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, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright (c) 1994, by Sun Microsytems, Inc. 24 */ 25 26 #pragma ident "%Z%%M% %I% %E% SMI" 27 28 /* 29 * Interfaces to allocate, control, and free a shared memory lock 30 * XXXX Could we use a semaphore or a shared memory condition variable 31 * instead ? 32 */ 33 34 #include <unistd.h> 35 #include <fcntl.h> 36 #include <errno.h> 37 #include <stdlib.h> 38 #include <sys/mman.h> 39 #include <sys/types.h> 40 41 #include "prb_proc_int.h" 42 #include "dbg.h" 43 44 static boolean_t getspin(volatile shmem_msg_t *smp); 45 46 /* 47 * prb_shmem_init() - Allocates and initializes the shared memory region 48 */ 49 prb_status_t 50 prb_shmem_init(volatile shmem_msg_t **ret_val) 51 { 52 int shmem_fd; 53 volatile shmem_msg_t *smp; 54 55 DBG_TNF_PROBE_0(prb_shmem_init_1, "libtnfctl", "sunw%verbosity 2"); 56 57 shmem_fd = open("/dev/zero", O_RDWR); 58 if (shmem_fd == -1) { 59 DBG((void) fprintf(stderr, "couldn't open \"/dev/zero\"")); 60 return (prb_status_map(errno)); 61 } 62 /*LINTED pointer cast may result in improper alignment*/ 63 smp = (shmem_msg_t *) mmap(0, sizeof (struct shmem_msg), 64 PROT_READ | PROT_WRITE, MAP_SHARED, 65 shmem_fd, 0); 66 if (smp == (struct shmem_msg *) - 1) { 67 DBG((void) fprintf(stderr, "couldn't mmap \"/dev/zero\"")); 68 return (prb_status_map(errno)); 69 } 70 (void) close(shmem_fd); 71 72 /* sets the shared memory region to cause waiting */ 73 smp->spin = B_TRUE; 74 75 *ret_val = smp; 76 77 return (PRB_STATUS_OK); 78 } 79 80 /* 81 * prb_shmem_wait() - spins until the shared memory flag is cleared 82 */ 83 static boolean_t 84 getspin(volatile shmem_msg_t *smp) 85 { 86 return (smp->spin); 87 } 88 89 prb_status_t 90 prb_shmem_wait(volatile shmem_msg_t *smp) 91 { 92 DBG_TNF_PROBE_0(prb_shmem_wait_start, "libtnfctl", 93 "sunw%verbosity 2; start prb_shmem_wait"); 94 95 while (getspin(smp)); 96 97 DBG_TNF_PROBE_0(prb_shmem_wait_end, "libtnfctl", 98 "sunw%verbosity 2; end prb_shmem_wait"); 99 100 return (PRB_STATUS_OK); 101 102 } 103 104 105 /* 106 * prb_shmem_clear() - clears the shared memory flag and allows waiters to 107 * proceed. 108 */ 109 prb_status_t 110 prb_shmem_clear(volatile shmem_msg_t *smp) 111 { 112 DBG_TNF_PROBE_0(prb_shmem_clear_1, "libtnfctl", "sunw%verbosity 2"); 113 114 smp->spin = B_FALSE; 115 116 return (PRB_STATUS_OK); 117 } 118 119 /* 120 * prb_shmem_free() - Unmaps the shared memory region. 121 */ 122 prb_status_t 123 prb_shmem_free(volatile shmem_msg_t *smp) 124 { 125 DBG_TNF_PROBE_0(prb_shmem_free_1, "libtnfctl", "sunw%verbosity 2"); 126 127 if (munmap((caddr_t) smp, sizeof (struct shmem_msg)) != 0) { 128 DBG((void) fprintf(stderr, "couldn't munmap shared memory\n")); 129 return (prb_status_map(errno)); 130 } 131 132 return (PRB_STATUS_OK); 133 } 134