2e00e7ba02316c2e08f45d52aab15db)
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 *
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
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