1 /*- 2 * Copyright (c) 2017 Hans Petter Selasky 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include <sys/types.h> 31 #include <sys/malloc.h> 32 #include <sys/gtaskqueue.h> 33 #include <sys/proc.h> 34 #include <sys/sched.h> 35 36 #include <linux/compiler.h> 37 #include <linux/interrupt.h> 38 #include <linux/compat.h> 39 40 #define TASKLET_ST_IDLE 0 41 #define TASKLET_ST_BUSY 1 42 #define TASKLET_ST_EXEC 2 43 #define TASKLET_ST_LOOP 3 44 45 #define TASKLET_ST_CMPSET(ts, old, new) \ 46 atomic_cmpset_int((volatile u_int *)&(ts)->tasklet_state, old, new) 47 48 #define TASKLET_ST_SET(ts, new) \ 49 WRITE_ONCE(*(volatile u_int *)&(ts)->tasklet_state, new) 50 51 #define TASKLET_ST_GET(ts) \ 52 READ_ONCE(*(volatile u_int *)&(ts)->tasklet_state) 53 54 struct tasklet_worker { 55 struct mtx mtx; 56 TAILQ_HEAD(tasklet_list, tasklet_struct) head; 57 struct grouptask gtask; 58 } __aligned(CACHE_LINE_SIZE); 59 60 #define TASKLET_WORKER_LOCK(tw) mtx_lock(&(tw)->mtx) 61 #define TASKLET_WORKER_UNLOCK(tw) mtx_unlock(&(tw)->mtx) 62 63 DPCPU_DEFINE_STATIC(struct tasklet_worker, tasklet_worker); 64 65 static void 66 tasklet_handler(void *arg) 67 { 68 struct tasklet_worker *tw = (struct tasklet_worker *)arg; 69 struct tasklet_struct *ts; 70 struct tasklet_struct *last; 71 72 linux_set_current(curthread); 73 74 TASKLET_WORKER_LOCK(tw); 75 last = TAILQ_LAST(&tw->head, tasklet_list); 76 while (1) { 77 ts = TAILQ_FIRST(&tw->head); 78 if (ts == NULL) 79 break; 80 TAILQ_REMOVE(&tw->head, ts, entry); 81 82 if (!atomic_read(&ts->count)) { 83 TASKLET_WORKER_UNLOCK(tw); 84 do { 85 /* reset executing state */ 86 TASKLET_ST_SET(ts, TASKLET_ST_EXEC); 87 88 if (ts->use_callback) 89 ts->callback(ts); 90 else 91 ts->func(ts->data); 92 93 } while (TASKLET_ST_CMPSET(ts, TASKLET_ST_EXEC, 94 TASKLET_ST_IDLE) == 0); 95 TASKLET_WORKER_LOCK(tw); 96 } else { 97 TAILQ_INSERT_TAIL(&tw->head, ts, entry); 98 } 99 if (ts == last) 100 break; 101 } 102 TASKLET_WORKER_UNLOCK(tw); 103 } 104 105 static void 106 tasklet_subsystem_init(void *arg __unused) 107 { 108 struct tasklet_worker *tw; 109 char buf[32]; 110 int i; 111 112 CPU_FOREACH(i) { 113 if (CPU_ABSENT(i)) 114 continue; 115 116 tw = DPCPU_ID_PTR(i, tasklet_worker); 117 118 mtx_init(&tw->mtx, "linux_tasklet", NULL, MTX_DEF); 119 TAILQ_INIT(&tw->head); 120 GROUPTASK_INIT(&tw->gtask, 0, tasklet_handler, tw); 121 snprintf(buf, sizeof(buf), "softirq%d", i); 122 taskqgroup_attach_cpu(qgroup_softirq, &tw->gtask, 123 "tasklet", i, NULL, NULL, buf); 124 } 125 } 126 SYSINIT(linux_tasklet, SI_SUB_TASKQ, SI_ORDER_THIRD, tasklet_subsystem_init, NULL); 127 128 static void 129 tasklet_subsystem_uninit(void *arg __unused) 130 { 131 struct tasklet_worker *tw; 132 int i; 133 134 taskqgroup_drain_all(qgroup_softirq); 135 136 CPU_FOREACH(i) { 137 if (CPU_ABSENT(i)) 138 continue; 139 140 tw = DPCPU_ID_PTR(i, tasklet_worker); 141 142 taskqgroup_detach(qgroup_softirq, &tw->gtask); 143 mtx_destroy(&tw->mtx); 144 } 145 } 146 SYSUNINIT(linux_tasklet, SI_SUB_TASKQ, SI_ORDER_THIRD, tasklet_subsystem_uninit, NULL); 147 148 void 149 tasklet_init(struct tasklet_struct *ts, 150 tasklet_func_t *func, unsigned long data) 151 { 152 ts->entry.tqe_prev = NULL; 153 ts->entry.tqe_next = NULL; 154 ts->func = func; 155 ts->callback = NULL; 156 ts->data = data; 157 atomic_set_int(&ts->tasklet_state, TASKLET_ST_IDLE); 158 atomic_set(&ts->count, 0); 159 ts->use_callback = false; 160 } 161 162 void 163 tasklet_setup(struct tasklet_struct *ts, tasklet_callback_t *c) 164 { 165 ts->entry.tqe_prev = NULL; 166 ts->entry.tqe_next = NULL; 167 ts->func = NULL; 168 ts->callback = c; 169 ts->data = 0; 170 atomic_set_int(&ts->tasklet_state, TASKLET_ST_IDLE); 171 atomic_set(&ts->count, 0); 172 ts->use_callback = true; 173 } 174 175 void 176 local_bh_enable(void) 177 { 178 sched_unpin(); 179 } 180 181 void 182 local_bh_disable(void) 183 { 184 sched_pin(); 185 } 186 187 void 188 tasklet_schedule(struct tasklet_struct *ts) 189 { 190 191 /* tasklet is paused */ 192 if (atomic_read(&ts->count)) 193 return; 194 195 if (TASKLET_ST_CMPSET(ts, TASKLET_ST_EXEC, TASKLET_ST_LOOP)) { 196 /* tasklet_handler() will loop */ 197 } else if (TASKLET_ST_CMPSET(ts, TASKLET_ST_IDLE, TASKLET_ST_BUSY)) { 198 struct tasklet_worker *tw; 199 200 tw = &DPCPU_GET(tasklet_worker); 201 202 /* tasklet_handler() was not queued */ 203 TASKLET_WORKER_LOCK(tw); 204 /* enqueue tasklet */ 205 TAILQ_INSERT_TAIL(&tw->head, ts, entry); 206 /* schedule worker */ 207 GROUPTASK_ENQUEUE(&tw->gtask); 208 TASKLET_WORKER_UNLOCK(tw); 209 } else { 210 /* 211 * tasklet_handler() is already executing 212 * 213 * If the state is neither EXEC nor IDLE, it is either 214 * LOOP or BUSY. If the state changed between the two 215 * CMPSET's above the only possible transitions by 216 * elimination are LOOP->EXEC and BUSY->EXEC. If a 217 * EXEC->LOOP transition was missed that is not a 218 * problem because the callback function is then 219 * already about to be called again. 220 */ 221 } 222 } 223 224 void 225 tasklet_kill(struct tasklet_struct *ts) 226 { 227 228 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "tasklet_kill() can sleep"); 229 230 /* wait until tasklet is no longer busy */ 231 while (TASKLET_ST_GET(ts) != TASKLET_ST_IDLE) 232 pause("W", 1); 233 } 234 235 void 236 tasklet_enable(struct tasklet_struct *ts) 237 { 238 239 atomic_dec(&ts->count); 240 } 241 242 void 243 tasklet_disable(struct tasklet_struct *ts) 244 { 245 246 atomic_inc(&ts->count); 247 tasklet_unlock_wait(ts); 248 } 249 250 void 251 tasklet_disable_nosync(struct tasklet_struct *ts) 252 { 253 atomic_inc(&ts->count); 254 barrier(); 255 } 256 257 int 258 tasklet_trylock(struct tasklet_struct *ts) 259 { 260 261 return (TASKLET_ST_CMPSET(ts, TASKLET_ST_IDLE, TASKLET_ST_BUSY)); 262 } 263 264 void 265 tasklet_unlock(struct tasklet_struct *ts) 266 { 267 268 TASKLET_ST_SET(ts, TASKLET_ST_IDLE); 269 } 270 271 void 272 tasklet_unlock_wait(struct tasklet_struct *ts) 273 { 274 275 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "tasklet_kill() can sleep"); 276 277 /* wait until tasklet is no longer busy */ 278 while (TASKLET_ST_GET(ts) != TASKLET_ST_IDLE) 279 pause("W", 1); 280 } 281