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_ptr((volatile uintptr_t *)&(ts)->entry.tqe_prev, old, new) 47 48 #define TASKLET_ST_SET(ts, new) \ 49 WRITE_ONCE(*(volatile uintptr_t *)&(ts)->entry.tqe_prev, new) 50 51 #define TASKLET_ST_GET(ts) \ 52 READ_ONCE(*(volatile uintptr_t *)&(ts)->entry.tqe_prev) 53 54 struct tasklet_worker { 55 struct mtx mtx; 56 TAILQ_HEAD(, 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 static DPCPU_DEFINE(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 71 linux_set_current(curthread); 72 73 TASKLET_WORKER_LOCK(tw); 74 while (1) { 75 ts = TAILQ_FIRST(&tw->head); 76 if (ts == NULL) 77 break; 78 TAILQ_REMOVE(&tw->head, ts, entry); 79 80 TASKLET_WORKER_UNLOCK(tw); 81 do { 82 /* reset executing state */ 83 TASKLET_ST_SET(ts, TASKLET_ST_EXEC); 84 85 ts->func(ts->data); 86 87 } while (TASKLET_ST_CMPSET(ts, TASKLET_ST_EXEC, TASKLET_ST_IDLE) == 0); 88 TASKLET_WORKER_LOCK(tw); 89 } 90 TASKLET_WORKER_UNLOCK(tw); 91 } 92 93 static void 94 tasklet_subsystem_init(void *arg __unused) 95 { 96 struct tasklet_worker *tw; 97 char buf[32]; 98 int i; 99 100 CPU_FOREACH(i) { 101 if (CPU_ABSENT(i)) 102 continue; 103 104 tw = DPCPU_ID_PTR(i, tasklet_worker); 105 106 mtx_init(&tw->mtx, "linux_tasklet", NULL, MTX_DEF); 107 TAILQ_INIT(&tw->head); 108 GROUPTASK_INIT(&tw->gtask, 0, tasklet_handler, tw); 109 snprintf(buf, sizeof(buf), "softirq%d", i); 110 taskqgroup_attach_cpu(qgroup_softirq, &tw->gtask, 111 "tasklet", i, -1, buf); 112 } 113 } 114 SYSINIT(linux_tasklet, SI_SUB_TASKQ, SI_ORDER_THIRD, tasklet_subsystem_init, NULL); 115 116 static void 117 tasklet_subsystem_uninit(void *arg __unused) 118 { 119 struct tasklet_worker *tw; 120 int i; 121 122 CPU_FOREACH(i) { 123 if (CPU_ABSENT(i)) 124 continue; 125 126 tw = DPCPU_ID_PTR(i, tasklet_worker); 127 128 taskqgroup_detach(qgroup_softirq, &tw->gtask); 129 mtx_destroy(&tw->mtx); 130 } 131 } 132 SYSUNINIT(linux_tasklet, SI_SUB_TASKQ, SI_ORDER_THIRD, tasklet_subsystem_uninit, NULL); 133 134 void 135 tasklet_init(struct tasklet_struct *ts, 136 tasklet_func_t *func, unsigned long data) 137 { 138 ts->entry.tqe_prev = NULL; 139 ts->entry.tqe_next = NULL; 140 ts->func = func; 141 ts->data = data; 142 } 143 144 void 145 local_bh_enable(void) 146 { 147 sched_unpin(); 148 } 149 150 void 151 local_bh_disable(void) 152 { 153 sched_pin(); 154 } 155 156 void 157 tasklet_schedule(struct tasklet_struct *ts) 158 { 159 160 if (TASKLET_ST_CMPSET(ts, TASKLET_ST_EXEC, TASKLET_ST_LOOP)) { 161 /* tasklet_handler() will loop */ 162 } else if (TASKLET_ST_CMPSET(ts, TASKLET_ST_IDLE, TASKLET_ST_BUSY)) { 163 struct tasklet_worker *tw; 164 165 tw = &DPCPU_GET(tasklet_worker); 166 167 /* tasklet_handler() was not queued */ 168 TASKLET_WORKER_LOCK(tw); 169 /* enqueue tasklet */ 170 TAILQ_INSERT_TAIL(&tw->head, ts, entry); 171 /* schedule worker */ 172 GROUPTASK_ENQUEUE(&tw->gtask); 173 TASKLET_WORKER_UNLOCK(tw); 174 } else { 175 /* 176 * tasklet_handler() is already executing 177 * 178 * If the state is neither EXEC nor IDLE, it is either 179 * LOOP or BUSY. If the state changed between the two 180 * CMPSET's above the only possible transitions by 181 * elimination are LOOP->EXEC and BUSY->EXEC. If a 182 * EXEC->LOOP transition was missed that is not a 183 * problem because the callback function is then 184 * already about to be called again. 185 */ 186 } 187 } 188 189 void 190 tasklet_kill(struct tasklet_struct *ts) 191 { 192 193 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "tasklet_kill() can sleep"); 194 195 /* wait until tasklet is no longer busy */ 196 while (TASKLET_ST_GET(ts) != TASKLET_ST_IDLE) 197 pause("W", 1); 198 } 199