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 | |
46 | static lwp_t * kthread_jtarget; |
47 | static kmutex_t kthread_lock; |
48 | static kcondvar_t kthread_cv; |
49 | |
50 | void |
51 | kthread_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 | */ |
62 | int |
63 | kthread_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 | */ |
159 | void |
160 | kthread_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 | */ |
192 | int |
193 | kthread_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 | |