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: stable/11/sys/kern/kern_kthread.c 331842 2018-03-31 13:19:27Z kib $");
29
30#include <sys/param.h>
31#include <sys/systm.h>
32#include <sys/cpuset.h>
33#include <sys/kthread.h>
34#include <sys/lock.h>
35#include <sys/mutex.h>
36#include <sys/proc.h>
37#include <sys/resourcevar.h>
38#include <sys/rwlock.h>
39#include <sys/signalvar.h>
40#include <sys/sx.h>
41#include <sys/umtx.h>
42#include <sys/unistd.h>
43#include <sys/wait.h>
44#include <sys/sched.h>
45#include <vm/vm.h>
46#include <vm/vm_extern.h>
47
48#include <machine/stdarg.h>
49
50/*
51 * Start a kernel process.  This is called after a fork() call in
52 * mi_startup() in the file kern/init_main.c.
53 *
54 * This function is used to start "internal" daemons and intended
55 * to be called from SYSINIT().
56 */
57void
58kproc_start(const void *udata)
59{
60	const struct kproc_desc	*kp = udata;
61	int error;
62
63	error = kproc_create((void (*)(void *))kp->func, NULL,
64		    kp->global_procpp, 0, 0, "%s", kp->arg0);
65	if (error)
66		panic("kproc_start: %s: error %d", kp->arg0, error);
67}
68
69/*
70 * Create a kernel process/thread/whatever.  It shares its address space
71 * with proc0 - ie: kernel only.
72 *
73 * func is the function to start.
74 * arg is the parameter to pass to function on first startup.
75 * newpp is the return value pointing to the thread's struct proc.
76 * flags are flags to fork1 (in unistd.h)
77 * fmt and following will be *printf'd into (*newpp)->p_comm (for ps, etc.).
78 */
79int
80kproc_create(void (*func)(void *), void *arg,
81    struct proc **newpp, int flags, int pages, const char *fmt, ...)
82{
83	struct fork_req fr;
84	int error;
85	va_list ap;
86	struct thread *td;
87	struct proc *p2;
88
89	if (!proc0.p_stats)
90		panic("kproc_create called too soon");
91
92	bzero(&fr, sizeof(fr));
93	fr.fr_flags = RFMEM | RFFDG | RFPROC | RFSTOPPED | flags;
94	fr.fr_pages = pages;
95	fr.fr_procp = &p2;
96	error = fork1(&thread0, &fr);
97	if (error)
98		return error;
99
100	/* save a global descriptor, if desired */
101	if (newpp != NULL)
102		*newpp = p2;
103
104	/* this is a non-swapped system process */
105	PROC_LOCK(p2);
106	td = FIRST_THREAD_IN_PROC(p2);
107	p2->p_flag |= P_SYSTEM | P_KPROC;
108	td->td_pflags |= TDP_KTHREAD;
109	mtx_lock(&p2->p_sigacts->ps_mtx);
110	p2->p_sigacts->ps_flag |= PS_NOCLDWAIT;
111	mtx_unlock(&p2->p_sigacts->ps_mtx);
112	PROC_UNLOCK(p2);
113
114	/* set up arg0 for 'ps', et al */
115	va_start(ap, fmt);
116	vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap);
117	va_end(ap);
118	/* set up arg0 for 'ps', et al */
119	va_start(ap, fmt);
120	vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
121	va_end(ap);
122#ifdef KTR
123	sched_clear_tdname(td);
124#endif
125
126	/* call the processes' main()... */
127	cpu_fork_kthread_handler(td, func, arg);
128
129	/* Avoid inheriting affinity from a random parent. */
130	cpuset_setthread(td->td_tid, cpuset_root);
131	thread_lock(td);
132	TD_SET_CAN_RUN(td);
133	sched_prio(td, PVM);
134	sched_user_prio(td, PUSER);
135
136	/* Delay putting it on the run queue until now. */
137	if (!(flags & RFSTOPPED))
138		sched_add(td, SRQ_BORING);
139	thread_unlock(td);
140
141	return 0;
142}
143
144void
145kproc_exit(int ecode)
146{
147	struct thread *td;
148	struct proc *p;
149
150	td = curthread;
151	p = td->td_proc;
152
153	/*
154	 * Reparent curthread from proc0 to init so that the zombie
155	 * is harvested.
156	 */
157	sx_xlock(&proctree_lock);
158	PROC_LOCK(p);
159	proc_reparent(p, initproc);
160	PROC_UNLOCK(p);
161	sx_xunlock(&proctree_lock);
162
163	/*
164	 * Wakeup anyone waiting for us to exit.
165	 */
166	wakeup(p);
167
168	/* Buh-bye! */
169	exit1(td, ecode, 0);
170}
171
172/*
173 * Advise a kernel process to suspend (or resume) in its main loop.
174 * Participation is voluntary.
175 */
176int
177kproc_suspend(struct proc *p, int timo)
178{
179	/*
180	 * Make sure this is indeed a system process and we can safely
181	 * use the p_siglist field.
182	 */
183	PROC_LOCK(p);
184	if ((p->p_flag & P_KPROC) == 0) {
185		PROC_UNLOCK(p);
186		return (EINVAL);
187	}
188	SIGADDSET(p->p_siglist, SIGSTOP);
189	wakeup(p);
190	return msleep(&p->p_siglist, &p->p_mtx, PPAUSE | PDROP, "suspkp", timo);
191}
192
193int
194kproc_resume(struct proc *p)
195{
196	/*
197	 * Make sure this is indeed a system process and we can safely
198	 * use the p_siglist field.
199	 */
200	PROC_LOCK(p);
201	if ((p->p_flag & P_KPROC) == 0) {
202		PROC_UNLOCK(p);
203		return (EINVAL);
204	}
205	SIGDELSET(p->p_siglist, SIGSTOP);
206	PROC_UNLOCK(p);
207	wakeup(&p->p_siglist);
208	return (0);
209}
210
211void
212kproc_suspend_check(struct proc *p)
213{
214	PROC_LOCK(p);
215	while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
216		wakeup(&p->p_siglist);
217		msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "kpsusp", 0);
218	}
219	PROC_UNLOCK(p);
220}
221
222
223/*
224 * Start a kernel thread.
225 *
226 * This function is used to start "internal" daemons and intended
227 * to be called from SYSINIT().
228 */
229
230void
231kthread_start(const void *udata)
232{
233	const struct kthread_desc	*kp = udata;
234	int error;
235
236	error = kthread_add((void (*)(void *))kp->func, NULL,
237		    NULL, kp->global_threadpp, 0, 0, "%s", kp->arg0);
238	if (error)
239		panic("kthread_start: %s: error %d", kp->arg0, error);
240}
241
242/*
243 * Create a kernel thread.  It shares its address space
244 * with proc0 - ie: kernel only.
245 *
246 * func is the function to start.
247 * arg is the parameter to pass to function on first startup.
248 * newtdp is the return value pointing to the thread's struct thread.
249 *  ** XXX fix this --> flags are flags to fork1 (in unistd.h)
250 * fmt and following will be *printf'd into (*newtd)->td_name (for ps, etc.).
251 */
252int
253kthread_add(void (*func)(void *), void *arg, struct proc *p,
254    struct thread **newtdp, int flags, int pages, const char *fmt, ...)
255{
256	va_list ap;
257	struct thread *newtd, *oldtd;
258
259	if (!proc0.p_stats)
260		panic("kthread_add called too soon");
261
262	/* If no process supplied, put it on proc0 */
263	if (p == NULL)
264		p = &proc0;
265
266	/* Initialize our new td  */
267	newtd = thread_alloc(pages);
268	if (newtd == NULL)
269		return (ENOMEM);
270
271	PROC_LOCK(p);
272	oldtd = FIRST_THREAD_IN_PROC(p);
273
274	bzero(&newtd->td_startzero,
275	    __rangeof(struct thread, td_startzero, td_endzero));
276	newtd->td_sleeptimo = 0;
277	newtd->td_vslock_sz = 0;
278	bzero(&newtd->td_si, sizeof(newtd->td_si));
279	bcopy(&oldtd->td_startcopy, &newtd->td_startcopy,
280	    __rangeof(struct thread, td_startcopy, td_endcopy));
281	newtd->td_sa = oldtd->td_sa;
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	newtd->td_proc = p;  /* needed for cpu_copy_thread */
289	/* might be further optimized for kthread */
290	cpu_copy_thread(newtd, oldtd);
291	/* put the designated function(arg) as the resume context */
292	cpu_fork_kthread_handler(newtd, func, arg);
293
294	newtd->td_pflags |= TDP_KTHREAD;
295	thread_cow_get_proc(newtd, p);
296
297	/* this code almost the same as create_thread() in kern_thr.c */
298	p->p_flag |= P_HADTHREADS;
299	thread_link(newtd, p);
300	thread_lock(oldtd);
301	/* let the scheduler know about these things. */
302	sched_fork_thread(oldtd, newtd);
303	TD_SET_CAN_RUN(newtd);
304	thread_unlock(oldtd);
305	PROC_UNLOCK(p);
306
307	tidhash_add(newtd);
308
309	/* Avoid inheriting affinity from a random parent. */
310	cpuset_setthread(newtd->td_tid, cpuset_root);
311
312	/* Delay putting it on the run queue until now. */
313	if (!(flags & RFSTOPPED)) {
314		thread_lock(newtd);
315		sched_add(newtd, SRQ_BORING);
316		thread_unlock(newtd);
317	}
318	if (newtdp)
319		*newtdp = newtd;
320	return 0;
321}
322
323void
324kthread_exit(void)
325{
326	struct proc *p;
327	struct thread *td;
328
329	td = curthread;
330	p = td->td_proc;
331
332	/* A module may be waiting for us to exit. */
333	wakeup(td);
334
335	/*
336	 * The last exiting thread in a kernel process must tear down
337	 * the whole process.
338	 */
339	rw_wlock(&tidhash_lock);
340	PROC_LOCK(p);
341	if (p->p_numthreads == 1) {
342		PROC_UNLOCK(p);
343		rw_wunlock(&tidhash_lock);
344		kproc_exit(0);
345	}
346	LIST_REMOVE(td, td_hash);
347	rw_wunlock(&tidhash_lock);
348	umtx_thread_exit(td);
349	tdsigcleanup(td);
350	PROC_SLOCK(p);
351	thread_exit();
352}
353
354/*
355 * Advise a kernel process to suspend (or resume) in its main loop.
356 * Participation is voluntary.
357 */
358int
359kthread_suspend(struct thread *td, int timo)
360{
361	struct proc *p;
362
363	p = td->td_proc;
364
365	/*
366	 * td_pflags should not be read by any thread other than
367	 * curthread, but as long as this flag is invariant during the
368	 * thread's lifetime, it is OK to check its state.
369	 */
370	if ((td->td_pflags & TDP_KTHREAD) == 0)
371		return (EINVAL);
372
373	/*
374	 * The caller of the primitive should have already checked that the
375	 * thread is up and running, thus not being blocked by other
376	 * conditions.
377	 */
378	PROC_LOCK(p);
379	thread_lock(td);
380	td->td_flags |= TDF_KTH_SUSP;
381	thread_unlock(td);
382	return (msleep(&td->td_flags, &p->p_mtx, PPAUSE | PDROP, "suspkt",
383	    timo));
384}
385
386/*
387 * Resume a thread previously put asleep with kthread_suspend().
388 */
389int
390kthread_resume(struct thread *td)
391{
392	struct proc *p;
393
394	p = td->td_proc;
395
396	/*
397	 * td_pflags should not be read by any thread other than
398	 * curthread, but as long as this flag is invariant during the
399	 * thread's lifetime, it is OK to check its state.
400	 */
401	if ((td->td_pflags & TDP_KTHREAD) == 0)
402		return (EINVAL);
403
404	PROC_LOCK(p);
405	thread_lock(td);
406	td->td_flags &= ~TDF_KTH_SUSP;
407	thread_unlock(td);
408	wakeup(&td->td_flags);
409	PROC_UNLOCK(p);
410	return (0);
411}
412
413/*
414 * Used by the thread to poll as to whether it should yield/sleep
415 * and notify the caller that is has happened.
416 */
417void
418kthread_suspend_check(void)
419{
420	struct proc *p;
421	struct thread *td;
422
423	td = curthread;
424	p = td->td_proc;
425
426	if ((td->td_pflags & TDP_KTHREAD) == 0)
427		panic("%s: curthread is not a valid kthread", __func__);
428
429	/*
430	 * As long as the double-lock protection is used when accessing the
431	 * TDF_KTH_SUSP flag, synchronizing the read operation via proc mutex
432	 * is fine.
433	 */
434	PROC_LOCK(p);
435	while (td->td_flags & TDF_KTH_SUSP) {
436		wakeup(&td->td_flags);
437		msleep(&td->td_flags, &p->p_mtx, PPAUSE, "ktsusp", 0);
438	}
439	PROC_UNLOCK(p);
440}
441
442int
443kproc_kthread_add(void (*func)(void *), void *arg,
444            struct proc **procptr, struct thread **tdptr,
445            int flags, int pages, const char *procname, const char *fmt, ...)
446{
447	int error;
448	va_list ap;
449	char buf[100];
450	struct thread *td;
451
452	if (*procptr == NULL) {
453		error = kproc_create(func, arg,
454		    	procptr, flags, pages, "%s", procname);
455		if (error)
456			return (error);
457		td = FIRST_THREAD_IN_PROC(*procptr);
458		if (tdptr)
459			*tdptr = td;
460		va_start(ap, fmt);
461		vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
462		va_end(ap);
463#ifdef KTR
464		sched_clear_tdname(td);
465#endif
466		return (0);
467	}
468	va_start(ap, fmt);
469	vsnprintf(buf, sizeof(buf), fmt, ap);
470	va_end(ap);
471	error = kthread_add(func, arg, *procptr,
472		    tdptr, flags, pages, "%s", buf);
473	return (error);
474}
475