xref: /freebsd/sys/compat/linuxkpi/common/src/linux_rcu.c (revision 6ae240797f8b497f802b4380a28ddbaf9048ca74)
11a01b4e5SHans Petter Selasky /*-
296fc97c8SStephen Hurd  * Copyright (c) 2016 Matthew Macy (mmacy@mattmacy.io)
3eae5868cSHans Petter Selasky  * Copyright (c) 2017-2020 Hans Petter Selasky (hselasky@freebsd.org)
41a01b4e5SHans Petter Selasky  * All rights reserved.
51a01b4e5SHans Petter Selasky  *
61a01b4e5SHans Petter Selasky  * Redistribution and use in source and binary forms, with or without
71a01b4e5SHans Petter Selasky  * modification, are permitted provided that the following conditions
81a01b4e5SHans Petter Selasky  * are met:
91a01b4e5SHans Petter Selasky  * 1. Redistributions of source code must retain the above copyright
101a01b4e5SHans Petter Selasky  *    notice unmodified, this list of conditions, and the following
111a01b4e5SHans Petter Selasky  *    disclaimer.
121a01b4e5SHans Petter Selasky  * 2. Redistributions in binary form must reproduce the above copyright
131a01b4e5SHans Petter Selasky  *    notice, this list of conditions and the following disclaimer in the
141a01b4e5SHans Petter Selasky  *    documentation and/or other materials provided with the distribution.
151a01b4e5SHans Petter Selasky  *
161a01b4e5SHans Petter Selasky  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
171a01b4e5SHans Petter Selasky  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
181a01b4e5SHans Petter Selasky  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
191a01b4e5SHans Petter Selasky  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
201a01b4e5SHans Petter Selasky  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
211a01b4e5SHans Petter Selasky  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
221a01b4e5SHans Petter Selasky  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
231a01b4e5SHans Petter Selasky  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
241a01b4e5SHans Petter Selasky  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
251a01b4e5SHans Petter Selasky  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
261a01b4e5SHans Petter Selasky  */
271a01b4e5SHans Petter Selasky 
281a01b4e5SHans Petter Selasky #include <sys/cdefs.h>
291a01b4e5SHans Petter Selasky __FBSDID("$FreeBSD$");
301a01b4e5SHans Petter Selasky 
311a01b4e5SHans Petter Selasky #include <sys/types.h>
321a01b4e5SHans Petter Selasky #include <sys/systm.h>
331a01b4e5SHans Petter Selasky #include <sys/malloc.h>
341a01b4e5SHans Petter Selasky #include <sys/kernel.h>
351a01b4e5SHans Petter Selasky #include <sys/lock.h>
361a01b4e5SHans Petter Selasky #include <sys/mutex.h>
371a01b4e5SHans Petter Selasky #include <sys/proc.h>
381a01b4e5SHans Petter Selasky #include <sys/sched.h>
391a01b4e5SHans Petter Selasky #include <sys/smp.h>
401a01b4e5SHans Petter Selasky #include <sys/queue.h>
411a01b4e5SHans Petter Selasky #include <sys/taskqueue.h>
42f3de9af6SHans Petter Selasky #include <sys/kdb.h>
431a01b4e5SHans Petter Selasky 
441a01b4e5SHans Petter Selasky #include <ck_epoch.h>
451a01b4e5SHans Petter Selasky 
461a01b4e5SHans Petter Selasky #include <linux/rcupdate.h>
471a01b4e5SHans Petter Selasky #include <linux/srcu.h>
481a01b4e5SHans Petter Selasky #include <linux/slab.h>
491a01b4e5SHans Petter Selasky #include <linux/kernel.h>
50f3de9af6SHans Petter Selasky #include <linux/compat.h>
511a01b4e5SHans Petter Selasky 
52f3de9af6SHans Petter Selasky /*
53f3de9af6SHans Petter Selasky  * By defining CONFIG_NO_RCU_SKIP LinuxKPI RCU locks and asserts will
54f3de9af6SHans Petter Selasky  * not be skipped during panic().
55f3de9af6SHans Petter Selasky  */
56f3de9af6SHans Petter Selasky #ifdef CONFIG_NO_RCU_SKIP
57f3de9af6SHans Petter Selasky #define	RCU_SKIP(void) 0
58f3de9af6SHans Petter Selasky #else
59f3de9af6SHans Petter Selasky #define	RCU_SKIP(void)	unlikely(SCHEDULER_STOPPED() || kdb_active)
60f3de9af6SHans Petter Selasky #endif
611f827dabSHans Petter Selasky 
621f827dabSHans Petter Selasky struct callback_head {
631f827dabSHans Petter Selasky 	STAILQ_ENTRY(callback_head) entry;
641f827dabSHans Petter Selasky 	rcu_callback_t func;
651f827dabSHans Petter Selasky };
661f827dabSHans Petter Selasky 
67f3de9af6SHans Petter Selasky struct linux_epoch_head {
68f3de9af6SHans Petter Selasky 	STAILQ_HEAD(, callback_head) cb_head;
69f3de9af6SHans Petter Selasky 	struct mtx lock;
70f3de9af6SHans Petter Selasky 	struct task task;
71f3de9af6SHans Petter Selasky } __aligned(CACHE_LINE_SIZE);
72f3de9af6SHans Petter Selasky 
73f3de9af6SHans Petter Selasky struct linux_epoch_record {
741f827dabSHans Petter Selasky 	ck_epoch_record_t epoch_record;
75f3de9af6SHans Petter Selasky 	TAILQ_HEAD(, task_struct) ts_head;
76f3de9af6SHans Petter Selasky 	int cpuid;
77*6ae24079SHans Petter Selasky 	int type;
78f3de9af6SHans Petter Selasky } __aligned(CACHE_LINE_SIZE);
791a01b4e5SHans Petter Selasky 
801a01b4e5SHans Petter Selasky /*
811a01b4e5SHans Petter Selasky  * Verify that "struct rcu_head" is big enough to hold "struct
821a01b4e5SHans Petter Selasky  * callback_head". This has been done to avoid having to add special
831a01b4e5SHans Petter Selasky  * compile flags for including ck_epoch.h to all clients of the
841a01b4e5SHans Petter Selasky  * LinuxKPI.
851a01b4e5SHans Petter Selasky  */
86f3de9af6SHans Petter Selasky CTASSERT(sizeof(struct rcu_head) == sizeof(struct callback_head));
871a01b4e5SHans Petter Selasky 
881f827dabSHans Petter Selasky /*
891f827dabSHans Petter Selasky  * Verify that "epoch_record" is at beginning of "struct
90f3de9af6SHans Petter Selasky  * linux_epoch_record":
911f827dabSHans Petter Selasky  */
92f3de9af6SHans Petter Selasky CTASSERT(offsetof(struct linux_epoch_record, epoch_record) == 0);
931f827dabSHans Petter Selasky 
94*6ae24079SHans Petter Selasky CTASSERT(TS_RCU_TYPE_MAX == RCU_TYPE_MAX);
95*6ae24079SHans Petter Selasky 
96eae5868cSHans Petter Selasky static ck_epoch_t linux_epoch[RCU_TYPE_MAX];
97eae5868cSHans Petter Selasky static struct linux_epoch_head linux_epoch_head[RCU_TYPE_MAX];
98eae5868cSHans Petter Selasky DPCPU_DEFINE_STATIC(struct linux_epoch_record, linux_epoch_record[RCU_TYPE_MAX]);
991f827dabSHans Petter Selasky 
1001f827dabSHans Petter Selasky static void linux_rcu_cleaner_func(void *, int);
1011a01b4e5SHans Petter Selasky 
1021a01b4e5SHans Petter Selasky static void
1031a01b4e5SHans Petter Selasky linux_rcu_runtime_init(void *arg __unused)
1041a01b4e5SHans Petter Selasky {
105f3de9af6SHans Petter Selasky 	struct linux_epoch_head *head;
1061a01b4e5SHans Petter Selasky 	int i;
107eae5868cSHans Petter Selasky 	int j;
1081a01b4e5SHans Petter Selasky 
109eae5868cSHans Petter Selasky 	for (j = 0; j != RCU_TYPE_MAX; j++) {
110eae5868cSHans Petter Selasky 		ck_epoch_init(&linux_epoch[j]);
1111a01b4e5SHans Petter Selasky 
112eae5868cSHans Petter Selasky 		head = &linux_epoch_head[j];
113f3de9af6SHans Petter Selasky 
114f3de9af6SHans Petter Selasky 		mtx_init(&head->lock, "LRCU-HEAD", NULL, MTX_DEF);
115eae5868cSHans Petter Selasky 		TASK_INIT(&head->task, 0, linux_rcu_cleaner_func, head);
116f3de9af6SHans Petter Selasky 		STAILQ_INIT(&head->cb_head);
117f3de9af6SHans Petter Selasky 
1181a01b4e5SHans Petter Selasky 		CPU_FOREACH(i) {
119f3de9af6SHans Petter Selasky 			struct linux_epoch_record *record;
1201f827dabSHans Petter Selasky 
121eae5868cSHans Petter Selasky 			record = &DPCPU_ID_GET(i, linux_epoch_record[j]);
1221f827dabSHans Petter Selasky 
123f3de9af6SHans Petter Selasky 			record->cpuid = i;
124*6ae24079SHans Petter Selasky 			record->type = j;
125eae5868cSHans Petter Selasky 			ck_epoch_register(&linux_epoch[j],
126eae5868cSHans Petter Selasky 			    &record->epoch_record, NULL);
127f3de9af6SHans Petter Selasky 			TAILQ_INIT(&record->ts_head);
1281a01b4e5SHans Petter Selasky 		}
1291a01b4e5SHans Petter Selasky 	}
130eae5868cSHans Petter Selasky }
131d8e073a9SHans Petter Selasky SYSINIT(linux_rcu_runtime, SI_SUB_CPU, SI_ORDER_ANY, linux_rcu_runtime_init, NULL);
1321a01b4e5SHans Petter Selasky 
1331a01b4e5SHans Petter Selasky static void
1341a01b4e5SHans Petter Selasky linux_rcu_runtime_uninit(void *arg __unused)
1351a01b4e5SHans Petter Selasky {
136f3de9af6SHans Petter Selasky 	struct linux_epoch_head *head;
137eae5868cSHans Petter Selasky 	int j;
1381a01b4e5SHans Petter Selasky 
139eae5868cSHans Petter Selasky 	for (j = 0; j != RCU_TYPE_MAX; j++) {
140eae5868cSHans Petter Selasky 		head = &linux_epoch_head[j];
1411a01b4e5SHans Petter Selasky 
142f3de9af6SHans Petter Selasky 		mtx_destroy(&head->lock);
1431a01b4e5SHans Petter Selasky 	}
144eae5868cSHans Petter Selasky }
1451a01b4e5SHans Petter Selasky SYSUNINIT(linux_rcu_runtime, SI_SUB_LOCK, SI_ORDER_SECOND, linux_rcu_runtime_uninit, NULL);
1461a01b4e5SHans Petter Selasky 
1471f827dabSHans Petter Selasky static void
148eae5868cSHans Petter Selasky linux_rcu_cleaner_func(void *context, int pending __unused)
1491f827dabSHans Petter Selasky {
150f3de9af6SHans Petter Selasky 	struct linux_epoch_head *head;
1511a01b4e5SHans Petter Selasky 	struct callback_head *rcu;
152f3de9af6SHans Petter Selasky 	STAILQ_HEAD(, callback_head) tmp_head;
153eae5868cSHans Petter Selasky 	uintptr_t offset;
1541f827dabSHans Petter Selasky 
155f3de9af6SHans Petter Selasky 	linux_set_current(curthread);
156f3de9af6SHans Petter Selasky 
157eae5868cSHans Petter Selasky 	head = context;
1581f827dabSHans Petter Selasky 
1591f827dabSHans Petter Selasky 	/* move current callbacks into own queue */
160f3de9af6SHans Petter Selasky 	mtx_lock(&head->lock);
161f3de9af6SHans Petter Selasky 	STAILQ_INIT(&tmp_head);
162f3de9af6SHans Petter Selasky 	STAILQ_CONCAT(&tmp_head, &head->cb_head);
163f3de9af6SHans Petter Selasky 	mtx_unlock(&head->lock);
1641f827dabSHans Petter Selasky 
1651f827dabSHans Petter Selasky 	/* synchronize */
166eae5868cSHans Petter Selasky 	linux_synchronize_rcu(head - linux_epoch_head);
1671f827dabSHans Petter Selasky 
1681f827dabSHans Petter Selasky 	/* dispatch all callbacks, if any */
169f3de9af6SHans Petter Selasky 	while ((rcu = STAILQ_FIRST(&tmp_head)) != NULL) {
1701a01b4e5SHans Petter Selasky 
171f3de9af6SHans Petter Selasky 		STAILQ_REMOVE_HEAD(&tmp_head, entry);
1721a01b4e5SHans Petter Selasky 
1731a01b4e5SHans Petter Selasky 		offset = (uintptr_t)rcu->func;
1741a01b4e5SHans Petter Selasky 
1751a01b4e5SHans Petter Selasky 		if (offset < LINUX_KFREE_RCU_OFFSET_MAX)
1761a01b4e5SHans Petter Selasky 			kfree((char *)rcu - offset);
1771a01b4e5SHans Petter Selasky 		else
1781a01b4e5SHans Petter Selasky 			rcu->func((struct rcu_head *)rcu);
1791a01b4e5SHans Petter Selasky 	}
1801a01b4e5SHans Petter Selasky }
1811a01b4e5SHans Petter Selasky 
1821a01b4e5SHans Petter Selasky void
183eae5868cSHans Petter Selasky linux_rcu_read_lock(unsigned type)
1841a01b4e5SHans Petter Selasky {
185f3de9af6SHans Petter Selasky 	struct linux_epoch_record *record;
186f3de9af6SHans Petter Selasky 	struct task_struct *ts;
187f3de9af6SHans Petter Selasky 
188eae5868cSHans Petter Selasky 	MPASS(type < RCU_TYPE_MAX);
189eae5868cSHans Petter Selasky 
190f3de9af6SHans Petter Selasky 	if (RCU_SKIP())
191f3de9af6SHans Petter Selasky 		return;
1921a01b4e5SHans Petter Selasky 
1931f827dabSHans Petter Selasky 	/*
1941f827dabSHans Petter Selasky 	 * Pin thread to current CPU so that the unlock code gets the
195f3de9af6SHans Petter Selasky 	 * same per-CPU epoch record:
1961f827dabSHans Petter Selasky 	 */
1971a01b4e5SHans Petter Selasky 	sched_pin();
1981a01b4e5SHans Petter Selasky 
199eae5868cSHans Petter Selasky 	record = &DPCPU_GET(linux_epoch_record[type]);
200f3de9af6SHans Petter Selasky 	ts = current;
2011f827dabSHans Petter Selasky 
2021f827dabSHans Petter Selasky 	/*
2031f827dabSHans Petter Selasky 	 * Use a critical section to prevent recursion inside
2041f827dabSHans Petter Selasky 	 * ck_epoch_begin(). Else this function supports recursion.
2051f827dabSHans Petter Selasky 	 */
2061f827dabSHans Petter Selasky 	critical_enter();
207f3de9af6SHans Petter Selasky 	ck_epoch_begin(&record->epoch_record, NULL);
208*6ae24079SHans Petter Selasky 	ts->rcu_recurse[type]++;
209*6ae24079SHans Petter Selasky 	if (ts->rcu_recurse[type] == 1)
210*6ae24079SHans Petter Selasky 		TAILQ_INSERT_TAIL(&record->ts_head, ts, rcu_entry[type]);
2111f827dabSHans Petter Selasky 	critical_exit();
2121a01b4e5SHans Petter Selasky }
2131a01b4e5SHans Petter Selasky 
2141a01b4e5SHans Petter Selasky void
215eae5868cSHans Petter Selasky linux_rcu_read_unlock(unsigned type)
2161a01b4e5SHans Petter Selasky {
217f3de9af6SHans Petter Selasky 	struct linux_epoch_record *record;
218f3de9af6SHans Petter Selasky 	struct task_struct *ts;
2191a01b4e5SHans Petter Selasky 
220eae5868cSHans Petter Selasky 	MPASS(type < RCU_TYPE_MAX);
221eae5868cSHans Petter Selasky 
222f3de9af6SHans Petter Selasky 	if (RCU_SKIP())
223f3de9af6SHans Petter Selasky 		return;
224f3de9af6SHans Petter Selasky 
225eae5868cSHans Petter Selasky 	record = &DPCPU_GET(linux_epoch_record[type]);
226f3de9af6SHans Petter Selasky 	ts = current;
2271f827dabSHans Petter Selasky 
2281f827dabSHans Petter Selasky 	/*
2291f827dabSHans Petter Selasky 	 * Use a critical section to prevent recursion inside
2301f827dabSHans Petter Selasky 	 * ck_epoch_end(). Else this function supports recursion.
2311f827dabSHans Petter Selasky 	 */
2321f827dabSHans Petter Selasky 	critical_enter();
233f3de9af6SHans Petter Selasky 	ck_epoch_end(&record->epoch_record, NULL);
234*6ae24079SHans Petter Selasky 	ts->rcu_recurse[type]--;
235*6ae24079SHans Petter Selasky 	if (ts->rcu_recurse[type] == 0)
236*6ae24079SHans Petter Selasky 		TAILQ_REMOVE(&record->ts_head, ts, rcu_entry[type]);
2371f827dabSHans Petter Selasky 	critical_exit();
2381f827dabSHans Petter Selasky 
2391a01b4e5SHans Petter Selasky 	sched_unpin();
2401a01b4e5SHans Petter Selasky }
2411a01b4e5SHans Petter Selasky 
242f3de9af6SHans Petter Selasky static void
243f3de9af6SHans Petter Selasky linux_synchronize_rcu_cb(ck_epoch_t *epoch __unused, ck_epoch_record_t *epoch_record, void *arg __unused)
244f3de9af6SHans Petter Selasky {
245f3de9af6SHans Petter Selasky 	struct linux_epoch_record *record =
246f3de9af6SHans Petter Selasky 	    container_of(epoch_record, struct linux_epoch_record, epoch_record);
247f3de9af6SHans Petter Selasky 	struct thread *td = curthread;
248f3de9af6SHans Petter Selasky 	struct task_struct *ts;
249f3de9af6SHans Petter Selasky 
250f3de9af6SHans Petter Selasky 	/* check if blocked on the current CPU */
251f3de9af6SHans Petter Selasky 	if (record->cpuid == PCPU_GET(cpuid)) {
252f3de9af6SHans Petter Selasky 		bool is_sleeping = 0;
253f3de9af6SHans Petter Selasky 		u_char prio = 0;
254f3de9af6SHans Petter Selasky 
255f3de9af6SHans Petter Selasky 		/*
256f3de9af6SHans Petter Selasky 		 * Find the lowest priority or sleeping thread which
257f3de9af6SHans Petter Selasky 		 * is blocking synchronization on this CPU core. All
258f3de9af6SHans Petter Selasky 		 * the threads in the queue are CPU-pinned and cannot
259f3de9af6SHans Petter Selasky 		 * go anywhere while the current thread is locked.
260f3de9af6SHans Petter Selasky 		 */
261*6ae24079SHans Petter Selasky 		TAILQ_FOREACH(ts, &record->ts_head, rcu_entry[record->type]) {
262f3de9af6SHans Petter Selasky 			if (ts->task_thread->td_priority > prio)
263f3de9af6SHans Petter Selasky 				prio = ts->task_thread->td_priority;
264f3de9af6SHans Petter Selasky 			is_sleeping |= (ts->task_thread->td_inhibitors != 0);
265f3de9af6SHans Petter Selasky 		}
266f3de9af6SHans Petter Selasky 
267f3de9af6SHans Petter Selasky 		if (is_sleeping) {
268f3de9af6SHans Petter Selasky 			thread_unlock(td);
269f3de9af6SHans Petter Selasky 			pause("W", 1);
270f3de9af6SHans Petter Selasky 			thread_lock(td);
271f3de9af6SHans Petter Selasky 		} else {
272f3de9af6SHans Petter Selasky 			/* set new thread priority */
273f3de9af6SHans Petter Selasky 			sched_prio(td, prio);
274f3de9af6SHans Petter Selasky 			/* task switch */
275686bcb5cSJeff Roberson 			mi_switch(SW_VOL | SWT_RELINQUISH);
276cc79ea3aSHans Petter Selasky 			/*
277cc79ea3aSHans Petter Selasky 			 * It is important the thread lock is dropped
278cc79ea3aSHans Petter Selasky 			 * while yielding to allow other threads to
279cc79ea3aSHans Petter Selasky 			 * acquire the lock pointed to by
280cc79ea3aSHans Petter Selasky 			 * TDQ_LOCKPTR(td). Currently mi_switch() will
281cc79ea3aSHans Petter Selasky 			 * unlock the thread lock before
282cc79ea3aSHans Petter Selasky 			 * returning. Else a deadlock like situation
283cc79ea3aSHans Petter Selasky 			 * might happen.
284cc79ea3aSHans Petter Selasky 			 */
285714ed5b2SHans Petter Selasky 			thread_lock(td);
286f3de9af6SHans Petter Selasky 		}
287f3de9af6SHans Petter Selasky 	} else {
288f3de9af6SHans Petter Selasky 		/*
289f3de9af6SHans Petter Selasky 		 * To avoid spinning move execution to the other CPU
290f3de9af6SHans Petter Selasky 		 * which is blocking synchronization. Set highest
291f3de9af6SHans Petter Selasky 		 * thread priority so that code gets run. The thread
292f3de9af6SHans Petter Selasky 		 * priority will be restored later.
293f3de9af6SHans Petter Selasky 		 */
294f3de9af6SHans Petter Selasky 		sched_prio(td, 0);
295f3de9af6SHans Petter Selasky 		sched_bind(td, record->cpuid);
296f3de9af6SHans Petter Selasky 	}
297f3de9af6SHans Petter Selasky }
298f3de9af6SHans Petter Selasky 
2991a01b4e5SHans Petter Selasky void
300eae5868cSHans Petter Selasky linux_synchronize_rcu(unsigned type)
3011a01b4e5SHans Petter Selasky {
302f3de9af6SHans Petter Selasky 	struct thread *td;
303f3de9af6SHans Petter Selasky 	int was_bound;
304f3de9af6SHans Petter Selasky 	int old_cpu;
305f3de9af6SHans Petter Selasky 	int old_pinned;
3063f743d78SHans Petter Selasky 	u_char old_prio;
307f3de9af6SHans Petter Selasky 
308eae5868cSHans Petter Selasky 	MPASS(type < RCU_TYPE_MAX);
309eae5868cSHans Petter Selasky 
310f3de9af6SHans Petter Selasky 	if (RCU_SKIP())
311f3de9af6SHans Petter Selasky 		return;
312f3de9af6SHans Petter Selasky 
313f3de9af6SHans Petter Selasky 	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
314f3de9af6SHans Petter Selasky 	    "linux_synchronize_rcu() can sleep");
315f3de9af6SHans Petter Selasky 
316f3de9af6SHans Petter Selasky 	td = curthread;
317fedab1b4SKonstantin Belousov 	DROP_GIANT();
318f3de9af6SHans Petter Selasky 
319f3de9af6SHans Petter Selasky 	/*
320f3de9af6SHans Petter Selasky 	 * Synchronizing RCU might change the CPU core this function
321f3de9af6SHans Petter Selasky 	 * is running on. Save current values:
322f3de9af6SHans Petter Selasky 	 */
323f3de9af6SHans Petter Selasky 	thread_lock(td);
324f3de9af6SHans Petter Selasky 
325f3de9af6SHans Petter Selasky 	old_cpu = PCPU_GET(cpuid);
326f3de9af6SHans Petter Selasky 	old_pinned = td->td_pinned;
3273f743d78SHans Petter Selasky 	old_prio = td->td_priority;
328f3de9af6SHans Petter Selasky 	was_bound = sched_is_bound(td);
329ea165254SHans Petter Selasky 	sched_unbind(td);
330ea165254SHans Petter Selasky 	td->td_pinned = 0;
331f3de9af6SHans Petter Selasky 	sched_bind(td, old_cpu);
332f3de9af6SHans Petter Selasky 
333eae5868cSHans Petter Selasky 	ck_epoch_synchronize_wait(&linux_epoch[type],
334f3de9af6SHans Petter Selasky 	    &linux_synchronize_rcu_cb, NULL);
335f3de9af6SHans Petter Selasky 
336f3de9af6SHans Petter Selasky 	/* restore CPU binding, if any */
337f3de9af6SHans Petter Selasky 	if (was_bound != 0) {
338f3de9af6SHans Petter Selasky 		sched_bind(td, old_cpu);
339f3de9af6SHans Petter Selasky 	} else {
340f3de9af6SHans Petter Selasky 		/* get thread back to initial CPU, if any */
341f3de9af6SHans Petter Selasky 		if (old_pinned != 0)
342f3de9af6SHans Petter Selasky 			sched_bind(td, old_cpu);
343f3de9af6SHans Petter Selasky 		sched_unbind(td);
344f3de9af6SHans Petter Selasky 	}
345f3de9af6SHans Petter Selasky 	/* restore pinned after bind */
346f3de9af6SHans Petter Selasky 	td->td_pinned = old_pinned;
3473f743d78SHans Petter Selasky 
3483f743d78SHans Petter Selasky 	/* restore thread priority */
3493f743d78SHans Petter Selasky 	sched_prio(td, old_prio);
350f3de9af6SHans Petter Selasky 	thread_unlock(td);
351f3de9af6SHans Petter Selasky 
352f3de9af6SHans Petter Selasky 	PICKUP_GIANT();
3531a01b4e5SHans Petter Selasky }
3541a01b4e5SHans Petter Selasky 
3551a01b4e5SHans Petter Selasky void
356eae5868cSHans Petter Selasky linux_rcu_barrier(unsigned type)
3571a01b4e5SHans Petter Selasky {
358f3de9af6SHans Petter Selasky 	struct linux_epoch_head *head;
3591a01b4e5SHans Petter Selasky 
360eae5868cSHans Petter Selasky 	MPASS(type < RCU_TYPE_MAX);
3611f827dabSHans Petter Selasky 
362eae5868cSHans Petter Selasky 	linux_synchronize_rcu(type);
363eae5868cSHans Petter Selasky 
364eae5868cSHans Petter Selasky 	head = &linux_epoch_head[type];
3651f827dabSHans Petter Selasky 
3661f827dabSHans Petter Selasky 	/* wait for callbacks to complete */
367f3de9af6SHans Petter Selasky 	taskqueue_drain(taskqueue_fast, &head->task);
3681a01b4e5SHans Petter Selasky }
3691a01b4e5SHans Petter Selasky 
3701a01b4e5SHans Petter Selasky void
371eae5868cSHans Petter Selasky linux_call_rcu(unsigned type, struct rcu_head *context, rcu_callback_t func)
3721a01b4e5SHans Petter Selasky {
373eae5868cSHans Petter Selasky 	struct callback_head *rcu;
374eae5868cSHans Petter Selasky 	struct linux_epoch_head *head;
375eae5868cSHans Petter Selasky 
376eae5868cSHans Petter Selasky 	MPASS(type < RCU_TYPE_MAX);
377eae5868cSHans Petter Selasky 
378eae5868cSHans Petter Selasky 	rcu = (struct callback_head *)context;
379eae5868cSHans Petter Selasky 	head = &linux_epoch_head[type];
3801a01b4e5SHans Petter Selasky 
381f3de9af6SHans Petter Selasky 	mtx_lock(&head->lock);
3821f827dabSHans Petter Selasky 	rcu->func = func;
383f3de9af6SHans Petter Selasky 	STAILQ_INSERT_TAIL(&head->cb_head, rcu, entry);
384f3de9af6SHans Petter Selasky 	taskqueue_enqueue(taskqueue_fast, &head->task);
385f3de9af6SHans Petter Selasky 	mtx_unlock(&head->lock);
3861a01b4e5SHans Petter Selasky }
3871a01b4e5SHans Petter Selasky 
3881a01b4e5SHans Petter Selasky int
3891a01b4e5SHans Petter Selasky init_srcu_struct(struct srcu_struct *srcu)
3901a01b4e5SHans Petter Selasky {
3911a01b4e5SHans Petter Selasky 	return (0);
3921a01b4e5SHans Petter Selasky }
3931a01b4e5SHans Petter Selasky 
3941a01b4e5SHans Petter Selasky void
3951a01b4e5SHans Petter Selasky cleanup_srcu_struct(struct srcu_struct *srcu)
3961a01b4e5SHans Petter Selasky {
3971a01b4e5SHans Petter Selasky }
3981a01b4e5SHans Petter Selasky 
3991a01b4e5SHans Petter Selasky int
4001a01b4e5SHans Petter Selasky srcu_read_lock(struct srcu_struct *srcu)
4011a01b4e5SHans Petter Selasky {
402eae5868cSHans Petter Selasky 	linux_rcu_read_lock(RCU_TYPE_SLEEPABLE);
4031a01b4e5SHans Petter Selasky 	return (0);
4041a01b4e5SHans Petter Selasky }
4051a01b4e5SHans Petter Selasky 
4061a01b4e5SHans Petter Selasky void
4071a01b4e5SHans Petter Selasky srcu_read_unlock(struct srcu_struct *srcu, int key __unused)
4081a01b4e5SHans Petter Selasky {
409eae5868cSHans Petter Selasky 	linux_rcu_read_unlock(RCU_TYPE_SLEEPABLE);
4101a01b4e5SHans Petter Selasky }
4111a01b4e5SHans Petter Selasky 
4121a01b4e5SHans Petter Selasky void
4131a01b4e5SHans Petter Selasky synchronize_srcu(struct srcu_struct *srcu)
4141a01b4e5SHans Petter Selasky {
415eae5868cSHans Petter Selasky 	linux_synchronize_rcu(RCU_TYPE_SLEEPABLE);
4161f827dabSHans Petter Selasky }
4171f827dabSHans Petter Selasky 
4181f827dabSHans Petter Selasky void
4191f827dabSHans Petter Selasky srcu_barrier(struct srcu_struct *srcu)
4201f827dabSHans Petter Selasky {
421eae5868cSHans Petter Selasky 	linux_rcu_barrier(RCU_TYPE_SLEEPABLE);
4221a01b4e5SHans Petter Selasky }
423