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 47 static void * 48 mapper(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 69 int 70 main(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