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
prb_shmem_init(volatile shmem_msg_t ** ret_val)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
getspin(volatile shmem_msg_t * smp)84 getspin(volatile shmem_msg_t *smp)
85 {
86 return (smp->spin);
87 }
88
89 prb_status_t
prb_shmem_wait(volatile shmem_msg_t * smp)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
prb_shmem_clear(volatile shmem_msg_t * smp)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
prb_shmem_free(volatile shmem_msg_t * smp)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