1/* $NetBSD: kern_kthread.c,v 1.41 2015/04/21 11:10:29 pooka Exp $ */
2
3/*-
4 * Copyright (c) 1998, 1999, 2007, 2009 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
9 * NASA Ames Research Center, and by Andrew Doran.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33#include <sys/cdefs.h>
34__KERNEL_RCSID(0, "$NetBSD: kern_kthread.c,v 1.41 2015/04/21 11:10:29 pooka Exp $");
35
36#include <sys/param.h>
37#include <sys/systm.h>
38#include <sys/kernel.h>
39#include <sys/kthread.h>
40#include <sys/mutex.h>
41#include <sys/sched.h>
42#include <sys/kmem.h>
43
44#include <uvm/uvm_extern.h>
45
46static lwp_t * kthread_jtarget;
47static kmutex_t kthread_lock;
48static kcondvar_t kthread_cv;
49
50void
51kthread_sysinit(void)
52{
53
54 mutex_init(&kthread_lock, MUTEX_DEFAULT, IPL_NONE);
55 cv_init(&kthread_cv, "kthrwait");
56 kthread_jtarget = NULL;
57}
58
59/*
60 * kthread_create: create a kernel thread, that is, system-only LWP.
61 */
62int
63kthread_create(pri_t pri, int flag, struct cpu_info *ci,
64 void (*func)(void *), void *arg, lwp_t **lp, const char *fmt, ...)
65{
66 lwp_t *l;
67 vaddr_t uaddr;
68 int error, lc;
69 va_list ap;
70
71 KASSERT((flag & KTHREAD_INTR) == 0 || (flag & KTHREAD_MPSAFE) != 0);
72
73 uaddr = uvm_uarea_system_alloc(
74 (flag & (KTHREAD_INTR|KTHREAD_IDLE)) == KTHREAD_IDLE ? ci : NULL);
75 if (uaddr == 0) {
76 return ENOMEM;
77 }
78 if ((flag & KTHREAD_TS) != 0) {
79 lc = SCHED_OTHER;
80 } else {
81 lc = SCHED_RR;
82 }
83
84 error = lwp_create(&lwp0, &proc0, uaddr, LWP_DETACHED, NULL,
85 0, func, arg, &l, lc);
86 if (error) {
87 uvm_uarea_system_free(uaddr);
88 return error;
89 }
90 if (fmt != NULL) {
91 l->l_name = kmem_alloc(MAXCOMLEN, KM_SLEEP);
92 va_start(ap, fmt);
93 vsnprintf(l->l_name, MAXCOMLEN, fmt, ap);
94 va_end(ap);
95 }
96
97 /*
98 * Set parameters.
99 */
100 if (pri == PRI_NONE) {
101 if ((flag & KTHREAD_TS) != 0) {
102 /* Maximum user priority level. */
103 pri = MAXPRI_USER;
104 } else {
105 /* Minimum kernel priority level. */
106 pri = PRI_KTHREAD;
107 }
108 }
109 mutex_enter(proc0.p_lock);
110 lwp_lock(l);
111 l->l_priority = pri;
112 if (ci != NULL) {
113 if (ci != l->l_cpu) {
114 lwp_unlock_to(l, ci->ci_schedstate.spc_mutex);
115 lwp_lock(l);
116 }
117 l->l_pflag |= LP_BOUND;
118 l->l_cpu = ci;
119 }
120
121 if ((flag & KTHREAD_MUSTJOIN) != 0) {
122 KASSERT(lp != NULL);
123 l->l_pflag |= LP_MUSTJOIN;
124 }
125 if ((flag & KTHREAD_INTR) != 0) {
126 l->l_pflag |= LP_INTR;
127 }
128 if ((flag & KTHREAD_MPSAFE) == 0) {
129 l->l_pflag &= ~LP_MPSAFE;
130 }
131
132 /*
133 * Set the new LWP running, unless the caller has requested
134 * otherwise.
135 */
136 if ((flag & KTHREAD_IDLE) == 0) {
137 l->l_stat = LSRUN;
138 sched_enqueue(l, false);
139 lwp_unlock(l);
140 } else {
141 if (ci != NULL)
142 lwp_unlock_to(l, ci->ci_schedstate.spc_lwplock);
143 else
144 lwp_unlock(l);
145 }
146 mutex_exit(proc0.p_lock);
147
148 /* All done! */
149 if (lp != NULL) {
150 *lp = l;
151 }
152 return 0;
153}
154
155/*
156 * Cause a kernel thread to exit. Assumes the exiting thread is the
157 * current context.
158 */
159void
160kthread_exit(int ecode)
161{
162 const char *name;
163 lwp_t *l = curlwp;
164
165 /* We can't do much with the exit code, so just report it. */
166 if (ecode != 0) {
167 if ((name = l->l_name) == NULL)
168 name = "unnamed";
169 printf("WARNING: kthread `%s' (%d) exits with status %d\n",
170 name, l->l_lid, ecode);
171 }
172
173 /* Barrier for joining. */
174 if (l->l_pflag & LP_MUSTJOIN) {
175 mutex_enter(&kthread_lock);
176 while (kthread_jtarget != l) {
177 cv_wait(&kthread_cv, &kthread_lock);
178 }
179 kthread_jtarget = NULL;
180 cv_broadcast(&kthread_cv);
181 mutex_exit(&kthread_lock);
182 }
183
184 /* And exit.. */
185 lwp_exit(l);
186 panic("kthread_exit");
187}
188
189/*
190 * Wait for a kthread to exit, as pthread_join().
191 */
192int
193kthread_join(lwp_t *l)
194{
195
196 KASSERT((l->l_flag & LW_SYSTEM) != 0);
197
198 /*
199 * - Wait if some other thread has occupied the target.
200 * - Specify our kthread as a target and notify it.
201 * - Wait for the target kthread to notify us.
202 */
203 mutex_enter(&kthread_lock);
204 while (kthread_jtarget) {
205 cv_wait(&kthread_cv, &kthread_lock);
206 }
207 kthread_jtarget = l;
208 cv_broadcast(&kthread_cv);
209 while (kthread_jtarget == l) {
210 cv_wait(&kthread_cv, &kthread_lock);
211 }
212 mutex_exit(&kthread_lock);
213
214 return 0;
215}
216