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/9.0/sys/kern/kern_kthread.c 224987 2011-08-18 22:51:30Z jonathan $");
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/rwlock.h>
38 #include <sys/signalvar.h>
39 #include <sys/sx.h>
40 #include <sys/unistd.h>
41 #include <sys/wait.h>
42 #include <sys/sched.h>
43 #include <vm/vm.h>
44 #include <vm/vm_extern.h>
45
46 #include <machine/stdarg.h>
47
48 /*
49 * Start a kernel process. This is called after a fork() call in
50 * mi_startup() in the file kern/init_main.c.
51 *
52 * This function is used to start "internal" daemons and intended
53 * to be called from SYSINIT().
54 */
55 void
56 kproc_start(udata)
57 const void *udata;
58 {
59 const struct kproc_desc *kp = udata;
60 int error;
61
62 error = kproc_create((void (*)(void *))kp->func, NULL,
63 kp->global_procpp, 0, 0, "%s", kp->arg0);
64 if (error)
65 panic("kproc_start: %s: error %d", kp->arg0, error);
66 }
67
68 /*
69 * Create a kernel process/thread/whatever. It shares its address space
70 * with proc0 - ie: kernel only.
71 *
72 * func is the function to start.
73 * arg is the parameter to pass to function on first startup.
74 * newpp is the return value pointing to the thread's struct proc.
75 * flags are flags to fork1 (in unistd.h)
76 * fmt and following will be *printf'd into (*newpp)->p_comm (for ps, etc.).
77 */
78 int
79 kproc_create(void (*func)(void *), void *arg,
80 struct proc **newpp, int flags, int pages, const char *fmt, ...)
81 {
82 int error;
83 va_list ap;
84 struct thread *td;
85 struct proc *p2;
86
87 if (!proc0.p_stats)
88 panic("kproc_create called too soon");
89
90 error = fork1(&thread0, RFMEM | RFFDG | RFPROC | RFSTOPPED | flags,
91 pages, &p2, NULL, 0);
92 if (error)
93 return error;
94
95 /* save a global descriptor, if desired */
96 if (newpp != NULL)
97 *newpp = p2;
98
99 /* this is a non-swapped system process */
100 PROC_LOCK(p2);
101 td = FIRST_THREAD_IN_PROC(p2);
102 p2->p_flag |= P_SYSTEM | P_KTHREAD;
103 td->td_pflags |= TDP_KTHREAD;
104 mtx_lock(&p2->p_sigacts->ps_mtx);
105 p2->p_sigacts->ps_flag |= PS_NOCLDWAIT;
106 mtx_unlock(&p2->p_sigacts->ps_mtx);
107 PROC_UNLOCK(p2);
108
109 /* set up arg0 for 'ps', et al */
110 va_start(ap, fmt);
111 vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap);
112 va_end(ap);
113 /* set up arg0 for 'ps', et al */
114 va_start(ap, fmt);
115 vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
116 va_end(ap);
117
118 /* call the processes' main()... */
119 cpu_set_fork_handler(td, func, arg);
120 thread_lock(td);
121 TD_SET_CAN_RUN(td);
122 sched_prio(td, PVM);
123 sched_user_prio(td, PUSER);
124
125 /* Delay putting it on the run queue until now. */
126 if (!(flags & RFSTOPPED))
127 sched_add(td, SRQ_BORING);
128 thread_unlock(td);
129
130 return 0;
131 }
132
133 void
134 kproc_exit(int ecode)
135 {
136 struct thread *td;
137 struct proc *p;
138
139 td = curthread;
140 p = td->td_proc;
141
142 /*
143 * Reparent curthread from proc0 to init so that the zombie
144 * is harvested.
145 */
146 sx_xlock(&proctree_lock);
147 PROC_LOCK(p);
148 proc_reparent(p, initproc);
149 PROC_UNLOCK(p);
150 sx_xunlock(&proctree_lock);
151
152 /*
153 * Wakeup anyone waiting for us to exit.
154 */
155 wakeup(p);
156
157 /* Buh-bye! */
158 exit1(td, W_EXITCODE(ecode, 0));
159 }
160
161 /*
162 * Advise a kernel process to suspend (or resume) in its main loop.
163 * Participation is voluntary.
164 */
165 int
166 kproc_suspend(struct proc *p, int timo)
167 {
168 /*
169 * Make sure this is indeed a system process and we can safely
170 * use the p_siglist field.
171 */
172 PROC_LOCK(p);
173 if ((p->p_flag & P_KTHREAD) == 0) {
174 PROC_UNLOCK(p);
175 return (EINVAL);
176 }
177 SIGADDSET(p->p_siglist, SIGSTOP);
178 wakeup(p);
179 return msleep(&p->p_siglist, &p->p_mtx, PPAUSE | PDROP, "suspkp", timo);
180 }
181
182 int
183 kproc_resume(struct proc *p)
184 {
185 /*
186 * Make sure this is indeed a system process and we can safely
187 * use the p_siglist field.
188 */
189 PROC_LOCK(p);
190 if ((p->p_flag & P_KTHREAD) == 0) {
191 PROC_UNLOCK(p);
192 return (EINVAL);
193 }
194 SIGDELSET(p->p_siglist, SIGSTOP);
195 PROC_UNLOCK(p);
196 wakeup(&p->p_siglist);
197 return (0);
198 }
199
200 void
201 kproc_suspend_check(struct proc *p)
202 {
203 PROC_LOCK(p);
204 while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
205 wakeup(&p->p_siglist);
206 msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "kpsusp", 0);
207 }
208 PROC_UNLOCK(p);
209 }
210
211
212 /*
213 * Start a kernel thread.
214 *
215 * This function is used to start "internal" daemons and intended
216 * to be called from SYSINIT().
217 */
218
219 void
220 kthread_start(udata)
221 const void *udata;
222 {
223 const struct kthread_desc *kp = udata;
224 int error;
225
226 error = kthread_add((void (*)(void *))kp->func, NULL,
227 NULL, kp->global_threadpp, 0, 0, "%s", kp->arg0);
228 if (error)
229 panic("kthread_start: %s: error %d", kp->arg0, error);
230 }
231
232 /*
233 * Create a kernel thread. It shares its address space
234 * with proc0 - ie: kernel only.
235 *
236 * func is the function to start.
237 * arg is the parameter to pass to function on first startup.
238 * newtdp is the return value pointing to the thread's struct thread.
239 * ** XXX fix this --> flags are flags to fork1 (in unistd.h)
240 * fmt and following will be *printf'd into (*newtd)->td_name (for ps, etc.).
241 */
242 int
243 kthread_add(void (*func)(void *), void *arg, struct proc *p,
244 struct thread **newtdp, int flags, int pages, const char *fmt, ...)
245 {
246 va_list ap;
247 struct thread *newtd, *oldtd;
248
249 if (!proc0.p_stats)
250 panic("kthread_add called too soon");
251
252 /* If no process supplied, put it on proc0 */
253 if (p == NULL) {
254 p = &proc0;
255 oldtd = &thread0;
256 } else {
257 oldtd = FIRST_THREAD_IN_PROC(p);
258 }
259
260 /* Initialize our new td */
261 newtd = thread_alloc(pages);
262 if (newtd == NULL)
263 return (ENOMEM);
264
265 bzero(&newtd->td_startzero,
266 __rangeof(struct thread, td_startzero, td_endzero));
267 /* XXX check if we should zero. */
268 bcopy(&oldtd->td_startcopy, &newtd->td_startcopy,
269 __rangeof(struct thread, td_startcopy, td_endcopy));
270
271 /* set up arg0 for 'ps', et al */
272 va_start(ap, fmt);
273 vsnprintf(newtd->td_name, sizeof(newtd->td_name), fmt, ap);
274 va_end(ap);
275
276 newtd->td_proc = p; /* needed for cpu_set_upcall */
277
278 /* XXX optimise this probably? */
279 /* On x86 (and probably the others too) it is way too full of junk */
280 /* Needs a better name */
281 cpu_set_upcall(newtd, oldtd);
282 /* put the designated function(arg) as the resume context */
283 cpu_set_fork_handler(newtd, func, arg);
284
285 newtd->td_pflags |= TDP_KTHREAD;
286 newtd->td_ucred = crhold(p->p_ucred);
287
288 /* this code almost the same as create_thread() in kern_thr.c */
289 PROC_LOCK(p);
290 p->p_flag |= P_HADTHREADS;
291 newtd->td_sigmask = oldtd->td_sigmask; /* XXX dubious */
292 thread_link(newtd, p);
293 thread_lock(oldtd);
294 /* let the scheduler know about these things. */
295 sched_fork_thread(oldtd, newtd);
296 TD_SET_CAN_RUN(newtd);
297 thread_unlock(oldtd);
298 PROC_UNLOCK(p);
299
300 tidhash_add(newtd);
301
302 /* Delay putting it on the run queue until now. */
303 if (!(flags & RFSTOPPED)) {
304 thread_lock(newtd);
305 sched_add(newtd, SRQ_BORING);
306 thread_unlock(newtd);
307 }
308 if (newtdp)
309 *newtdp = newtd;
310 return 0;
311 }
312
313 void
314 kthread_exit(void)
315 {
316 struct proc *p;
317
318 p = curthread->td_proc;
319
320 /* A module may be waiting for us to exit. */
321 wakeup(curthread);
322
323 /*
324 * The last exiting thread in a kernel process must tear down
325 * the whole process.
326 */
327 rw_wlock(&tidhash_lock);
328 PROC_LOCK(p);
329 if (p->p_numthreads == 1) {
330 PROC_UNLOCK(p);
331 rw_wunlock(&tidhash_lock);
332 kproc_exit(0);
333 }
334 LIST_REMOVE(curthread, td_hash);
335 rw_wunlock(&tidhash_lock);
336 PROC_SLOCK(p);
337 thread_exit();
338 }
339
340 /*
341 * Advise a kernel process to suspend (or resume) in its main loop.
342 * Participation is voluntary.
343 */
344 int
345 kthread_suspend(struct thread *td, int timo)
346 {
347 struct proc *p;
348
349 p = td->td_proc;
350
351 /*
352 * td_pflags should not be read by any thread other than
353 * curthread, but as long as this flag is invariant during the
354 * thread's lifetime, it is OK to check its state.
355 */
356 if ((td->td_pflags & TDP_KTHREAD) == 0)
357 return (EINVAL);
358
359 /*
360 * The caller of the primitive should have already checked that the
361 * thread is up and running, thus not being blocked by other
362 * conditions.
363 */
364 PROC_LOCK(p);
365 thread_lock(td);
366 td->td_flags |= TDF_KTH_SUSP;
367 thread_unlock(td);
368 return (msleep(&td->td_flags, &p->p_mtx, PPAUSE | PDROP, "suspkt",
369 timo));
370 }
371
372 /*
373 * Resume a thread previously put asleep with kthread_suspend().
374 */
375 int
376 kthread_resume(struct thread *td)
377 {
378 struct proc *p;
379
380 p = td->td_proc;
381
382 /*
383 * td_pflags should not be read by any thread other than
384 * curthread, but as long as this flag is invariant during the
385 * thread's lifetime, it is OK to check its state.
386 */
387 if ((td->td_pflags & TDP_KTHREAD) == 0)
388 return (EINVAL);
389
390 PROC_LOCK(p);
391 thread_lock(td);
392 td->td_flags &= ~TDF_KTH_SUSP;
393 thread_unlock(td);
394 wakeup(&td->td_flags);
395 PROC_UNLOCK(p);
396 return (0);
397 }
398
399 /*
400 * Used by the thread to poll as to whether it should yield/sleep
401 * and notify the caller that is has happened.
402 */
403 void
404 kthread_suspend_check()
405 {
406 struct proc *p;
407 struct thread *td;
408
409 td = curthread;
410 p = td->td_proc;
411
412 if ((td->td_pflags & TDP_KTHREAD) == 0)
413 panic("%s: curthread is not a valid kthread", __func__);
414
415 /*
416 * As long as the double-lock protection is used when accessing the
417 * TDF_KTH_SUSP flag, synchronizing the read operation via proc mutex
418 * is fine.
419 */
420 PROC_LOCK(p);
421 while (td->td_flags & TDF_KTH_SUSP) {
422 wakeup(&td->td_flags);
423 msleep(&td->td_flags, &p->p_mtx, PPAUSE, "ktsusp", 0);
424 }
425 PROC_UNLOCK(p);
426 }
427
428 int
429 kproc_kthread_add(void (*func)(void *), void *arg,
430 struct proc **procptr, struct thread **tdptr,
431 int flags, int pages, const char *procname, const char *fmt, ...)
432 {
433 int error;
434 va_list ap;
435 char buf[100];
436 struct thread *td;
437
438 if (*procptr == 0) {
439 error = kproc_create(func, arg,
440 procptr, flags, pages, "%s", procname);
441 if (error)
442 return (error);
443 td = FIRST_THREAD_IN_PROC(*procptr);
444 if (tdptr)
445 *tdptr = td;
446 va_start(ap, fmt);
447 vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
448 va_end(ap);
449 return (0);
450 }
451 va_start(ap, fmt);
452 vsnprintf(buf, sizeof(buf), fmt, ap);
453 va_end(ap);
454 error = kthread_add(func, arg, *procptr,
455 tdptr, flags, pages, "%s", buf);
456 return (error);
457 }
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