1 /*-
2 * Copyright (C) 2001 Julian Elischer <julian@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(s), this list of conditions and the following disclaimer as
10 * the first lines of this file unmodified other than the possible
11 * addition of one or more copyright notices.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice(s), 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 COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
17 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
20 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
22 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
23 * 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 SUCH
26 * DAMAGE.
27 */
28
29 #include "opt_witness.h"
30 #include "opt_kdtrace.h"
31 #include "opt_hwpmc_hooks.h"
32
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35
36 #include <sys/param.h>
37 #include <sys/systm.h>
38 #include <sys/kernel.h>
39 #include <sys/lock.h>
40 #include <sys/mutex.h>
41 #include <sys/proc.h>
42 #include <sys/rangelock.h>
43 #include <sys/resourcevar.h>
44 #include <sys/sdt.h>
45 #include <sys/smp.h>
46 #include <sys/sched.h>
47 #include <sys/sleepqueue.h>
48 #include <sys/selinfo.h>
49 #include <sys/syscallsubr.h>
50 #include <sys/sysent.h>
51 #include <sys/turnstile.h>
52 #include <sys/ktr.h>
53 #include <sys/rwlock.h>
54 #include <sys/umtx.h>
55 #include <sys/cpuset.h>
56 #ifdef HWPMC_HOOKS
57 #include <sys/pmckern.h>
58 #endif
59
60 #include <security/audit/audit.h>
61
62 #include <vm/vm.h>
63 #include <vm/vm_extern.h>
64 #include <vm/uma.h>
65 #include <sys/eventhandler.h>
66
67 SDT_PROVIDER_DECLARE(proc);
68 SDT_PROBE_DEFINE(proc, , , lwp__exit);
69
70 /*
71 * thread related storage.
72 */
73 static uma_zone_t thread_zone;
74
75 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads);
76 static struct mtx zombie_lock;
77 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN);
78
79 static void thread_zombie(struct thread *);
80 static int thread_unsuspend_one(struct thread *td, struct proc *p,
81 bool boundary);
82
83 #define TID_BUFFER_SIZE 1024
84
85 struct mtx tid_lock;
86 static struct unrhdr *tid_unrhdr;
87 static lwpid_t tid_buffer[TID_BUFFER_SIZE];
88 static int tid_head, tid_tail;
89 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash");
90
91 struct tidhashhead *tidhashtbl;
92 u_long tidhash;
93 struct rwlock tidhash_lock;
94
95 static lwpid_t
96 tid_alloc(void)
97 {
98 lwpid_t tid;
99
100 tid = alloc_unr(tid_unrhdr);
101 if (tid != -1)
102 return (tid);
103 mtx_lock(&tid_lock);
104 if (tid_head == tid_tail) {
105 mtx_unlock(&tid_lock);
106 return (-1);
107 }
108 tid = tid_buffer[tid_head];
109 tid_head = (tid_head + 1) % TID_BUFFER_SIZE;
110 mtx_unlock(&tid_lock);
111 return (tid);
112 }
113
114 static void
115 tid_free(lwpid_t tid)
116 {
117 lwpid_t tmp_tid = -1;
118
119 mtx_lock(&tid_lock);
120 if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) {
121 tmp_tid = tid_buffer[tid_head];
122 tid_head = (tid_head + 1) % TID_BUFFER_SIZE;
123 }
124 tid_buffer[tid_tail] = tid;
125 tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE;
126 mtx_unlock(&tid_lock);
127 if (tmp_tid != -1)
128 free_unr(tid_unrhdr, tmp_tid);
129 }
130
131 /*
132 * Prepare a thread for use.
133 */
134 static int
135 thread_ctor(void *mem, int size, void *arg, int flags)
136 {
137 struct thread *td;
138
139 td = (struct thread *)mem;
140 td->td_state = TDS_INACTIVE;
141 td->td_oncpu = NOCPU;
142
143 td->td_tid = tid_alloc();
144
145 /*
146 * Note that td_critnest begins life as 1 because the thread is not
147 * running and is thereby implicitly waiting to be on the receiving
148 * end of a context switch.
149 */
150 td->td_critnest = 1;
151 td->td_lend_user_pri = PRI_MAX;
152 EVENTHANDLER_INVOKE(thread_ctor, td);
153 #ifdef AUDIT
154 audit_thread_alloc(td);
155 #endif
156 umtx_thread_alloc(td);
157 return (0);
158 }
159
160 /*
161 * Reclaim a thread after use.
162 */
163 static void
164 thread_dtor(void *mem, int size, void *arg)
165 {
166 struct thread *td;
167
168 td = (struct thread *)mem;
169
170 #ifdef INVARIANTS
171 /* Verify that this thread is in a safe state to free. */
172 switch (td->td_state) {
173 case TDS_INHIBITED:
174 case TDS_RUNNING:
175 case TDS_CAN_RUN:
176 case TDS_RUNQ:
177 /*
178 * We must never unlink a thread that is in one of
179 * these states, because it is currently active.
180 */
181 panic("bad state for thread unlinking");
182 /* NOTREACHED */
183 case TDS_INACTIVE:
184 break;
185 default:
186 panic("bad thread state");
187 /* NOTREACHED */
188 }
189 #endif
190 #ifdef AUDIT
191 audit_thread_free(td);
192 #endif
193 /* Free all OSD associated to this thread. */
194 osd_thread_exit(td);
195
196 EVENTHANDLER_INVOKE(thread_dtor, td);
197 tid_free(td->td_tid);
198 }
199
200 /*
201 * Initialize type-stable parts of a thread (when newly created).
202 */
203 static int
204 thread_init(void *mem, int size, int flags)
205 {
206 struct thread *td;
207
208 td = (struct thread *)mem;
209
210 td->td_sleepqueue = sleepq_alloc();
211 td->td_turnstile = turnstile_alloc();
212 td->td_rlqe = NULL;
213 EVENTHANDLER_INVOKE(thread_init, td);
214 td->td_sched = (struct td_sched *)&td[1];
215 umtx_thread_init(td);
216 td->td_kstack = 0;
217 td->td_sel = NULL;
218 return (0);
219 }
220
221 /*
222 * Tear down type-stable parts of a thread (just before being discarded).
223 */
224 static void
225 thread_fini(void *mem, int size)
226 {
227 struct thread *td;
228
229 td = (struct thread *)mem;
230 EVENTHANDLER_INVOKE(thread_fini, td);
231 rlqentry_free(td->td_rlqe);
232 turnstile_free(td->td_turnstile);
233 sleepq_free(td->td_sleepqueue);
234 umtx_thread_fini(td);
235 seltdfini(td);
236 }
237
238 /*
239 * For a newly created process,
240 * link up all the structures and its initial threads etc.
241 * called from:
242 * {arch}/{arch}/machdep.c ia64_init(), init386() etc.
243 * proc_dtor() (should go away)
244 * proc_init()
245 */
246 void
247 proc_linkup0(struct proc *p, struct thread *td)
248 {
249 TAILQ_INIT(&p->p_threads); /* all threads in proc */
250 proc_linkup(p, td);
251 }
252
253 void
254 proc_linkup(struct proc *p, struct thread *td)
255 {
256
257 sigqueue_init(&p->p_sigqueue, p);
258 p->p_ksi = ksiginfo_alloc(1);
259 if (p->p_ksi != NULL) {
260 /* XXX p_ksi may be null if ksiginfo zone is not ready */
261 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS;
262 }
263 LIST_INIT(&p->p_mqnotifier);
264 p->p_numthreads = 0;
265 thread_link(td, p);
266 }
267
268 /*
269 * Initialize global thread allocation resources.
270 */
271 void
272 threadinit(void)
273 {
274
275 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
276
277 /*
278 * pid_max cannot be greater than PID_MAX.
279 * leave one number for thread0.
280 */
281 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock);
282
283 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
284 thread_ctor, thread_dtor, thread_init, thread_fini,
285 16 - 1, UMA_ZONE_NOFREE);
286 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash);
287 rw_init(&tidhash_lock, "tidhash");
288 }
289
290 /*
291 * Place an unused thread on the zombie list.
292 * Use the slpq as that must be unused by now.
293 */
294 void
295 thread_zombie(struct thread *td)
296 {
297 mtx_lock_spin(&zombie_lock);
298 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq);
299 mtx_unlock_spin(&zombie_lock);
300 }
301
302 /*
303 * Release a thread that has exited after cpu_throw().
304 */
305 void
306 thread_stash(struct thread *td)
307 {
308 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1);
309 thread_zombie(td);
310 }
311
312 /*
313 * Reap zombie resources.
314 */
315 void
316 thread_reap(void)
317 {
318 struct thread *td_first, *td_next;
319
320 /*
321 * Don't even bother to lock if none at this instant,
322 * we really don't care about the next instant.
323 */
324 if (!TAILQ_EMPTY(&zombie_threads)) {
325 mtx_lock_spin(&zombie_lock);
326 td_first = TAILQ_FIRST(&zombie_threads);
327 if (td_first)
328 TAILQ_INIT(&zombie_threads);
329 mtx_unlock_spin(&zombie_lock);
330 while (td_first) {
331 td_next = TAILQ_NEXT(td_first, td_slpq);
332 if (td_first->td_ucred)
333 crfree(td_first->td_ucred);
334 thread_free(td_first);
335 td_first = td_next;
336 }
337 }
338 }
339
340 /*
341 * Allocate a thread.
342 */
343 struct thread *
344 thread_alloc(int pages)
345 {
346 struct thread *td;
347
348 thread_reap(); /* check if any zombies to get */
349
350 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK);
351 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
352 if (!vm_thread_new(td, pages)) {
353 uma_zfree(thread_zone, td);
354 return (NULL);
355 }
356 cpu_thread_alloc(td);
357 return (td);
358 }
359
360 int
361 thread_alloc_stack(struct thread *td, int pages)
362 {
363
364 KASSERT(td->td_kstack == 0,
365 ("thread_alloc_stack called on a thread with kstack"));
366 if (!vm_thread_new(td, pages))
367 return (0);
368 cpu_thread_alloc(td);
369 return (1);
370 }
371
372 /*
373 * Deallocate a thread.
374 */
375 void
376 thread_free(struct thread *td)
377 {
378
379 lock_profile_thread_exit(td);
380 if (td->td_cpuset)
381 cpuset_rel(td->td_cpuset);
382 td->td_cpuset = NULL;
383 cpu_thread_free(td);
384 if (td->td_kstack != 0)
385 vm_thread_dispose(td);
386 callout_drain(&td->td_slpcallout);
387 uma_zfree(thread_zone, td);
388 }
389
390 /*
391 * Discard the current thread and exit from its context.
392 * Always called with scheduler locked.
393 *
394 * Because we can't free a thread while we're operating under its context,
395 * push the current thread into our CPU's deadthread holder. This means
396 * we needn't worry about someone else grabbing our context before we
397 * do a cpu_throw().
398 */
399 void
400 thread_exit(void)
401 {
402 uint64_t runtime, new_switchtime;
403 struct thread *td;
404 struct thread *td2;
405 struct proc *p;
406 int wakeup_swapper;
407
408 td = curthread;
409 p = td->td_proc;
410
411 PROC_SLOCK_ASSERT(p, MA_OWNED);
412 mtx_assert(&Giant, MA_NOTOWNED);
413
414 PROC_LOCK_ASSERT(p, MA_OWNED);
415 KASSERT(p != NULL, ("thread exiting without a process"));
416 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
417 (long)p->p_pid, td->td_name);
418 SDT_PROBE0(proc, , , lwp__exit);
419 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
420
421 /*
422 * drop FPU & debug register state storage, or any other
423 * architecture specific resources that
424 * would not be on a new untouched process.
425 */
426 cpu_thread_exit(td);
427
428 /*
429 * The last thread is left attached to the process
430 * So that the whole bundle gets recycled. Skip
431 * all this stuff if we never had threads.
432 * EXIT clears all sign of other threads when
433 * it goes to single threading, so the last thread always
434 * takes the short path.
435 */
436 if (p->p_flag & P_HADTHREADS) {
437 if (p->p_numthreads > 1) {
438 atomic_add_int(&td->td_proc->p_exitthreads, 1);
439 thread_unlink(td);
440 td2 = FIRST_THREAD_IN_PROC(p);
441 sched_exit_thread(td2, td);
442
443 /*
444 * The test below is NOT true if we are the
445 * sole exiting thread. P_STOPPED_SINGLE is unset
446 * in exit1() after it is the only survivor.
447 */
448 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
449 if (p->p_numthreads == p->p_suspcount) {
450 thread_lock(p->p_singlethread);
451 wakeup_swapper = thread_unsuspend_one(
452 p->p_singlethread, p, false);
453 thread_unlock(p->p_singlethread);
454 if (wakeup_swapper)
455 kick_proc0();
456 }
457 }
458
459 PCPU_SET(deadthread, td);
460 } else {
461 /*
462 * The last thread is exiting.. but not through exit()
463 */
464 panic ("thread_exit: Last thread exiting on its own");
465 }
466 }
467 #ifdef HWPMC_HOOKS
468 /*
469 * If this thread is part of a process that is being tracked by hwpmc(4),
470 * inform the module of the thread's impending exit.
471 */
472 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
473 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
474 #endif
475 PROC_UNLOCK(p);
476 PROC_STATLOCK(p);
477 thread_lock(td);
478 PROC_SUNLOCK(p);
479
480 /* Do the same timestamp bookkeeping that mi_switch() would do. */
481 new_switchtime = cpu_ticks();
482 runtime = new_switchtime - PCPU_GET(switchtime);
483 td->td_runtime += runtime;
484 td->td_incruntime += runtime;
485 PCPU_SET(switchtime, new_switchtime);
486 PCPU_SET(switchticks, ticks);
487 PCPU_INC(cnt.v_swtch);
488
489 /* Save our resource usage in our process. */
490 td->td_ru.ru_nvcsw++;
491 ruxagg(p, td);
492 rucollect(&p->p_ru, &td->td_ru);
493 PROC_STATUNLOCK(p);
494
495 td->td_state = TDS_INACTIVE;
496 #ifdef WITNESS
497 witness_thread_exit(td);
498 #endif
499 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
500 sched_throw(td);
501 panic("I'm a teapot!");
502 /* NOTREACHED */
503 }
504
505 /*
506 * Do any thread specific cleanups that may be needed in wait()
507 * called with Giant, proc and schedlock not held.
508 */
509 void
510 thread_wait(struct proc *p)
511 {
512 struct thread *td;
513
514 mtx_assert(&Giant, MA_NOTOWNED);
515 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()"));
516 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking"));
517 td = FIRST_THREAD_IN_PROC(p);
518 /* Lock the last thread so we spin until it exits cpu_throw(). */
519 thread_lock(td);
520 thread_unlock(td);
521 lock_profile_thread_exit(td);
522 cpuset_rel(td->td_cpuset);
523 td->td_cpuset = NULL;
524 cpu_thread_clean(td);
525 crfree(td->td_ucred);
526 callout_drain(&td->td_slpcallout);
527 thread_reap(); /* check for zombie threads etc. */
528 }
529
530 /*
531 * Link a thread to a process.
532 * set up anything that needs to be initialized for it to
533 * be used by the process.
534 */
535 void
536 thread_link(struct thread *td, struct proc *p)
537 {
538
539 /*
540 * XXX This can't be enabled because it's called for proc0 before
541 * its lock has been created.
542 * PROC_LOCK_ASSERT(p, MA_OWNED);
543 */
544 td->td_state = TDS_INACTIVE;
545 td->td_proc = p;
546 td->td_flags = TDF_INMEM;
547
548 LIST_INIT(&td->td_contested);
549 LIST_INIT(&td->td_lprof[0]);
550 LIST_INIT(&td->td_lprof[1]);
551 sigqueue_init(&td->td_sigqueue, p);
552 callout_init(&td->td_slpcallout, 1);
553 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist);
554 p->p_numthreads++;
555 }
556
557 /*
558 * Called from:
559 * thread_exit()
560 */
561 void
562 thread_unlink(struct thread *td)
563 {
564 struct proc *p = td->td_proc;
565
566 PROC_LOCK_ASSERT(p, MA_OWNED);
567 TAILQ_REMOVE(&p->p_threads, td, td_plist);
568 p->p_numthreads--;
569 /* could clear a few other things here */
570 /* Must NOT clear links to proc! */
571 }
572
573 static int
574 calc_remaining(struct proc *p, int mode)
575 {
576 int remaining;
577
578 PROC_LOCK_ASSERT(p, MA_OWNED);
579 PROC_SLOCK_ASSERT(p, MA_OWNED);
580 if (mode == SINGLE_EXIT)
581 remaining = p->p_numthreads;
582 else if (mode == SINGLE_BOUNDARY)
583 remaining = p->p_numthreads - p->p_boundary_count;
584 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC)
585 remaining = p->p_numthreads - p->p_suspcount;
586 else
587 panic("calc_remaining: wrong mode %d", mode);
588 return (remaining);
589 }
590
591 static int
592 remain_for_mode(int mode)
593 {
594
595 return (mode == SINGLE_ALLPROC ? 0 : 1);
596 }
597
598 static int
599 weed_inhib(int mode, struct thread *td2, struct proc *p)
600 {
601 int wakeup_swapper;
602
603 PROC_LOCK_ASSERT(p, MA_OWNED);
604 PROC_SLOCK_ASSERT(p, MA_OWNED);
605 THREAD_LOCK_ASSERT(td2, MA_OWNED);
606
607 wakeup_swapper = 0;
608 switch (mode) {
609 case SINGLE_EXIT:
610 if (TD_IS_SUSPENDED(td2))
611 wakeup_swapper |= thread_unsuspend_one(td2, p, true);
612 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0)
613 wakeup_swapper |= sleepq_abort(td2, EINTR);
614 break;
615 case SINGLE_BOUNDARY:
616 case SINGLE_NO_EXIT:
617 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0)
618 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
619 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0)
620 wakeup_swapper |= sleepq_abort(td2, ERESTART);
621 break;
622 case SINGLE_ALLPROC:
623 /*
624 * ALLPROC suspend tries to avoid spurious EINTR for
625 * threads sleeping interruptable, by suspending the
626 * thread directly, similarly to sig_suspend_threads().
627 * Since such sleep is not performed at the user
628 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP
629 * is used to avoid immediate un-suspend.
630 */
631 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY |
632 TDF_ALLPROCSUSP)) == 0)
633 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
634 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) {
635 if ((td2->td_flags & TDF_SBDRY) == 0) {
636 thread_suspend_one(td2);
637 td2->td_flags |= TDF_ALLPROCSUSP;
638 } else {
639 wakeup_swapper |= sleepq_abort(td2, ERESTART);
640 }
641 }
642 break;
643 }
644 return (wakeup_swapper);
645 }
646
647 /*
648 * Enforce single-threading.
649 *
650 * Returns 1 if the caller must abort (another thread is waiting to
651 * exit the process or similar). Process is locked!
652 * Returns 0 when you are successfully the only thread running.
653 * A process has successfully single threaded in the suspend mode when
654 * There are no threads in user mode. Threads in the kernel must be
655 * allowed to continue until they get to the user boundary. They may even
656 * copy out their return values and data before suspending. They may however be
657 * accelerated in reaching the user boundary as we will wake up
658 * any sleeping threads that are interruptable. (PCATCH).
659 */
660 int
661 thread_single(struct proc *p, int mode)
662 {
663 struct thread *td;
664 struct thread *td2;
665 int remaining, wakeup_swapper;
666
667 td = curthread;
668 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
669 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
670 ("invalid mode %d", mode));
671 /*
672 * If allowing non-ALLPROC singlethreading for non-curproc
673 * callers, calc_remaining() and remain_for_mode() should be
674 * adjusted to also account for td->td_proc != p. For now
675 * this is not implemented because it is not used.
676 */
677 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) ||
678 (mode != SINGLE_ALLPROC && td->td_proc == p),
679 ("mode %d proc %p curproc %p", mode, p, td->td_proc));
680 mtx_assert(&Giant, MA_NOTOWNED);
681 PROC_LOCK_ASSERT(p, MA_OWNED);
682
683 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC)
684 return (0);
685
686 /* Is someone already single threading? */
687 if (p->p_singlethread != NULL && p->p_singlethread != td)
688 return (1);
689
690 if (mode == SINGLE_EXIT) {
691 p->p_flag |= P_SINGLE_EXIT;
692 p->p_flag &= ~P_SINGLE_BOUNDARY;
693 } else {
694 p->p_flag &= ~P_SINGLE_EXIT;
695 if (mode == SINGLE_BOUNDARY)
696 p->p_flag |= P_SINGLE_BOUNDARY;
697 else
698 p->p_flag &= ~P_SINGLE_BOUNDARY;
699 }
700 if (mode == SINGLE_ALLPROC)
701 p->p_flag |= P_TOTAL_STOP;
702 p->p_flag |= P_STOPPED_SINGLE;
703 PROC_SLOCK(p);
704 p->p_singlethread = td;
705 remaining = calc_remaining(p, mode);
706 while (remaining != remain_for_mode(mode)) {
707 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE)
708 goto stopme;
709 wakeup_swapper = 0;
710 FOREACH_THREAD_IN_PROC(p, td2) {
711 if (td2 == td)
712 continue;
713 thread_lock(td2);
714 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK;
715 if (TD_IS_INHIBITED(td2)) {
716 wakeup_swapper |= weed_inhib(mode, td2, p);
717 #ifdef SMP
718 } else if (TD_IS_RUNNING(td2) && td != td2) {
719 forward_signal(td2);
720 #endif
721 }
722 thread_unlock(td2);
723 }
724 if (wakeup_swapper)
725 kick_proc0();
726 remaining = calc_remaining(p, mode);
727
728 /*
729 * Maybe we suspended some threads.. was it enough?
730 */
731 if (remaining == remain_for_mode(mode))
732 break;
733
734 stopme:
735 /*
736 * Wake us up when everyone else has suspended.
737 * In the mean time we suspend as well.
738 */
739 thread_suspend_switch(td, p);
740 remaining = calc_remaining(p, mode);
741 }
742 if (mode == SINGLE_EXIT) {
743 /*
744 * Convert the process to an unthreaded process. The
745 * SINGLE_EXIT is called by exit1() or execve(), in
746 * both cases other threads must be retired.
747 */
748 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads"));
749 p->p_singlethread = NULL;
750 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS);
751
752 /*
753 * Wait for any remaining threads to exit cpu_throw().
754 */
755 while (p->p_exitthreads != 0) {
756 PROC_SUNLOCK(p);
757 PROC_UNLOCK(p);
758 sched_relinquish(td);
759 PROC_LOCK(p);
760 PROC_SLOCK(p);
761 }
762 } else if (mode == SINGLE_BOUNDARY) {
763 /*
764 * Wait until all suspended threads are removed from
765 * the processors. The thread_suspend_check()
766 * increments p_boundary_count while it is still
767 * running, which makes it possible for the execve()
768 * to destroy vmspace while our other threads are
769 * still using the address space.
770 *
771 * We lock the thread, which is only allowed to
772 * succeed after context switch code finished using
773 * the address space.
774 */
775 FOREACH_THREAD_IN_PROC(p, td2) {
776 if (td2 == td)
777 continue;
778 thread_lock(td2);
779 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0,
780 ("td %p not on boundary", td2));
781 KASSERT(TD_IS_SUSPENDED(td2),
782 ("td %p is not suspended", td2));
783 thread_unlock(td2);
784 }
785 }
786 PROC_SUNLOCK(p);
787 return (0);
788 }
789
790 bool
791 thread_suspend_check_needed(void)
792 {
793 struct proc *p;
794 struct thread *td;
795
796 td = curthread;
797 p = td->td_proc;
798 PROC_LOCK_ASSERT(p, MA_OWNED);
799 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 &&
800 (td->td_dbgflags & TDB_SUSPEND) != 0));
801 }
802
803 /*
804 * Called in from locations that can safely check to see
805 * whether we have to suspend or at least throttle for a
806 * single-thread event (e.g. fork).
807 *
808 * Such locations include userret().
809 * If the "return_instead" argument is non zero, the thread must be able to
810 * accept 0 (caller may continue), or 1 (caller must abort) as a result.
811 *
812 * The 'return_instead' argument tells the function if it may do a
813 * thread_exit() or suspend, or whether the caller must abort and back
814 * out instead.
815 *
816 * If the thread that set the single_threading request has set the
817 * P_SINGLE_EXIT bit in the process flags then this call will never return
818 * if 'return_instead' is false, but will exit.
819 *
820 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0
821 *---------------+--------------------+---------------------
822 * 0 | returns 0 | returns 0 or 1
823 * | when ST ends | immediately
824 *---------------+--------------------+---------------------
825 * 1 | thread exits | returns 1
826 * | | immediately
827 * 0 = thread_exit() or suspension ok,
828 * other = return error instead of stopping the thread.
829 *
830 * While a full suspension is under effect, even a single threading
831 * thread would be suspended if it made this call (but it shouldn't).
832 * This call should only be made from places where
833 * thread_exit() would be safe as that may be the outcome unless
834 * return_instead is set.
835 */
836 int
837 thread_suspend_check(int return_instead)
838 {
839 struct thread *td;
840 struct proc *p;
841 int wakeup_swapper;
842
843 td = curthread;
844 p = td->td_proc;
845 mtx_assert(&Giant, MA_NOTOWNED);
846 PROC_LOCK_ASSERT(p, MA_OWNED);
847 while (thread_suspend_check_needed()) {
848 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
849 KASSERT(p->p_singlethread != NULL,
850 ("singlethread not set"));
851 /*
852 * The only suspension in action is a
853 * single-threading. Single threader need not stop.
854 * It is safe to access p->p_singlethread unlocked
855 * because it can only be set to our address by us.
856 */
857 if (p->p_singlethread == td)
858 return (0); /* Exempt from stopping. */
859 }
860 if ((p->p_flag & P_SINGLE_EXIT) && return_instead)
861 return (EINTR);
862
863 /* Should we goto user boundary if we didn't come from there? */
864 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
865 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
866 return (ERESTART);
867
868 /*
869 * Ignore suspend requests if they are deferred.
870 */
871 if ((td->td_flags & TDF_SBDRY) != 0) {
872 KASSERT(return_instead,
873 ("TDF_SBDRY set for unsafe thread_suspend_check"));
874 return (0);
875 }
876
877 /*
878 * If the process is waiting for us to exit,
879 * this thread should just suicide.
880 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
881 */
882 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
883 PROC_UNLOCK(p);
884
885 /*
886 * Allow Linux emulation layer to do some work
887 * before thread suicide.
888 */
889 if (__predict_false(p->p_sysent->sv_thread_detach != NULL))
890 (p->p_sysent->sv_thread_detach)(td);
891 kern_thr_exit(td);
892 panic("stopped thread did not exit");
893 }
894
895 PROC_SLOCK(p);
896 thread_stopped(p);
897 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
898 if (p->p_numthreads == p->p_suspcount + 1) {
899 thread_lock(p->p_singlethread);
900 wakeup_swapper = thread_unsuspend_one(
901 p->p_singlethread, p, false);
902 thread_unlock(p->p_singlethread);
903 if (wakeup_swapper)
904 kick_proc0();
905 }
906 }
907 PROC_UNLOCK(p);
908 thread_lock(td);
909 /*
910 * When a thread suspends, it just
911 * gets taken off all queues.
912 */
913 thread_suspend_one(td);
914 if (return_instead == 0) {
915 p->p_boundary_count++;
916 td->td_flags |= TDF_BOUNDARY;
917 }
918 PROC_SUNLOCK(p);
919 mi_switch(SW_INVOL | SWT_SUSPEND, NULL);
920 thread_unlock(td);
921 PROC_LOCK(p);
922 }
923 return (0);
924 }
925
926 void
927 thread_suspend_switch(struct thread *td, struct proc *p)
928 {
929
930 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
931 PROC_LOCK_ASSERT(p, MA_OWNED);
932 PROC_SLOCK_ASSERT(p, MA_OWNED);
933 /*
934 * We implement thread_suspend_one in stages here to avoid
935 * dropping the proc lock while the thread lock is owned.
936 */
937 if (p == td->td_proc) {
938 thread_stopped(p);
939 p->p_suspcount++;
940 }
941 PROC_UNLOCK(p);
942 thread_lock(td);
943 td->td_flags &= ~TDF_NEEDSUSPCHK;
944 TD_SET_SUSPENDED(td);
945 sched_sleep(td, 0);
946 PROC_SUNLOCK(p);
947 DROP_GIANT();
948 mi_switch(SW_VOL | SWT_SUSPEND, NULL);
949 thread_unlock(td);
950 PICKUP_GIANT();
951 PROC_LOCK(p);
952 PROC_SLOCK(p);
953 }
954
955 void
956 thread_suspend_one(struct thread *td)
957 {
958 struct proc *p;
959
960 p = td->td_proc;
961 PROC_SLOCK_ASSERT(p, MA_OWNED);
962 THREAD_LOCK_ASSERT(td, MA_OWNED);
963 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
964 p->p_suspcount++;
965 td->td_flags &= ~TDF_NEEDSUSPCHK;
966 TD_SET_SUSPENDED(td);
967 sched_sleep(td, 0);
968 }
969
970 static int
971 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary)
972 {
973
974 THREAD_LOCK_ASSERT(td, MA_OWNED);
975 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
976 TD_CLR_SUSPENDED(td);
977 td->td_flags &= ~TDF_ALLPROCSUSP;
978 if (td->td_proc == p) {
979 PROC_SLOCK_ASSERT(p, MA_OWNED);
980 p->p_suspcount--;
981 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) {
982 td->td_flags &= ~TDF_BOUNDARY;
983 p->p_boundary_count--;
984 }
985 }
986 return (setrunnable(td));
987 }
988
989 /*
990 * Allow all threads blocked by single threading to continue running.
991 */
992 void
993 thread_unsuspend(struct proc *p)
994 {
995 struct thread *td;
996 int wakeup_swapper;
997
998 PROC_LOCK_ASSERT(p, MA_OWNED);
999 PROC_SLOCK_ASSERT(p, MA_OWNED);
1000 wakeup_swapper = 0;
1001 if (!P_SHOULDSTOP(p)) {
1002 FOREACH_THREAD_IN_PROC(p, td) {
1003 thread_lock(td);
1004 if (TD_IS_SUSPENDED(td)) {
1005 wakeup_swapper |= thread_unsuspend_one(td, p,
1006 true);
1007 }
1008 thread_unlock(td);
1009 }
1010 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
1011 p->p_numthreads == p->p_suspcount) {
1012 /*
1013 * Stopping everything also did the job for the single
1014 * threading request. Now we've downgraded to single-threaded,
1015 * let it continue.
1016 */
1017 if (p->p_singlethread->td_proc == p) {
1018 thread_lock(p->p_singlethread);
1019 wakeup_swapper = thread_unsuspend_one(
1020 p->p_singlethread, p, false);
1021 thread_unlock(p->p_singlethread);
1022 }
1023 }
1024 if (wakeup_swapper)
1025 kick_proc0();
1026 }
1027
1028 /*
1029 * End the single threading mode..
1030 */
1031 void
1032 thread_single_end(struct proc *p, int mode)
1033 {
1034 struct thread *td;
1035 int wakeup_swapper;
1036
1037 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
1038 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
1039 ("invalid mode %d", mode));
1040 PROC_LOCK_ASSERT(p, MA_OWNED);
1041 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) ||
1042 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0),
1043 ("mode %d does not match P_TOTAL_STOP", mode));
1044 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread,
1045 ("thread_single_end from other thread %p %p",
1046 curthread, p->p_singlethread));
1047 KASSERT(mode != SINGLE_BOUNDARY ||
1048 (p->p_flag & P_SINGLE_BOUNDARY) != 0,
1049 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag));
1050 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY |
1051 P_TOTAL_STOP);
1052 PROC_SLOCK(p);
1053 p->p_singlethread = NULL;
1054 wakeup_swapper = 0;
1055 /*
1056 * If there are other threads they may now run,
1057 * unless of course there is a blanket 'stop order'
1058 * on the process. The single threader must be allowed
1059 * to continue however as this is a bad place to stop.
1060 */
1061 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) {
1062 FOREACH_THREAD_IN_PROC(p, td) {
1063 thread_lock(td);
1064 if (TD_IS_SUSPENDED(td)) {
1065 wakeup_swapper |= thread_unsuspend_one(td, p,
1066 mode == SINGLE_BOUNDARY);
1067 }
1068 thread_unlock(td);
1069 }
1070 }
1071 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0,
1072 ("inconsistent boundary count %d", p->p_boundary_count));
1073 PROC_SUNLOCK(p);
1074 if (wakeup_swapper)
1075 kick_proc0();
1076 }
1077
1078 struct thread *
1079 thread_find(struct proc *p, lwpid_t tid)
1080 {
1081 struct thread *td;
1082
1083 PROC_LOCK_ASSERT(p, MA_OWNED);
1084 FOREACH_THREAD_IN_PROC(p, td) {
1085 if (td->td_tid == tid)
1086 break;
1087 }
1088 return (td);
1089 }
1090
1091 /* Locate a thread by number; return with proc lock held. */
1092 struct thread *
1093 tdfind(lwpid_t tid, pid_t pid)
1094 {
1095 #define RUN_THRESH 16
1096 struct thread *td;
1097 int run = 0;
1098
1099 rw_rlock(&tidhash_lock);
1100 LIST_FOREACH(td, TIDHASH(tid), td_hash) {
1101 if (td->td_tid == tid) {
1102 if (pid != -1 && td->td_proc->p_pid != pid) {
1103 td = NULL;
1104 break;
1105 }
1106 PROC_LOCK(td->td_proc);
1107 if (td->td_proc->p_state == PRS_NEW) {
1108 PROC_UNLOCK(td->td_proc);
1109 td = NULL;
1110 break;
1111 }
1112 if (run > RUN_THRESH) {
1113 if (rw_try_upgrade(&tidhash_lock)) {
1114 LIST_REMOVE(td, td_hash);
1115 LIST_INSERT_HEAD(TIDHASH(td->td_tid),
1116 td, td_hash);
1117 rw_wunlock(&tidhash_lock);
1118 return (td);
1119 }
1120 }
1121 break;
1122 }
1123 run++;
1124 }
1125 rw_runlock(&tidhash_lock);
1126 return (td);
1127 }
1128
1129 void
1130 tidhash_add(struct thread *td)
1131 {
1132 rw_wlock(&tidhash_lock);
1133 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
1134 rw_wunlock(&tidhash_lock);
1135 }
1136
1137 void
1138 tidhash_remove(struct thread *td)
1139 {
1140 rw_wlock(&tidhash_lock);
1141 LIST_REMOVE(td, td_hash);
1142 rw_wunlock(&tidhash_lock);
1143 }
Cache object: c5b218b5951660ab0aa0d79a125beb70
|