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 * $FreeBSD$
21 */
22
23/*
24 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
25 * Use is subject to license terms.
26 */
27
28#pragma ident	"@(#)mmapwrite.c	1.4	07/05/25 SMI"
29
30#include <unistd.h>
31#include <fcntl.h>
32#include <stdio.h>
33#include <stdlib.h>
34#include <sys/mman.h>
35#include <pthread.h>
36
37/*
38 * --------------------------------------------------------------------
39 * Bug Id: 5032643
40 *
41 * Simply writing to a file and mmaping that file at the same time can
42 * result in deadlock.  Nothing perverse like writing from the file's
43 * own mapping is required.
44 * --------------------------------------------------------------------
45 */
46
47static void *
48mapper(void *fdp)
49{
50	void *addr;
51	int fd = *(int *)fdp;
52
53	if ((addr =
54	    mmap(0, 8192, PROT_READ, MAP_SHARED, fd, 0)) == MAP_FAILED) {
55		perror("mmap");
56		exit(1);
57	}
58	for (;;) {
59		if (mmap(addr, 8192, PROT_READ,
60		    MAP_SHARED|MAP_FIXED, fd, 0) == MAP_FAILED) {
61			perror("mmap");
62			exit(1);
63		}
64	}
65	/* NOTREACHED */
66	return ((void *)1);
67}
68
69int
70main(int argc, char **argv)
71{
72	int fd;
73	char buf[BUFSIZ];
74	pthread_t pt;
75
76	if (argc != 2) {
77		(void) printf("usage: %s <file name>\n", argv[0]);
78		exit(1);
79	}
80
81	if ((fd = open(argv[1], O_RDWR|O_CREAT|O_TRUNC, 0666)) == -1) {
82		perror("open");
83		exit(1);
84	}
85
86	if (pthread_create(&pt, NULL, mapper, &fd) != 0) {
87		perror("pthread_create");
88		exit(1);
89	}
90	for (;;) {
91		if (write(fd, buf, sizeof (buf)) == -1) {
92			perror("write");
93			exit(1);
94		}
95	}
96
97	/* NOTREACHED */
98	return (0);
99}
100