| 1 | /* $NetBSD: sysmon_taskq.c,v 1.19 2015/04/28 11:58:49 martin Exp $ */ |
| 2 | |
| 3 | /* |
| 4 | * Copyright (c) 2001, 2003 Wasabi Systems, Inc. |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * Written by Jason R. Thorpe for Wasabi Systems, Inc. |
| 8 | * |
| 9 | * Redistribution and use in source and binary forms, with or without |
| 10 | * modification, are permitted provided that the following conditions |
| 11 | * are met: |
| 12 | * 1. Redistributions of source code must retain the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer. |
| 14 | * 2. Redistributions in binary form must reproduce the above copyright |
| 15 | * notice, this list of conditions and the following disclaimer in the |
| 16 | * documentation and/or other materials provided with the distribution. |
| 17 | * 3. All advertising materials mentioning features or use of this software |
| 18 | * must display the following acknowledgement: |
| 19 | * This product includes software developed for the NetBSD Project by |
| 20 | * Wasabi Systems, Inc. |
| 21 | * 4. The name of Wasabi Systems, Inc. may not be used to endorse |
| 22 | * or promote products derived from this software without specific prior |
| 23 | * written permission. |
| 24 | * |
| 25 | * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND |
| 26 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
| 27 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 28 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC |
| 29 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 30 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 31 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 32 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 33 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 34 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 35 | * POSSIBILITY OF SUCH DAMAGE. |
| 36 | */ |
| 37 | |
| 38 | /* |
| 39 | * General purpose task queue for sysmon back-ends. This can be |
| 40 | * used to run callbacks that require thread context. |
| 41 | */ |
| 42 | |
| 43 | #include <sys/cdefs.h> |
| 44 | __KERNEL_RCSID(0, "$NetBSD: sysmon_taskq.c,v 1.19 2015/04/28 11:58:49 martin Exp $" ); |
| 45 | |
| 46 | #include <sys/param.h> |
| 47 | #include <sys/malloc.h> |
| 48 | #include <sys/queue.h> |
| 49 | #include <sys/proc.h> |
| 50 | #include <sys/kthread.h> |
| 51 | #include <sys/systm.h> |
| 52 | #include <sys/module.h> |
| 53 | #include <sys/once.h> |
| 54 | |
| 55 | #include <dev/sysmon/sysmon_taskq.h> |
| 56 | |
| 57 | struct sysmon_task { |
| 58 | TAILQ_ENTRY(sysmon_task) st_list; |
| 59 | void (*st_func)(void *); |
| 60 | void *st_arg; |
| 61 | u_int st_pri; |
| 62 | }; |
| 63 | |
| 64 | static TAILQ_HEAD(, sysmon_task) sysmon_task_queue = |
| 65 | TAILQ_HEAD_INITIALIZER(sysmon_task_queue); |
| 66 | |
| 67 | static kmutex_t sysmon_task_queue_mtx; |
| 68 | static kmutex_t sysmon_task_queue_init_mtx; |
| 69 | static kcondvar_t sysmon_task_queue_cv; |
| 70 | |
| 71 | static int sysmon_task_queue_initialized; |
| 72 | static int sysmon_task_queue_cleanup_sem; |
| 73 | static struct lwp *sysmon_task_queue_lwp; |
| 74 | static void sysmon_task_queue_thread(void *); |
| 75 | |
| 76 | MODULE(MODULE_CLASS_MISC, sysmon_taskq, NULL); |
| 77 | |
| 78 | /* |
| 79 | * XXX Normally, all initialization would be handled as part of |
| 80 | * the module(9) framework. However, there are a number of |
| 81 | * users of the sysmon_taskq facility that are not modular, |
| 82 | * and these can directly call sysmon_task_queue_init() |
| 83 | * directly. To accomodate these non-standard users, we |
| 84 | * make sure that sysmon_task_queue_init() handles multiple |
| 85 | * invocations. And we also ensure that, if any non-module |
| 86 | * user exists, we don't allow the module to be unloaded. |
| 87 | * (We can't use module_hold() for this, since the module(9) |
| 88 | * framework itself isn't necessarily initialized yet.) |
| 89 | */ |
| 90 | |
| 91 | /* |
| 92 | * tq_preinit: |
| 93 | * |
| 94 | * Early one-time initialization of task-queue |
| 95 | */ |
| 96 | |
| 97 | ONCE_DECL(once_tq); |
| 98 | |
| 99 | static int |
| 100 | tq_preinit(void) |
| 101 | { |
| 102 | |
| 103 | mutex_init(&sysmon_task_queue_mtx, MUTEX_DEFAULT, IPL_VM); |
| 104 | mutex_init(&sysmon_task_queue_init_mtx, MUTEX_DEFAULT, IPL_NONE); |
| 105 | cv_init(&sysmon_task_queue_cv, "smtaskq" ); |
| 106 | sysmon_task_queue_initialized = 0; |
| 107 | |
| 108 | return 0; |
| 109 | } |
| 110 | |
| 111 | /* |
| 112 | * sysmon_task_queue_init: |
| 113 | * |
| 114 | * Initialize the sysmon task queue. |
| 115 | */ |
| 116 | void |
| 117 | sysmon_task_queue_init(void) |
| 118 | { |
| 119 | int error; |
| 120 | |
| 121 | (void)RUN_ONCE(&once_tq, tq_preinit); |
| 122 | |
| 123 | mutex_enter(&sysmon_task_queue_init_mtx); |
| 124 | if (sysmon_task_queue_initialized++) { |
| 125 | mutex_exit(&sysmon_task_queue_init_mtx); |
| 126 | return; |
| 127 | } |
| 128 | |
| 129 | mutex_exit(&sysmon_task_queue_init_mtx); |
| 130 | |
| 131 | error = kthread_create(PRI_NONE, KTHREAD_MPSAFE, NULL, |
| 132 | sysmon_task_queue_thread, NULL, &sysmon_task_queue_lwp, "sysmon" ); |
| 133 | if (error) { |
| 134 | printf("Unable to create sysmon task queue thread, " |
| 135 | "error = %d\n" , error); |
| 136 | panic("sysmon_task_queue_init" ); |
| 137 | } |
| 138 | } |
| 139 | |
| 140 | /* |
| 141 | * sysmon_task_queue_fini: |
| 142 | * |
| 143 | * Tear town the sysmon task queue. |
| 144 | */ |
| 145 | int |
| 146 | sysmon_task_queue_fini(void) |
| 147 | { |
| 148 | |
| 149 | if (sysmon_task_queue_initialized > 1) |
| 150 | return EBUSY; |
| 151 | |
| 152 | mutex_enter(&sysmon_task_queue_mtx); |
| 153 | |
| 154 | sysmon_task_queue_cleanup_sem = 1; |
| 155 | cv_signal(&sysmon_task_queue_cv); |
| 156 | |
| 157 | while (sysmon_task_queue_cleanup_sem != 0) |
| 158 | cv_wait(&sysmon_task_queue_cv, |
| 159 | &sysmon_task_queue_mtx); |
| 160 | |
| 161 | mutex_exit(&sysmon_task_queue_mtx); |
| 162 | |
| 163 | return 0; |
| 164 | } |
| 165 | |
| 166 | /* |
| 167 | * sysmon_task_queue_thread: |
| 168 | * |
| 169 | * The sysmon task queue execution thread. We execute callbacks that |
| 170 | * have been queued for us. |
| 171 | */ |
| 172 | static void |
| 173 | sysmon_task_queue_thread(void *arg) |
| 174 | { |
| 175 | struct sysmon_task *st; |
| 176 | |
| 177 | /* |
| 178 | * Run through all the tasks before we check for the exit |
| 179 | * condition; it's probably more important to actually run |
| 180 | * all the tasks before we exit. |
| 181 | */ |
| 182 | mutex_enter(&sysmon_task_queue_mtx); |
| 183 | for (;;) { |
| 184 | st = TAILQ_FIRST(&sysmon_task_queue); |
| 185 | if (st != NULL) { |
| 186 | TAILQ_REMOVE(&sysmon_task_queue, st, st_list); |
| 187 | mutex_exit(&sysmon_task_queue_mtx); |
| 188 | (*st->st_func)(st->st_arg); |
| 189 | free(st, M_TEMP); |
| 190 | mutex_enter(&sysmon_task_queue_mtx); |
| 191 | } else { |
| 192 | /* Check for the exit condition. */ |
| 193 | if (sysmon_task_queue_cleanup_sem != 0) |
| 194 | break; |
| 195 | cv_wait(&sysmon_task_queue_cv, &sysmon_task_queue_mtx); |
| 196 | } |
| 197 | } |
| 198 | /* Time to die. */ |
| 199 | sysmon_task_queue_cleanup_sem = 0; |
| 200 | cv_broadcast(&sysmon_task_queue_cv); |
| 201 | mutex_exit(&sysmon_task_queue_mtx); |
| 202 | kthread_exit(0); |
| 203 | } |
| 204 | |
| 205 | /* |
| 206 | * sysmon_task_queue_sched: |
| 207 | * |
| 208 | * Schedule a task for deferred execution. |
| 209 | */ |
| 210 | int |
| 211 | sysmon_task_queue_sched(u_int pri, void (*func)(void *), void *arg) |
| 212 | { |
| 213 | struct sysmon_task *st, *lst; |
| 214 | |
| 215 | (void)RUN_ONCE(&once_tq, tq_preinit); |
| 216 | |
| 217 | if (sysmon_task_queue_lwp == NULL) |
| 218 | aprint_debug("WARNING: Callback scheduled before sysmon " |
| 219 | "task queue thread present\n" ); |
| 220 | |
| 221 | if (func == NULL) |
| 222 | return EINVAL; |
| 223 | |
| 224 | st = malloc(sizeof(*st), M_TEMP, M_NOWAIT); |
| 225 | if (st == NULL) |
| 226 | return ENOMEM; |
| 227 | |
| 228 | st->st_func = func; |
| 229 | st->st_arg = arg; |
| 230 | st->st_pri = pri; |
| 231 | |
| 232 | mutex_enter(&sysmon_task_queue_mtx); |
| 233 | TAILQ_FOREACH(lst, &sysmon_task_queue, st_list) { |
| 234 | if (st->st_pri > lst->st_pri) { |
| 235 | TAILQ_INSERT_BEFORE(lst, st, st_list); |
| 236 | break; |
| 237 | } |
| 238 | } |
| 239 | |
| 240 | if (lst == NULL) |
| 241 | TAILQ_INSERT_TAIL(&sysmon_task_queue, st, st_list); |
| 242 | |
| 243 | cv_broadcast(&sysmon_task_queue_cv); |
| 244 | mutex_exit(&sysmon_task_queue_mtx); |
| 245 | |
| 246 | return 0; |
| 247 | } |
| 248 | |
| 249 | static |
| 250 | int |
| 251 | sysmon_taskq_modcmd(modcmd_t cmd, void *arg) |
| 252 | { |
| 253 | int ret; |
| 254 | |
| 255 | switch (cmd) { |
| 256 | case MODULE_CMD_INIT: |
| 257 | sysmon_task_queue_init(); |
| 258 | ret = 0; |
| 259 | break; |
| 260 | |
| 261 | case MODULE_CMD_FINI: |
| 262 | ret = sysmon_task_queue_fini(); |
| 263 | break; |
| 264 | |
| 265 | case MODULE_CMD_STAT: |
| 266 | default: |
| 267 | ret = ENOTTY; |
| 268 | } |
| 269 | |
| 270 | return ret; |
| 271 | } |
| 272 | |