2 * Copyright (C) 2001 Julian Elischer <julian@freebsd.org>.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
29 #include "opt_witness.h"
30 #include "opt_hwpmc_hooks.h"
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/kernel.h>
39 #include <sys/mutex.h>
41 #include <sys/rangelock.h>
42 #include <sys/resourcevar.h>
45 #include <sys/sched.h>
46 #include <sys/sleepqueue.h>
47 #include <sys/selinfo.h>
48 #include <sys/syscallsubr.h>
49 #include <sys/sysent.h>
50 #include <sys/turnstile.h>
52 #include <sys/rwlock.h>
54 #include <sys/cpuset.h>
56 #include <sys/pmckern.h>
59 #include <security/audit/audit.h>
62 #include <vm/vm_extern.h>
64 #include <vm/vm_domain.h>
65 #include <sys/eventhandler.h>
67 SDT_PROVIDER_DECLARE(proc);
68 SDT_PROBE_DEFINE(proc, , , lwp__exit);
71 * thread related storage.
73 static uma_zone_t thread_zone;
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);
79 static void thread_zombie(struct thread *);
80 static int thread_unsuspend_one(struct thread *td, struct proc *p,
83 #define TID_BUFFER_SIZE 1024
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");
91 struct tidhashhead *tidhashtbl;
93 struct rwlock tidhash_lock;
100 tid = alloc_unr(tid_unrhdr);
104 if (tid_head == tid_tail) {
105 mtx_unlock(&tid_lock);
108 tid = tid_buffer[tid_head];
109 tid_head = (tid_head + 1) % TID_BUFFER_SIZE;
110 mtx_unlock(&tid_lock);
115 tid_free(lwpid_t tid)
117 lwpid_t tmp_tid = -1;
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;
124 tid_buffer[tid_tail] = tid;
125 tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE;
126 mtx_unlock(&tid_lock);
128 free_unr(tid_unrhdr, tmp_tid);
132 * Prepare a thread for use.
135 thread_ctor(void *mem, int size, void *arg, int flags)
139 td = (struct thread *)mem;
140 td->td_state = TDS_INACTIVE;
141 td->td_oncpu = NOCPU;
143 td->td_tid = tid_alloc();
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.
151 td->td_lend_user_pri = PRI_MAX;
152 EVENTHANDLER_INVOKE(thread_ctor, td);
154 audit_thread_alloc(td);
156 umtx_thread_alloc(td);
161 * Reclaim a thread after use.
164 thread_dtor(void *mem, int size, void *arg)
168 td = (struct thread *)mem;
171 /* Verify that this thread is in a safe state to free. */
172 switch (td->td_state) {
178 * We must never unlink a thread that is in one of
179 * these states, because it is currently active.
181 panic("bad state for thread unlinking");
186 panic("bad thread state");
191 audit_thread_free(td);
193 /* Free all OSD associated to this thread. */
196 EVENTHANDLER_INVOKE(thread_dtor, td);
197 tid_free(td->td_tid);
201 * Initialize type-stable parts of a thread (when newly created).
204 thread_init(void *mem, int size, int flags)
208 td = (struct thread *)mem;
210 td->td_sleepqueue = sleepq_alloc();
211 td->td_turnstile = turnstile_alloc();
213 EVENTHANDLER_INVOKE(thread_init, td);
214 td->td_sched = (struct td_sched *)&td[1];
215 umtx_thread_init(td);
222 * Tear down type-stable parts of a thread (just before being discarded).
225 thread_fini(void *mem, int size)
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);
239 * For a newly created process,
240 * link up all the structures and its initial threads etc.
242 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc.
243 * proc_dtor() (should go away)
247 proc_linkup0(struct proc *p, struct thread *td)
249 TAILQ_INIT(&p->p_threads); /* all threads in proc */
254 proc_linkup(struct proc *p, struct thread *td)
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;
263 LIST_INIT(&p->p_mqnotifier);
269 * Initialize global thread allocation resources.
275 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
278 * pid_max cannot be greater than PID_MAX.
279 * leave one number for thread0.
281 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock);
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");
291 * Place an unused thread on the zombie list.
292 * Use the slpq as that must be unused by now.
295 thread_zombie(struct thread *td)
297 mtx_lock_spin(&zombie_lock);
298 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq);
299 mtx_unlock_spin(&zombie_lock);
303 * Release a thread that has exited after cpu_throw().
306 thread_stash(struct thread *td)
308 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1);
313 * Reap zombie resources.
318 struct thread *td_first, *td_next;
321 * Don't even bother to lock if none at this instant,
322 * we really don't care about the next instant..
324 if (!TAILQ_EMPTY(&zombie_threads)) {
325 mtx_lock_spin(&zombie_lock);
326 td_first = TAILQ_FIRST(&zombie_threads);
328 TAILQ_INIT(&zombie_threads);
329 mtx_unlock_spin(&zombie_lock);
331 td_next = TAILQ_NEXT(td_first, td_slpq);
332 thread_cow_free(td_first);
333 thread_free(td_first);
343 thread_alloc(int pages)
347 thread_reap(); /* check if any zombies to get */
349 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK);
350 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
351 if (!vm_thread_new(td, pages)) {
352 uma_zfree(thread_zone, td);
355 cpu_thread_alloc(td);
356 vm_domain_policy_init(&td->td_vm_dom_policy);
361 thread_alloc_stack(struct thread *td, int pages)
364 KASSERT(td->td_kstack == 0,
365 ("thread_alloc_stack called on a thread with kstack"));
366 if (!vm_thread_new(td, pages))
368 cpu_thread_alloc(td);
373 * Deallocate a thread.
376 thread_free(struct thread *td)
379 lock_profile_thread_exit(td);
381 cpuset_rel(td->td_cpuset);
382 td->td_cpuset = NULL;
384 if (td->td_kstack != 0)
385 vm_thread_dispose(td);
386 vm_domain_policy_cleanup(&td->td_vm_dom_policy);
387 uma_zfree(thread_zone, td);
391 thread_cow_get_proc(struct thread *newtd, struct proc *p)
394 PROC_LOCK_ASSERT(p, MA_OWNED);
395 newtd->td_ucred = crhold(p->p_ucred);
396 newtd->td_limit = lim_hold(p->p_limit);
397 newtd->td_cowgen = p->p_cowgen;
401 thread_cow_get(struct thread *newtd, struct thread *td)
404 newtd->td_ucred = crhold(td->td_ucred);
405 newtd->td_limit = lim_hold(td->td_limit);
406 newtd->td_cowgen = td->td_cowgen;
410 thread_cow_free(struct thread *td)
413 if (td->td_ucred != NULL)
414 crfree(td->td_ucred);
415 if (td->td_limit != NULL)
416 lim_free(td->td_limit);
420 thread_cow_update(struct thread *td)
423 struct ucred *oldcred;
424 struct plimit *oldlimit;
430 if (td->td_ucred != p->p_ucred) {
431 oldcred = td->td_ucred;
432 td->td_ucred = crhold(p->p_ucred);
434 if (td->td_limit != p->p_limit) {
435 oldlimit = td->td_limit;
436 td->td_limit = lim_hold(p->p_limit);
438 td->td_cowgen = p->p_cowgen;
442 if (oldlimit != NULL)
447 * Discard the current thread and exit from its context.
448 * Always called with scheduler locked.
450 * Because we can't free a thread while we're operating under its context,
451 * push the current thread into our CPU's deadthread holder. This means
452 * we needn't worry about someone else grabbing our context before we
458 uint64_t runtime, new_switchtime;
467 PROC_SLOCK_ASSERT(p, MA_OWNED);
468 mtx_assert(&Giant, MA_NOTOWNED);
470 PROC_LOCK_ASSERT(p, MA_OWNED);
471 KASSERT(p != NULL, ("thread exiting without a process"));
472 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
473 (long)p->p_pid, td->td_name);
474 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
477 AUDIT_SYSCALL_EXIT(0, td);
480 * drop FPU & debug register state storage, or any other
481 * architecture specific resources that
482 * would not be on a new untouched process.
484 cpu_thread_exit(td); /* XXXSMP */
487 * The last thread is left attached to the process
488 * So that the whole bundle gets recycled. Skip
489 * all this stuff if we never had threads.
490 * EXIT clears all sign of other threads when
491 * it goes to single threading, so the last thread always
492 * takes the short path.
494 if (p->p_flag & P_HADTHREADS) {
495 if (p->p_numthreads > 1) {
496 atomic_add_int(&td->td_proc->p_exitthreads, 1);
498 td2 = FIRST_THREAD_IN_PROC(p);
499 sched_exit_thread(td2, td);
502 * The test below is NOT true if we are the
503 * sole exiting thread. P_STOPPED_SINGLE is unset
504 * in exit1() after it is the only survivor.
506 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
507 if (p->p_numthreads == p->p_suspcount) {
508 thread_lock(p->p_singlethread);
509 wakeup_swapper = thread_unsuspend_one(
510 p->p_singlethread, p, false);
511 thread_unlock(p->p_singlethread);
517 PCPU_SET(deadthread, td);
520 * The last thread is exiting.. but not through exit()
522 panic ("thread_exit: Last thread exiting on its own");
527 * If this thread is part of a process that is being tracked by hwpmc(4),
528 * inform the module of the thread's impending exit.
530 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
531 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
538 /* Do the same timestamp bookkeeping that mi_switch() would do. */
539 new_switchtime = cpu_ticks();
540 runtime = new_switchtime - PCPU_GET(switchtime);
541 td->td_runtime += runtime;
542 td->td_incruntime += runtime;
543 PCPU_SET(switchtime, new_switchtime);
544 PCPU_SET(switchticks, ticks);
545 PCPU_INC(cnt.v_swtch);
547 /* Save our resource usage in our process. */
548 td->td_ru.ru_nvcsw++;
550 rucollect(&p->p_ru, &td->td_ru);
553 td->td_state = TDS_INACTIVE;
555 witness_thread_exit(td);
557 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
559 panic("I'm a teapot!");
564 * Do any thread specific cleanups that may be needed in wait()
565 * called with Giant, proc and schedlock not held.
568 thread_wait(struct proc *p)
572 mtx_assert(&Giant, MA_NOTOWNED);
573 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()"));
574 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking"));
575 td = FIRST_THREAD_IN_PROC(p);
576 /* Lock the last thread so we spin until it exits cpu_throw(). */
579 lock_profile_thread_exit(td);
580 cpuset_rel(td->td_cpuset);
581 td->td_cpuset = NULL;
582 cpu_thread_clean(td);
584 thread_reap(); /* check for zombie threads etc. */
588 * Link a thread to a process.
589 * set up anything that needs to be initialized for it to
590 * be used by the process.
593 thread_link(struct thread *td, struct proc *p)
597 * XXX This can't be enabled because it's called for proc0 before
598 * its lock has been created.
599 * PROC_LOCK_ASSERT(p, MA_OWNED);
601 td->td_state = TDS_INACTIVE;
603 td->td_flags = TDF_INMEM;
605 LIST_INIT(&td->td_contested);
606 LIST_INIT(&td->td_lprof[0]);
607 LIST_INIT(&td->td_lprof[1]);
608 sigqueue_init(&td->td_sigqueue, p);
609 callout_init(&td->td_slpcallout, 1);
610 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist);
619 thread_unlink(struct thread *td)
621 struct proc *p = td->td_proc;
623 PROC_LOCK_ASSERT(p, MA_OWNED);
624 TAILQ_REMOVE(&p->p_threads, td, td_plist);
626 /* could clear a few other things here */
627 /* Must NOT clear links to proc! */
631 calc_remaining(struct proc *p, int mode)
635 PROC_LOCK_ASSERT(p, MA_OWNED);
636 PROC_SLOCK_ASSERT(p, MA_OWNED);
637 if (mode == SINGLE_EXIT)
638 remaining = p->p_numthreads;
639 else if (mode == SINGLE_BOUNDARY)
640 remaining = p->p_numthreads - p->p_boundary_count;
641 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC)
642 remaining = p->p_numthreads - p->p_suspcount;
644 panic("calc_remaining: wrong mode %d", mode);
649 remain_for_mode(int mode)
652 return (mode == SINGLE_ALLPROC ? 0 : 1);
656 weed_inhib(int mode, struct thread *td2, struct proc *p)
660 PROC_LOCK_ASSERT(p, MA_OWNED);
661 PROC_SLOCK_ASSERT(p, MA_OWNED);
662 THREAD_LOCK_ASSERT(td2, MA_OWNED);
667 if (TD_IS_SUSPENDED(td2))
668 wakeup_swapper |= thread_unsuspend_one(td2, p, true);
669 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0)
670 wakeup_swapper |= sleepq_abort(td2, EINTR);
672 case SINGLE_BOUNDARY:
673 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0)
674 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
675 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0)
676 wakeup_swapper |= sleepq_abort(td2, ERESTART);
679 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0)
680 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
681 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0)
682 wakeup_swapper |= sleepq_abort(td2, ERESTART);
686 * ALLPROC suspend tries to avoid spurious EINTR for
687 * threads sleeping interruptable, by suspending the
688 * thread directly, similarly to sig_suspend_threads().
689 * Since such sleep is not performed at the user
690 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP
691 * is used to avoid immediate un-suspend.
693 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY |
694 TDF_ALLPROCSUSP)) == 0)
695 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
696 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) {
697 if ((td2->td_flags & TDF_SBDRY) == 0) {
698 thread_suspend_one(td2);
699 td2->td_flags |= TDF_ALLPROCSUSP;
701 wakeup_swapper |= sleepq_abort(td2, ERESTART);
706 return (wakeup_swapper);
710 * Enforce single-threading.
712 * Returns 1 if the caller must abort (another thread is waiting to
713 * exit the process or similar). Process is locked!
714 * Returns 0 when you are successfully the only thread running.
715 * A process has successfully single threaded in the suspend mode when
716 * There are no threads in user mode. Threads in the kernel must be
717 * allowed to continue until they get to the user boundary. They may even
718 * copy out their return values and data before suspending. They may however be
719 * accelerated in reaching the user boundary as we will wake up
720 * any sleeping threads that are interruptable. (PCATCH).
723 thread_single(struct proc *p, int mode)
727 int remaining, wakeup_swapper;
730 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
731 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
732 ("invalid mode %d", mode));
734 * If allowing non-ALLPROC singlethreading for non-curproc
735 * callers, calc_remaining() and remain_for_mode() should be
736 * adjusted to also account for td->td_proc != p. For now
737 * this is not implemented because it is not used.
739 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) ||
740 (mode != SINGLE_ALLPROC && td->td_proc == p),
741 ("mode %d proc %p curproc %p", mode, p, td->td_proc));
742 mtx_assert(&Giant, MA_NOTOWNED);
743 PROC_LOCK_ASSERT(p, MA_OWNED);
745 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC)
748 /* Is someone already single threading? */
749 if (p->p_singlethread != NULL && p->p_singlethread != td)
752 if (mode == SINGLE_EXIT) {
753 p->p_flag |= P_SINGLE_EXIT;
754 p->p_flag &= ~P_SINGLE_BOUNDARY;
756 p->p_flag &= ~P_SINGLE_EXIT;
757 if (mode == SINGLE_BOUNDARY)
758 p->p_flag |= P_SINGLE_BOUNDARY;
760 p->p_flag &= ~P_SINGLE_BOUNDARY;
762 if (mode == SINGLE_ALLPROC)
763 p->p_flag |= P_TOTAL_STOP;
764 p->p_flag |= P_STOPPED_SINGLE;
766 p->p_singlethread = td;
767 remaining = calc_remaining(p, mode);
768 while (remaining != remain_for_mode(mode)) {
769 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE)
772 FOREACH_THREAD_IN_PROC(p, td2) {
776 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK;
777 if (TD_IS_INHIBITED(td2)) {
778 wakeup_swapper |= weed_inhib(mode, td2, p);
780 } else if (TD_IS_RUNNING(td2) && td != td2) {
788 remaining = calc_remaining(p, mode);
791 * Maybe we suspended some threads.. was it enough?
793 if (remaining == remain_for_mode(mode))
798 * Wake us up when everyone else has suspended.
799 * In the mean time we suspend as well.
801 thread_suspend_switch(td, p);
802 remaining = calc_remaining(p, mode);
804 if (mode == SINGLE_EXIT) {
806 * Convert the process to an unthreaded process. The
807 * SINGLE_EXIT is called by exit1() or execve(), in
808 * both cases other threads must be retired.
810 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads"));
811 p->p_singlethread = NULL;
812 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS);
815 * Wait for any remaining threads to exit cpu_throw().
817 while (p->p_exitthreads != 0) {
820 sched_relinquish(td);
824 } else if (mode == SINGLE_BOUNDARY) {
826 * Wait until all suspended threads are removed from
827 * the processors. The thread_suspend_check()
828 * increments p_boundary_count while it is still
829 * running, which makes it possible for the execve()
830 * to destroy vmspace while our other threads are
831 * still using the address space.
833 * We lock the thread, which is only allowed to
834 * succeed after context switch code finished using
837 FOREACH_THREAD_IN_PROC(p, td2) {
841 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0,
842 ("td %p not on boundary", td2));
843 KASSERT(TD_IS_SUSPENDED(td2),
844 ("td %p is not suspended", td2));
853 thread_suspend_check_needed(void)
860 PROC_LOCK_ASSERT(p, MA_OWNED);
861 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 &&
862 (td->td_dbgflags & TDB_SUSPEND) != 0));
866 * Called in from locations that can safely check to see
867 * whether we have to suspend or at least throttle for a
868 * single-thread event (e.g. fork).
870 * Such locations include userret().
871 * If the "return_instead" argument is non zero, the thread must be able to
872 * accept 0 (caller may continue), or 1 (caller must abort) as a result.
874 * The 'return_instead' argument tells the function if it may do a
875 * thread_exit() or suspend, or whether the caller must abort and back
878 * If the thread that set the single_threading request has set the
879 * P_SINGLE_EXIT bit in the process flags then this call will never return
880 * if 'return_instead' is false, but will exit.
882 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0
883 *---------------+--------------------+---------------------
884 * 0 | returns 0 | returns 0 or 1
885 * | when ST ends | immediately
886 *---------------+--------------------+---------------------
887 * 1 | thread exits | returns 1
889 * 0 = thread_exit() or suspension ok,
890 * other = return error instead of stopping the thread.
892 * While a full suspension is under effect, even a single threading
893 * thread would be suspended if it made this call (but it shouldn't).
894 * This call should only be made from places where
895 * thread_exit() would be safe as that may be the outcome unless
896 * return_instead is set.
899 thread_suspend_check(int return_instead)
907 mtx_assert(&Giant, MA_NOTOWNED);
908 PROC_LOCK_ASSERT(p, MA_OWNED);
909 while (thread_suspend_check_needed()) {
910 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
911 KASSERT(p->p_singlethread != NULL,
912 ("singlethread not set"));
914 * The only suspension in action is a
915 * single-threading. Single threader need not stop.
916 * XXX Should be safe to access unlocked
917 * as it can only be set to be true by us.
919 if (p->p_singlethread == td)
920 return (0); /* Exempt from stopping. */
922 if ((p->p_flag & P_SINGLE_EXIT) && return_instead)
925 /* Should we goto user boundary if we didn't come from there? */
926 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
927 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
931 * Ignore suspend requests if they are deferred.
933 if ((td->td_flags & TDF_SBDRY) != 0) {
934 KASSERT(return_instead,
935 ("TDF_SBDRY set for unsafe thread_suspend_check"));
940 * If the process is waiting for us to exit,
941 * this thread should just suicide.
942 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
944 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
948 * Allow Linux emulation layer to do some work
949 * before thread suicide.
951 if (__predict_false(p->p_sysent->sv_thread_detach != NULL))
952 (p->p_sysent->sv_thread_detach)(td);
953 umtx_thread_exit(td);
955 panic("stopped thread did not exit");
960 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
961 if (p->p_numthreads == p->p_suspcount + 1) {
962 thread_lock(p->p_singlethread);
963 wakeup_swapper = thread_unsuspend_one(
964 p->p_singlethread, p, false);
965 thread_unlock(p->p_singlethread);
973 * When a thread suspends, it just
974 * gets taken off all queues.
976 thread_suspend_one(td);
977 if (return_instead == 0) {
978 p->p_boundary_count++;
979 td->td_flags |= TDF_BOUNDARY;
982 mi_switch(SW_INVOL | SWT_SUSPEND, NULL);
990 thread_suspend_switch(struct thread *td, struct proc *p)
993 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
994 PROC_LOCK_ASSERT(p, MA_OWNED);
995 PROC_SLOCK_ASSERT(p, MA_OWNED);
997 * We implement thread_suspend_one in stages here to avoid
998 * dropping the proc lock while the thread lock is owned.
1000 if (p == td->td_proc) {
1006 td->td_flags &= ~TDF_NEEDSUSPCHK;
1007 TD_SET_SUSPENDED(td);
1011 mi_switch(SW_VOL | SWT_SUSPEND, NULL);
1019 thread_suspend_one(struct thread *td)
1024 PROC_SLOCK_ASSERT(p, MA_OWNED);
1025 THREAD_LOCK_ASSERT(td, MA_OWNED);
1026 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
1028 td->td_flags &= ~TDF_NEEDSUSPCHK;
1029 TD_SET_SUSPENDED(td);
1034 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary)
1037 THREAD_LOCK_ASSERT(td, MA_OWNED);
1038 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
1039 TD_CLR_SUSPENDED(td);
1040 td->td_flags &= ~TDF_ALLPROCSUSP;
1041 if (td->td_proc == p) {
1042 PROC_SLOCK_ASSERT(p, MA_OWNED);
1044 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) {
1045 td->td_flags &= ~TDF_BOUNDARY;
1046 p->p_boundary_count--;
1049 return (setrunnable(td));
1053 * Allow all threads blocked by single threading to continue running.
1056 thread_unsuspend(struct proc *p)
1061 PROC_LOCK_ASSERT(p, MA_OWNED);
1062 PROC_SLOCK_ASSERT(p, MA_OWNED);
1064 if (!P_SHOULDSTOP(p)) {
1065 FOREACH_THREAD_IN_PROC(p, td) {
1067 if (TD_IS_SUSPENDED(td)) {
1068 wakeup_swapper |= thread_unsuspend_one(td, p,
1073 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
1074 p->p_numthreads == p->p_suspcount) {
1076 * Stopping everything also did the job for the single
1077 * threading request. Now we've downgraded to single-threaded,
1080 if (p->p_singlethread->td_proc == p) {
1081 thread_lock(p->p_singlethread);
1082 wakeup_swapper = thread_unsuspend_one(
1083 p->p_singlethread, p, false);
1084 thread_unlock(p->p_singlethread);
1092 * End the single threading mode..
1095 thread_single_end(struct proc *p, int mode)
1100 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
1101 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
1102 ("invalid mode %d", mode));
1103 PROC_LOCK_ASSERT(p, MA_OWNED);
1104 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) ||
1105 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0),
1106 ("mode %d does not match P_TOTAL_STOP", mode));
1107 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread,
1108 ("thread_single_end from other thread %p %p",
1109 curthread, p->p_singlethread));
1110 KASSERT(mode != SINGLE_BOUNDARY ||
1111 (p->p_flag & P_SINGLE_BOUNDARY) != 0,
1112 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag));
1113 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY |
1116 p->p_singlethread = NULL;
1119 * If there are other threads they may now run,
1120 * unless of course there is a blanket 'stop order'
1121 * on the process. The single threader must be allowed
1122 * to continue however as this is a bad place to stop.
1124 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) {
1125 FOREACH_THREAD_IN_PROC(p, td) {
1127 if (TD_IS_SUSPENDED(td)) {
1128 wakeup_swapper |= thread_unsuspend_one(td, p,
1129 mode == SINGLE_BOUNDARY);
1134 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0,
1135 ("inconsistent boundary count %d", p->p_boundary_count));
1142 thread_find(struct proc *p, lwpid_t tid)
1146 PROC_LOCK_ASSERT(p, MA_OWNED);
1147 FOREACH_THREAD_IN_PROC(p, td) {
1148 if (td->td_tid == tid)
1154 /* Locate a thread by number; return with proc lock held. */
1156 tdfind(lwpid_t tid, pid_t pid)
1158 #define RUN_THRESH 16
1162 rw_rlock(&tidhash_lock);
1163 LIST_FOREACH(td, TIDHASH(tid), td_hash) {
1164 if (td->td_tid == tid) {
1165 if (pid != -1 && td->td_proc->p_pid != pid) {
1169 PROC_LOCK(td->td_proc);
1170 if (td->td_proc->p_state == PRS_NEW) {
1171 PROC_UNLOCK(td->td_proc);
1175 if (run > RUN_THRESH) {
1176 if (rw_try_upgrade(&tidhash_lock)) {
1177 LIST_REMOVE(td, td_hash);
1178 LIST_INSERT_HEAD(TIDHASH(td->td_tid),
1180 rw_wunlock(&tidhash_lock);
1188 rw_runlock(&tidhash_lock);
1193 tidhash_add(struct thread *td)
1195 rw_wlock(&tidhash_lock);
1196 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
1197 rw_wunlock(&tidhash_lock);
1201 tidhash_remove(struct thread *td)
1203 rw_wlock(&tidhash_lock);
1204 LIST_REMOVE(td, td_hash);
1205 rw_wunlock(&tidhash_lock);