2 * Copyright (c) 2017 Hans Petter Selasky
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice unmodified, this list of conditions, and the following
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.
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.
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
30 #include <sys/types.h>
31 #include <sys/malloc.h>
32 #include <sys/gtaskqueue.h>
34 #include <sys/sched.h>
36 #include <linux/compiler.h>
37 #include <linux/interrupt.h>
38 #include <linux/compat.h>
40 #define TASKLET_ST_IDLE 0
41 #define TASKLET_ST_BUSY 1
42 #define TASKLET_ST_EXEC 2
43 #define TASKLET_ST_LOOP 3
45 #define TASKLET_ST_CMPSET(ts, old, new) \
46 atomic_cmpset_int((volatile u_int *)&(ts)->tasklet_state, old, new)
48 #define TASKLET_ST_SET(ts, new) \
49 WRITE_ONCE(*(volatile u_int *)&(ts)->tasklet_state, new)
51 #define TASKLET_ST_GET(ts) \
52 READ_ONCE(*(volatile u_int *)&(ts)->tasklet_state)
54 struct tasklet_worker {
56 TAILQ_HEAD(tasklet_list, tasklet_struct) head;
57 struct grouptask gtask;
58 } __aligned(CACHE_LINE_SIZE);
60 #define TASKLET_WORKER_LOCK(tw) mtx_lock(&(tw)->mtx)
61 #define TASKLET_WORKER_UNLOCK(tw) mtx_unlock(&(tw)->mtx)
63 DPCPU_DEFINE_STATIC(struct tasklet_worker, tasklet_worker);
66 tasklet_handler(void *arg)
68 struct tasklet_worker *tw = (struct tasklet_worker *)arg;
69 struct tasklet_struct *ts;
70 struct tasklet_struct *last;
72 linux_set_current(curthread);
74 TASKLET_WORKER_LOCK(tw);
75 last = TAILQ_LAST(&tw->head, tasklet_list);
77 ts = TAILQ_FIRST(&tw->head);
80 TAILQ_REMOVE(&tw->head, ts, entry);
82 if (!atomic_read(&ts->count)) {
83 TASKLET_WORKER_UNLOCK(tw);
85 /* reset executing state */
86 TASKLET_ST_SET(ts, TASKLET_ST_EXEC);
90 } while (TASKLET_ST_CMPSET(ts, TASKLET_ST_EXEC,
91 TASKLET_ST_IDLE) == 0);
92 TASKLET_WORKER_LOCK(tw);
94 TAILQ_INSERT_TAIL(&tw->head, ts, entry);
99 TASKLET_WORKER_UNLOCK(tw);
103 tasklet_subsystem_init(void *arg __unused)
105 struct tasklet_worker *tw;
113 tw = DPCPU_ID_PTR(i, tasklet_worker);
115 mtx_init(&tw->mtx, "linux_tasklet", NULL, MTX_DEF);
116 TAILQ_INIT(&tw->head);
117 GROUPTASK_INIT(&tw->gtask, 0, tasklet_handler, tw);
118 snprintf(buf, sizeof(buf), "softirq%d", i);
119 taskqgroup_attach_cpu(qgroup_softirq, &tw->gtask,
120 "tasklet", i, NULL, NULL, buf);
123 SYSINIT(linux_tasklet, SI_SUB_TASKQ, SI_ORDER_THIRD, tasklet_subsystem_init, NULL);
126 tasklet_subsystem_uninit(void *arg __unused)
128 struct tasklet_worker *tw;
135 tw = DPCPU_ID_PTR(i, tasklet_worker);
137 taskqgroup_detach(qgroup_softirq, &tw->gtask);
138 mtx_destroy(&tw->mtx);
141 SYSUNINIT(linux_tasklet, SI_SUB_TASKQ, SI_ORDER_THIRD, tasklet_subsystem_uninit, NULL);
144 tasklet_init(struct tasklet_struct *ts,
145 tasklet_func_t *func, unsigned long data)
147 ts->entry.tqe_prev = NULL;
148 ts->entry.tqe_next = NULL;
151 atomic_set_int(&ts->tasklet_state, TASKLET_ST_IDLE);
152 atomic_set(&ts->count, 0);
156 local_bh_enable(void)
162 local_bh_disable(void)
168 tasklet_schedule(struct tasklet_struct *ts)
171 /* tasklet is paused */
172 if (atomic_read(&ts->count))
175 if (TASKLET_ST_CMPSET(ts, TASKLET_ST_EXEC, TASKLET_ST_LOOP)) {
176 /* tasklet_handler() will loop */
177 } else if (TASKLET_ST_CMPSET(ts, TASKLET_ST_IDLE, TASKLET_ST_BUSY)) {
178 struct tasklet_worker *tw;
180 tw = &DPCPU_GET(tasklet_worker);
182 /* tasklet_handler() was not queued */
183 TASKLET_WORKER_LOCK(tw);
184 /* enqueue tasklet */
185 TAILQ_INSERT_TAIL(&tw->head, ts, entry);
186 /* schedule worker */
187 GROUPTASK_ENQUEUE(&tw->gtask);
188 TASKLET_WORKER_UNLOCK(tw);
191 * tasklet_handler() is already executing
193 * If the state is neither EXEC nor IDLE, it is either
194 * LOOP or BUSY. If the state changed between the two
195 * CMPSET's above the only possible transitions by
196 * elimination are LOOP->EXEC and BUSY->EXEC. If a
197 * EXEC->LOOP transition was missed that is not a
198 * problem because the callback function is then
199 * already about to be called again.
205 tasklet_kill(struct tasklet_struct *ts)
208 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "tasklet_kill() can sleep");
210 /* wait until tasklet is no longer busy */
211 while (TASKLET_ST_GET(ts) != TASKLET_ST_IDLE)
216 tasklet_enable(struct tasklet_struct *ts)
219 atomic_dec(&ts->count);
223 tasklet_disable(struct tasklet_struct *ts)
226 atomic_inc(&ts->count);
227 tasklet_unlock_wait(ts);
231 tasklet_trylock(struct tasklet_struct *ts)
234 return (TASKLET_ST_CMPSET(ts, TASKLET_ST_IDLE, TASKLET_ST_BUSY));
238 tasklet_unlock(struct tasklet_struct *ts)
241 TASKLET_ST_SET(ts, TASKLET_ST_IDLE);
245 tasklet_unlock_wait(struct tasklet_struct *ts)
248 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "tasklet_kill() can sleep");
250 /* wait until tasklet is no longer busy */
251 while (TASKLET_ST_GET(ts) != TASKLET_ST_IDLE)