1 /*-
2 * Copyright (c) 1999 Peter Wemm <peter@FreeBSD.org>
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, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD: releng/7.3/sys/kern/kern_kthread.c 170307 2007-06-05 00:00:57Z jeff $");
29
30 #include <sys/param.h>
31 #include <sys/systm.h>
32 #include <sys/kthread.h>
33 #include <sys/lock.h>
34 #include <sys/mutex.h>
35 #include <sys/proc.h>
36 #include <sys/resourcevar.h>
37 #include <sys/signalvar.h>
38 #include <sys/sx.h>
39 #include <sys/unistd.h>
40 #include <sys/wait.h>
41 #include <sys/sched.h>
42
43 #include <machine/stdarg.h>
44
45 /*
46 * Start a kernel process. This is called after a fork() call in
47 * mi_startup() in the file kern/init_main.c.
48 *
49 * This function is used to start "internal" daemons and intended
50 * to be called from SYSINIT().
51 */
52 void
53 kproc_start(udata)
54 const void *udata;
55 {
56 const struct kproc_desc *kp = udata;
57 int error;
58
59 error = kthread_create((void (*)(void *))kp->func, NULL,
60 kp->global_procpp, 0, 0, "%s", kp->arg0);
61 if (error)
62 panic("kproc_start: %s: error %d", kp->arg0, error);
63 }
64
65 /*
66 * Create a kernel process/thread/whatever. It shares its address space
67 * with proc0 - ie: kernel only.
68 *
69 * func is the function to start.
70 * arg is the parameter to pass to function on first startup.
71 * newpp is the return value pointing to the thread's struct proc.
72 * flags are flags to fork1 (in unistd.h)
73 * fmt and following will be *printf'd into (*newpp)->p_comm (for ps, etc.).
74 */
75 int
76 kthread_create(void (*func)(void *), void *arg,
77 struct proc **newpp, int flags, int pages, const char *fmt, ...)
78 {
79 int error;
80 va_list ap;
81 struct thread *td;
82 struct proc *p2;
83
84 if (!proc0.p_stats)
85 panic("kthread_create called too soon");
86
87 error = fork1(&thread0, RFMEM | RFFDG | RFPROC | RFSTOPPED | flags,
88 pages, &p2);
89 if (error)
90 return error;
91
92 /* save a global descriptor, if desired */
93 if (newpp != NULL)
94 *newpp = p2;
95
96 /* this is a non-swapped system process */
97 PROC_LOCK(p2);
98 p2->p_flag |= P_SYSTEM | P_KTHREAD;
99 mtx_lock(&p2->p_sigacts->ps_mtx);
100 p2->p_sigacts->ps_flag |= PS_NOCLDWAIT;
101 mtx_unlock(&p2->p_sigacts->ps_mtx);
102 PROC_UNLOCK(p2);
103
104 /* set up arg0 for 'ps', et al */
105 va_start(ap, fmt);
106 vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap);
107 va_end(ap);
108
109 /* call the processes' main()... */
110 td = FIRST_THREAD_IN_PROC(p2);
111 cpu_set_fork_handler(td, func, arg);
112 TD_SET_CAN_RUN(td);
113
114 /* Delay putting it on the run queue until now. */
115 if (!(flags & RFSTOPPED)) {
116 thread_lock(td);
117 sched_add(td, SRQ_BORING);
118 thread_unlock(td);
119 }
120
121 return 0;
122 }
123
124 void
125 kthread_exit(int ecode)
126 {
127 struct thread *td;
128 struct proc *p;
129
130 td = curthread;
131 p = td->td_proc;
132
133 /*
134 * Reparent curthread from proc0 to init so that the zombie
135 * is harvested.
136 */
137 sx_xlock(&proctree_lock);
138 PROC_LOCK(p);
139 proc_reparent(p, initproc);
140 PROC_UNLOCK(p);
141 sx_xunlock(&proctree_lock);
142
143 /*
144 * Wakeup anyone waiting for us to exit.
145 */
146 wakeup(p);
147
148 /* Buh-bye! */
149 exit1(td, W_EXITCODE(ecode, 0));
150 }
151
152 /*
153 * Advise a kernel process to suspend (or resume) in its main loop.
154 * Participation is voluntary.
155 */
156 int
157 kthread_suspend(struct proc *p, int timo)
158 {
159 /*
160 * Make sure this is indeed a system process and we can safely
161 * use the p_siglist field.
162 */
163 PROC_LOCK(p);
164 if ((p->p_flag & P_KTHREAD) == 0) {
165 PROC_UNLOCK(p);
166 return (EINVAL);
167 }
168 SIGADDSET(p->p_siglist, SIGSTOP);
169 wakeup(p);
170 return msleep(&p->p_siglist, &p->p_mtx, PPAUSE | PDROP, "suspkt", timo);
171 }
172
173 int
174 kthread_resume(struct proc *p)
175 {
176 /*
177 * Make sure this is indeed a system process and we can safely
178 * use the p_siglist field.
179 */
180 PROC_LOCK(p);
181 if ((p->p_flag & P_KTHREAD) == 0) {
182 PROC_UNLOCK(p);
183 return (EINVAL);
184 }
185 SIGDELSET(p->p_siglist, SIGSTOP);
186 PROC_UNLOCK(p);
187 wakeup(&p->p_siglist);
188 return (0);
189 }
190
191 void
192 kthread_suspend_check(struct proc *p)
193 {
194 PROC_LOCK(p);
195 while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
196 wakeup(&p->p_siglist);
197 msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "ktsusp", 0);
198 }
199 PROC_UNLOCK(p);
200 }
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