xref: /freebsd/sys/kern/kern_kthread.c (revision 56e53cb8ef000c3ef72337a4095987a932cdedef)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 1999 Peter Wemm <peter@FreeBSD.org>
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31 
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/cpuset.h>
35 #include <sys/kthread.h>
36 #include <sys/lock.h>
37 #include <sys/mutex.h>
38 #include <sys/proc.h>
39 #include <sys/resourcevar.h>
40 #include <sys/rwlock.h>
41 #include <sys/signalvar.h>
42 #include <sys/sx.h>
43 #include <sys/umtx.h>
44 #include <sys/unistd.h>
45 #include <sys/wait.h>
46 #include <sys/sched.h>
47 #include <sys/tslog.h>
48 #include <vm/vm.h>
49 #include <vm/vm_extern.h>
50 
51 #include <machine/stdarg.h>
52 
53 /*
54  * Start a kernel process.  This is called after a fork() call in
55  * mi_startup() in the file kern/init_main.c.
56  *
57  * This function is used to start "internal" daemons and intended
58  * to be called from SYSINIT().
59  */
60 void
61 kproc_start(const void *udata)
62 {
63 	const struct kproc_desc	*kp = udata;
64 	int error;
65 
66 	error = kproc_create((void (*)(void *))kp->func, NULL,
67 		    kp->global_procpp, 0, 0, "%s", kp->arg0);
68 	if (error)
69 		panic("kproc_start: %s: error %d", kp->arg0, error);
70 }
71 
72 /*
73  * Create a kernel process/thread/whatever.  It shares its address space
74  * with proc0 - ie: kernel only.
75  *
76  * func is the function to start.
77  * arg is the parameter to pass to function on first startup.
78  * newpp is the return value pointing to the thread's struct proc.
79  * flags are flags to fork1 (in unistd.h)
80  * fmt and following will be *printf'd into (*newpp)->p_comm (for ps, etc.).
81  */
82 int
83 kproc_create(void (*func)(void *), void *arg,
84     struct proc **newpp, int flags, int pages, const char *fmt, ...)
85 {
86 	struct fork_req fr;
87 	int error;
88 	va_list ap;
89 	struct thread *td;
90 	struct proc *p2;
91 
92 	if (!proc0.p_stats)
93 		panic("kproc_create called too soon");
94 
95 	bzero(&fr, sizeof(fr));
96 	fr.fr_flags = RFMEM | RFFDG | RFPROC | RFSTOPPED | flags;
97 	fr.fr_pages = pages;
98 	fr.fr_procp = &p2;
99 	error = fork1(&thread0, &fr);
100 	if (error)
101 		return error;
102 
103 	/* save a global descriptor, if desired */
104 	if (newpp != NULL)
105 		*newpp = p2;
106 
107 	/* this is a non-swapped system process */
108 	PROC_LOCK(p2);
109 	td = FIRST_THREAD_IN_PROC(p2);
110 	p2->p_flag |= P_SYSTEM | P_KPROC;
111 	td->td_pflags |= TDP_KTHREAD;
112 	mtx_lock(&p2->p_sigacts->ps_mtx);
113 	p2->p_sigacts->ps_flag |= PS_NOCLDWAIT;
114 	mtx_unlock(&p2->p_sigacts->ps_mtx);
115 	PROC_UNLOCK(p2);
116 
117 	/* set up arg0 for 'ps', et al */
118 	va_start(ap, fmt);
119 	vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap);
120 	va_end(ap);
121 	/* set up arg0 for 'ps', et al */
122 	va_start(ap, fmt);
123 	vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
124 	va_end(ap);
125 #ifdef KTR
126 	sched_clear_tdname(td);
127 #endif
128 	TSTHREAD(td, td->td_name);
129 
130 	/* call the processes' main()... */
131 	cpu_fork_kthread_handler(td, func, arg);
132 
133 	/* Avoid inheriting affinity from a random parent. */
134 	cpuset_setthread(td->td_tid, cpuset_root);
135 	thread_lock(td);
136 	TD_SET_CAN_RUN(td);
137 	sched_prio(td, PVM);
138 	sched_user_prio(td, PUSER);
139 
140 	/* Delay putting it on the run queue until now. */
141 	if (!(flags & RFSTOPPED))
142 		sched_add(td, SRQ_BORING);
143 	thread_unlock(td);
144 
145 	return 0;
146 }
147 
148 void
149 kproc_exit(int ecode)
150 {
151 	struct thread *td;
152 	struct proc *p;
153 
154 	td = curthread;
155 	p = td->td_proc;
156 
157 	/*
158 	 * Reparent curthread from proc0 to init so that the zombie
159 	 * is harvested.
160 	 */
161 	sx_xlock(&proctree_lock);
162 	PROC_LOCK(p);
163 	proc_reparent(p, initproc);
164 	PROC_UNLOCK(p);
165 	sx_xunlock(&proctree_lock);
166 
167 	/*
168 	 * Wakeup anyone waiting for us to exit.
169 	 */
170 	wakeup(p);
171 
172 	/* Buh-bye! */
173 	exit1(td, ecode, 0);
174 }
175 
176 /*
177  * Advise a kernel process to suspend (or resume) in its main loop.
178  * Participation is voluntary.
179  */
180 int
181 kproc_suspend(struct proc *p, int timo)
182 {
183 	/*
184 	 * Make sure this is indeed a system process and we can safely
185 	 * use the p_siglist field.
186 	 */
187 	PROC_LOCK(p);
188 	if ((p->p_flag & P_KPROC) == 0) {
189 		PROC_UNLOCK(p);
190 		return (EINVAL);
191 	}
192 	SIGADDSET(p->p_siglist, SIGSTOP);
193 	wakeup(p);
194 	return msleep(&p->p_siglist, &p->p_mtx, PPAUSE | PDROP, "suspkp", timo);
195 }
196 
197 int
198 kproc_resume(struct proc *p)
199 {
200 	/*
201 	 * Make sure this is indeed a system process and we can safely
202 	 * use the p_siglist field.
203 	 */
204 	PROC_LOCK(p);
205 	if ((p->p_flag & P_KPROC) == 0) {
206 		PROC_UNLOCK(p);
207 		return (EINVAL);
208 	}
209 	SIGDELSET(p->p_siglist, SIGSTOP);
210 	PROC_UNLOCK(p);
211 	wakeup(&p->p_siglist);
212 	return (0);
213 }
214 
215 void
216 kproc_suspend_check(struct proc *p)
217 {
218 	PROC_LOCK(p);
219 	while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
220 		wakeup(&p->p_siglist);
221 		msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "kpsusp", 0);
222 	}
223 	PROC_UNLOCK(p);
224 }
225 
226 
227 /*
228  * Start a kernel thread.
229  *
230  * This function is used to start "internal" daemons and intended
231  * to be called from SYSINIT().
232  */
233 
234 void
235 kthread_start(const void *udata)
236 {
237 	const struct kthread_desc	*kp = udata;
238 	int error;
239 
240 	error = kthread_add((void (*)(void *))kp->func, NULL,
241 		    NULL, kp->global_threadpp, 0, 0, "%s", kp->arg0);
242 	if (error)
243 		panic("kthread_start: %s: error %d", kp->arg0, error);
244 }
245 
246 /*
247  * Create a kernel thread.  It shares its address space
248  * with proc0 - ie: kernel only.
249  *
250  * func is the function to start.
251  * arg is the parameter to pass to function on first startup.
252  * newtdp is the return value pointing to the thread's struct thread.
253  *  ** XXX fix this --> flags are flags to fork1 (in unistd.h)
254  * fmt and following will be *printf'd into (*newtd)->td_name (for ps, etc.).
255  */
256 int
257 kthread_add(void (*func)(void *), void *arg, struct proc *p,
258     struct thread **newtdp, int flags, int pages, const char *fmt, ...)
259 {
260 	va_list ap;
261 	struct thread *newtd, *oldtd;
262 
263 	if (!proc0.p_stats)
264 		panic("kthread_add called too soon");
265 
266 	/* If no process supplied, put it on proc0 */
267 	if (p == NULL)
268 		p = &proc0;
269 
270 	/* Initialize our new td  */
271 	newtd = thread_alloc(pages);
272 	if (newtd == NULL)
273 		return (ENOMEM);
274 
275 	PROC_LOCK(p);
276 	oldtd = FIRST_THREAD_IN_PROC(p);
277 
278 	bzero(&newtd->td_startzero,
279 	    __rangeof(struct thread, td_startzero, td_endzero));
280 	bcopy(&oldtd->td_startcopy, &newtd->td_startcopy,
281 	    __rangeof(struct thread, td_startcopy, td_endcopy));
282 
283 	/* set up arg0 for 'ps', et al */
284 	va_start(ap, fmt);
285 	vsnprintf(newtd->td_name, sizeof(newtd->td_name), fmt, ap);
286 	va_end(ap);
287 
288 	TSTHREAD(newtd, newtd->td_name);
289 
290 	newtd->td_proc = p;  /* needed for cpu_copy_thread */
291 	/* might be further optimized for kthread */
292 	cpu_copy_thread(newtd, oldtd);
293 	/* put the designated function(arg) as the resume context */
294 	cpu_fork_kthread_handler(newtd, func, arg);
295 
296 	newtd->td_pflags |= TDP_KTHREAD;
297 	thread_cow_get_proc(newtd, p);
298 
299 	/* this code almost the same as create_thread() in kern_thr.c */
300 	p->p_flag |= P_HADTHREADS;
301 	thread_link(newtd, p);
302 	thread_lock(oldtd);
303 	/* let the scheduler know about these things. */
304 	sched_fork_thread(oldtd, newtd);
305 	TD_SET_CAN_RUN(newtd);
306 	thread_unlock(oldtd);
307 	PROC_UNLOCK(p);
308 
309 	tidhash_add(newtd);
310 
311 	/* Avoid inheriting affinity from a random parent. */
312 	cpuset_setthread(newtd->td_tid, cpuset_root);
313 
314 	/* Delay putting it on the run queue until now. */
315 	if (!(flags & RFSTOPPED)) {
316 		thread_lock(newtd);
317 		sched_add(newtd, SRQ_BORING);
318 		thread_unlock(newtd);
319 	}
320 	if (newtdp)
321 		*newtdp = newtd;
322 	return 0;
323 }
324 
325 void
326 kthread_exit(void)
327 {
328 	struct proc *p;
329 	struct thread *td;
330 
331 	td = curthread;
332 	p = td->td_proc;
333 
334 	/* A module may be waiting for us to exit. */
335 	wakeup(td);
336 
337 	/*
338 	 * The last exiting thread in a kernel process must tear down
339 	 * the whole process.
340 	 */
341 	rw_wlock(&tidhash_lock);
342 	PROC_LOCK(p);
343 	if (p->p_numthreads == 1) {
344 		PROC_UNLOCK(p);
345 		rw_wunlock(&tidhash_lock);
346 		kproc_exit(0);
347 	}
348 	LIST_REMOVE(td, td_hash);
349 	rw_wunlock(&tidhash_lock);
350 	umtx_thread_exit(td);
351 	tdsigcleanup(td);
352 	PROC_SLOCK(p);
353 	thread_exit();
354 }
355 
356 /*
357  * Advise a kernel process to suspend (or resume) in its main loop.
358  * Participation is voluntary.
359  */
360 int
361 kthread_suspend(struct thread *td, int timo)
362 {
363 	struct proc *p;
364 
365 	p = td->td_proc;
366 
367 	/*
368 	 * td_pflags should not be read by any thread other than
369 	 * curthread, but as long as this flag is invariant during the
370 	 * thread's lifetime, it is OK to check its state.
371 	 */
372 	if ((td->td_pflags & TDP_KTHREAD) == 0)
373 		return (EINVAL);
374 
375 	/*
376 	 * The caller of the primitive should have already checked that the
377 	 * thread is up and running, thus not being blocked by other
378 	 * conditions.
379 	 */
380 	PROC_LOCK(p);
381 	thread_lock(td);
382 	td->td_flags |= TDF_KTH_SUSP;
383 	thread_unlock(td);
384 	return (msleep(&td->td_flags, &p->p_mtx, PPAUSE | PDROP, "suspkt",
385 	    timo));
386 }
387 
388 /*
389  * Resume a thread previously put asleep with kthread_suspend().
390  */
391 int
392 kthread_resume(struct thread *td)
393 {
394 	struct proc *p;
395 
396 	p = td->td_proc;
397 
398 	/*
399 	 * td_pflags should not be read by any thread other than
400 	 * curthread, but as long as this flag is invariant during the
401 	 * thread's lifetime, it is OK to check its state.
402 	 */
403 	if ((td->td_pflags & TDP_KTHREAD) == 0)
404 		return (EINVAL);
405 
406 	PROC_LOCK(p);
407 	thread_lock(td);
408 	td->td_flags &= ~TDF_KTH_SUSP;
409 	thread_unlock(td);
410 	wakeup(&td->td_flags);
411 	PROC_UNLOCK(p);
412 	return (0);
413 }
414 
415 /*
416  * Used by the thread to poll as to whether it should yield/sleep
417  * and notify the caller that is has happened.
418  */
419 void
420 kthread_suspend_check(void)
421 {
422 	struct proc *p;
423 	struct thread *td;
424 
425 	td = curthread;
426 	p = td->td_proc;
427 
428 	if ((td->td_pflags & TDP_KTHREAD) == 0)
429 		panic("%s: curthread is not a valid kthread", __func__);
430 
431 	/*
432 	 * As long as the double-lock protection is used when accessing the
433 	 * TDF_KTH_SUSP flag, synchronizing the read operation via proc mutex
434 	 * is fine.
435 	 */
436 	PROC_LOCK(p);
437 	while (td->td_flags & TDF_KTH_SUSP) {
438 		wakeup(&td->td_flags);
439 		msleep(&td->td_flags, &p->p_mtx, PPAUSE, "ktsusp", 0);
440 	}
441 	PROC_UNLOCK(p);
442 }
443 
444 int
445 kproc_kthread_add(void (*func)(void *), void *arg,
446             struct proc **procptr, struct thread **tdptr,
447             int flags, int pages, const char *procname, const char *fmt, ...)
448 {
449 	int error;
450 	va_list ap;
451 	char buf[100];
452 	struct thread *td;
453 
454 	if (*procptr == NULL) {
455 		error = kproc_create(func, arg,
456 		    	procptr, flags, pages, "%s", procname);
457 		if (error)
458 			return (error);
459 		td = FIRST_THREAD_IN_PROC(*procptr);
460 		if (tdptr)
461 			*tdptr = td;
462 		va_start(ap, fmt);
463 		vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
464 		va_end(ap);
465 #ifdef KTR
466 		sched_clear_tdname(td);
467 #endif
468 		return (0);
469 	}
470 	va_start(ap, fmt);
471 	vsnprintf(buf, sizeof(buf), fmt, ap);
472 	va_end(ap);
473 	error = kthread_add(func, arg, *procptr,
474 		    tdptr, flags, pages, "%s", buf);
475 	return (error);
476 }
477