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 <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/kernel.h>
36 #include <sys/mutex.h>
38 #include <sys/resourcevar.h>
40 #include <sys/sysctl.h>
41 #include <sys/sched.h>
42 #include <sys/sleepqueue.h>
43 #include <sys/turnstile.h>
47 #include <security/audit/audit.h>
50 #include <vm/vm_extern.h>
54 * KSEGRP related storage.
56 static uma_zone_t ksegrp_zone;
57 static uma_zone_t thread_zone;
60 SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0, "thread allocation");
61 static int thread_debug = 0;
62 SYSCTL_INT(_kern_threads, OID_AUTO, debug, CTLFLAG_RW,
63 &thread_debug, 0, "thread debug");
65 int max_threads_per_proc = 1500;
66 SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_per_proc, CTLFLAG_RW,
67 &max_threads_per_proc, 0, "Limit on threads per proc");
69 int max_groups_per_proc = 1500;
70 SYSCTL_INT(_kern_threads, OID_AUTO, max_groups_per_proc, CTLFLAG_RW,
71 &max_groups_per_proc, 0, "Limit on thread groups per proc");
74 SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_hits, CTLFLAG_RD,
75 &max_threads_hits, 0, "");
79 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads);
80 TAILQ_HEAD(, ksegrp) zombie_ksegrps = TAILQ_HEAD_INITIALIZER(zombie_ksegrps);
81 struct mtx kse_zombie_lock;
82 MTX_SYSINIT(kse_zombie_lock, &kse_zombie_lock, "kse zombie lock", MTX_SPIN);
85 sysctl_kse_virtual_cpu(SYSCTL_HANDLER_ARGS)
94 new_val = virtual_cpu;
95 error = sysctl_handle_int(oidp, &new_val, 0, req);
96 if (error != 0 || req->newptr == NULL)
100 virtual_cpu = new_val;
105 SYSCTL_PROC(_kern_threads, OID_AUTO, virtual_cpu, CTLTYPE_INT|CTLFLAG_RW,
106 0, sizeof(virtual_cpu), sysctl_kse_virtual_cpu, "I",
107 "debug virtual cpus");
110 static struct unrhdr *tid_unrhdr;
113 * Prepare a thread for use.
116 thread_ctor(void *mem, int size, void *arg, int flags)
120 td = (struct thread *)mem;
121 td->td_state = TDS_INACTIVE;
122 td->td_oncpu = NOCPU;
124 td->td_tid = alloc_unr(tid_unrhdr);
127 * Note that td_critnest begins life as 1 because the thread is not
128 * running and is thereby implicitly waiting to be on the receiving
129 * end of a context switch. A context switch must occur inside a
130 * critical section, and in fact, includes hand-off of the sched_lock.
131 * After a context switch to a newly created thread, it will release
132 * sched_lock for the first time, and its td_critnest will hit 0 for
133 * the first time. This happens on the far end of a context switch,
134 * and when it context switches away from itself, it will in fact go
135 * back into a critical section, and hand off the sched lock to the
141 audit_thread_alloc(td);
143 umtx_thread_alloc(td);
148 * Reclaim a thread after use.
151 thread_dtor(void *mem, int size, void *arg)
155 td = (struct thread *)mem;
158 /* Verify that this thread is in a safe state to free. */
159 switch (td->td_state) {
165 * We must never unlink a thread that is in one of
166 * these states, because it is currently active.
168 panic("bad state for thread unlinking");
173 panic("bad thread state");
178 audit_thread_free(td);
180 free_unr(tid_unrhdr, td->td_tid);
185 * Initialize type-stable parts of a thread (when newly created).
188 thread_init(void *mem, int size, int flags)
192 td = (struct thread *)mem;
194 vm_thread_new(td, 0);
195 cpu_thread_setup(td);
196 td->td_sleepqueue = sleepq_alloc();
197 td->td_turnstile = turnstile_alloc();
198 td->td_sched = (struct td_sched *)&td[1];
200 umtx_thread_init(td);
205 * Tear down type-stable parts of a thread (just before being discarded).
208 thread_fini(void *mem, int size)
212 td = (struct thread *)mem;
213 turnstile_free(td->td_turnstile);
214 sleepq_free(td->td_sleepqueue);
215 umtx_thread_fini(td);
216 vm_thread_dispose(td);
220 * Initialize type-stable parts of a ksegrp (when newly created).
223 ksegrp_ctor(void *mem, int size, void *arg, int flags)
227 kg = (struct ksegrp *)mem;
229 kg->kg_sched = (struct kg_sched *)&kg[1];
234 ksegrp_link(struct ksegrp *kg, struct proc *p)
237 TAILQ_INIT(&kg->kg_threads);
238 TAILQ_INIT(&kg->kg_runq); /* links with td_runq */
239 TAILQ_INIT(&kg->kg_upcalls); /* all upcall structure in ksegrp */
242 * the following counters are in the -zero- section
243 * and may not need clearing
245 kg->kg_numthreads = 0;
246 kg->kg_numupcalls = 0;
247 /* link it in now that it's consistent */
249 TAILQ_INSERT_HEAD(&p->p_ksegrps, kg, kg_ksegrp);
257 ksegrp_unlink(struct ksegrp *kg)
261 mtx_assert(&sched_lock, MA_OWNED);
262 KASSERT((kg->kg_numthreads == 0), ("ksegrp_unlink: residual threads"));
263 KASSERT((kg->kg_numupcalls == 0), ("ksegrp_unlink: residual upcalls"));
266 TAILQ_REMOVE(&p->p_ksegrps, kg, kg_ksegrp);
269 * Aggregate stats from the KSE
271 if (p->p_procscopegrp == kg)
272 p->p_procscopegrp = NULL;
276 * For a newly created process,
277 * link up all the structures and its initial threads etc.
279 * {arch}/{arch}/machdep.c ia64_init(), init386() etc.
280 * proc_dtor() (should go away)
284 proc_linkup(struct proc *p, struct ksegrp *kg, struct thread *td)
287 TAILQ_INIT(&p->p_ksegrps); /* all ksegrps in proc */
288 TAILQ_INIT(&p->p_threads); /* all threads in proc */
289 TAILQ_INIT(&p->p_suspended); /* Threads suspended */
290 sigqueue_init(&p->p_sigqueue, p);
291 p->p_ksi = ksiginfo_alloc(1);
292 if (p->p_ksi != NULL) {
293 /* XXX p_ksi may be null if ksiginfo zone is not ready */
294 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS;
296 LIST_INIT(&p->p_mqnotifier);
305 * Initialize global thread allocation resources.
311 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
312 tid_unrhdr = new_unrhdr(PID_MAX + 1, INT_MAX, &tid_lock);
314 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
315 thread_ctor, thread_dtor, thread_init, thread_fini,
317 ksegrp_zone = uma_zcreate("KSEGRP", sched_sizeof_ksegrp(),
318 ksegrp_ctor, NULL, NULL, NULL,
320 kseinit(); /* set up kse specific stuff e.g. upcall zone*/
324 * Stash an embarasingly extra thread into the zombie thread queue.
327 thread_stash(struct thread *td)
329 mtx_lock_spin(&kse_zombie_lock);
330 TAILQ_INSERT_HEAD(&zombie_threads, td, td_runq);
331 mtx_unlock_spin(&kse_zombie_lock);
335 * Stash an embarasingly extra ksegrp into the zombie ksegrp queue.
338 ksegrp_stash(struct ksegrp *kg)
340 mtx_lock_spin(&kse_zombie_lock);
341 TAILQ_INSERT_HEAD(&zombie_ksegrps, kg, kg_ksegrp);
342 mtx_unlock_spin(&kse_zombie_lock);
346 * Reap zombie kse resource.
351 struct thread *td_first, *td_next;
352 struct ksegrp *kg_first, * kg_next;
355 * Don't even bother to lock if none at this instant,
356 * we really don't care about the next instant..
358 if ((!TAILQ_EMPTY(&zombie_threads))
359 || (!TAILQ_EMPTY(&zombie_ksegrps))) {
360 mtx_lock_spin(&kse_zombie_lock);
361 td_first = TAILQ_FIRST(&zombie_threads);
362 kg_first = TAILQ_FIRST(&zombie_ksegrps);
364 TAILQ_INIT(&zombie_threads);
366 TAILQ_INIT(&zombie_ksegrps);
367 mtx_unlock_spin(&kse_zombie_lock);
369 td_next = TAILQ_NEXT(td_first, td_runq);
370 if (td_first->td_ucred)
371 crfree(td_first->td_ucred);
372 thread_free(td_first);
376 kg_next = TAILQ_NEXT(kg_first, kg_ksegrp);
377 ksegrp_free(kg_first);
381 * there will always be a thread on the list if one of these
394 return (uma_zalloc(ksegrp_zone, M_WAITOK));
403 thread_reap(); /* check if any zombies to get */
404 return (uma_zalloc(thread_zone, M_WAITOK));
408 * Deallocate a ksegrp.
411 ksegrp_free(struct ksegrp *td)
413 uma_zfree(ksegrp_zone, td);
417 * Deallocate a thread.
420 thread_free(struct thread *td)
423 cpu_thread_clean(td);
424 uma_zfree(thread_zone, td);
428 * Discard the current thread and exit from its context.
429 * Always called with scheduler locked.
431 * Because we can't free a thread while we're operating under its context,
432 * push the current thread into our CPU's deadthread holder. This means
433 * we needn't worry about someone else grabbing our context before we
434 * do a cpu_throw(). This may not be needed now as we are under schedlock.
435 * Maybe we can just do a thread_stash() as thr_exit1 does.
438 * libthr expects its thread exit to return for the last
439 * thread, meaning that the program is back to non-threaded
440 * mode I guess. Because we do this (cpu_throw) unconditionally
441 * here, they have their own version of it. (thr_exit1())
442 * that doesn't do it all if this was the last thread.
443 * It is also called from thread_suspend_check().
444 * Of course in the end, they end up coming here through exit1
445 * anyhow.. After fixing 'thr' to play by the rules we should be able
446 * to merge these two functions together.
452 * thread_user_enter()
454 * thread_suspend_check()
459 uint64_t new_switchtime;
468 mtx_assert(&sched_lock, MA_OWNED);
469 mtx_assert(&Giant, MA_NOTOWNED);
470 PROC_LOCK_ASSERT(p, MA_OWNED);
471 KASSERT(p != NULL, ("thread exiting without a process"));
472 KASSERT(kg != NULL, ("thread exiting without a kse group"));
473 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
474 (long)p->p_pid, p->p_comm);
475 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
478 AUDIT_SYSCALL_EXIT(0, td);
481 if (td->td_standin != NULL) {
483 * Note that we don't need to free the cred here as it
484 * is done in thread_reap().
486 thread_stash(td->td_standin);
487 td->td_standin = NULL;
490 umtx_thread_exit(td);
493 * drop FPU & debug register state storage, or any other
494 * architecture specific resources that
495 * would not be on a new untouched process.
497 cpu_thread_exit(td); /* XXXSMP */
500 * The thread is exiting. scheduler can release its stuff
501 * and collect stats etc.
502 * XXX this is not very right, since PROC_UNLOCK may still
503 * need scheduler stuff.
505 sched_thread_exit(td);
507 /* Do the same timestamp bookkeeping that mi_switch() would do. */
508 new_switchtime = cpu_ticks();
509 p->p_rux.rux_runtime += (new_switchtime - PCPU_GET(switchtime));
510 p->p_rux.rux_uticks += td->td_uticks;
511 p->p_rux.rux_sticks += td->td_sticks;
512 p->p_rux.rux_iticks += td->td_iticks;
513 PCPU_SET(switchtime, new_switchtime);
514 PCPU_SET(switchticks, ticks);
517 /* Add our usage into the usage of all our children. */
518 if (p->p_numthreads == 1)
519 ruadd(p->p_ru, &p->p_rux, &p->p_stats->p_cru, &p->p_crux);
522 * The last thread is left attached to the process
523 * So that the whole bundle gets recycled. Skip
524 * all this stuff if we never had threads.
525 * EXIT clears all sign of other threads when
526 * it goes to single threading, so the last thread always
527 * takes the short path.
529 if (p->p_flag & P_HADTHREADS) {
530 if (p->p_numthreads > 1) {
533 /* XXX first arg not used in 4BSD or ULE */
534 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td);
537 * The test below is NOT true if we are the
538 * sole exiting thread. P_STOPPED_SNGL is unset
539 * in exit1() after it is the only survivor.
541 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
542 if (p->p_numthreads == p->p_suspcount) {
543 thread_unsuspend_one(p->p_singlethread);
548 * Because each upcall structure has an owner thread,
549 * owner thread exits only when process is in exiting
550 * state, so upcall to userland is no longer needed,
551 * deleting upcall structure is safe here.
552 * So when all threads in a group is exited, all upcalls
553 * in the group should be automatically freed.
554 * XXXKSE This is a KSE thing and should be exported
560 * If the thread we unlinked above was the last one,
561 * then this ksegrp should go away too.
563 if (kg->kg_numthreads == 0) {
565 * let the scheduler know about this in case
566 * it needs to recover stats or resources.
567 * Theoretically we could let
568 * sched_exit_ksegrp() do the equivalent of
569 * setting the concurrency to 0
570 * but don't do it yet to avoid changing
571 * the existing scheduler code until we
573 * We supply a random other ksegrp
574 * as the recipient of any built up
575 * cpu usage etc. (If the scheduler wants it).
577 * This is probably not fair so think of
580 sched_exit_ksegrp(FIRST_KSEGRP_IN_PROC(p), td);
581 sched_set_concurrency(kg, 0); /* XXX TEMP */
586 td->td_ksegrp = NULL;
587 PCPU_SET(deadthread, td);
590 * The last thread is exiting.. but not through exit()
592 * Theoretically this can't happen
593 * exit1() - clears threading flags before coming here
594 * kse_exit() - treats last thread specially
595 * thr_exit() - treats last thread specially
596 * thread_user_enter() - only if more exist
597 * thread_userret() - only if more exist
598 * thread_suspend_check() - only if more exist
600 panic ("thread_exit: Last thread exiting on its own");
604 * non threaded process comes here.
605 * This includes an EX threaded process that is coming
606 * here via exit1(). (exit1 dethreads the proc first).
610 td->td_state = TDS_INACTIVE;
611 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
612 cpu_throw(td, choosethread());
613 panic("I'm a teapot!");
618 * Do any thread specific cleanups that may be needed in wait()
619 * called with Giant, proc and schedlock not held.
622 thread_wait(struct proc *p)
626 mtx_assert(&Giant, MA_NOTOWNED);
627 KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()"));
628 KASSERT((p->p_numksegrps == 1), ("Multiple ksegrps in wait1()"));
629 FOREACH_THREAD_IN_PROC(p, td) {
630 if (td->td_standin != NULL) {
631 if (td->td_standin->td_ucred != NULL) {
632 crfree(td->td_standin->td_ucred);
633 td->td_standin->td_ucred = NULL;
635 thread_free(td->td_standin);
636 td->td_standin = NULL;
638 cpu_thread_clean(td);
639 crfree(td->td_ucred);
641 thread_reap(); /* check for zombie threads etc. */
645 * Link a thread to a process.
646 * set up anything that needs to be initialized for it to
647 * be used by the process.
649 * Note that we do not link to the proc's ucred here.
650 * The thread is linked as if running but no KSE assigned.
653 * thread_schedule_upcall()
657 thread_link(struct thread *td, struct ksegrp *kg)
662 td->td_state = TDS_INACTIVE;
668 LIST_INIT(&td->td_contested);
669 sigqueue_init(&td->td_sigqueue, p);
670 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE);
671 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist);
672 TAILQ_INSERT_HEAD(&kg->kg_threads, td, td_kglist);
678 * Convert a process with one thread to an unthreaded process.
680 * thread_single(exit) (called from execve and exit)
681 * kse_exit() XXX may need cleaning up wrt KSE stuff
684 thread_unthread(struct thread *td)
686 struct proc *p = td->td_proc;
688 KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads"));
690 p->p_flag &= ~(P_SA|P_HADTHREADS);
691 td->td_mailbox = NULL;
692 td->td_pflags &= ~(TDP_SA | TDP_CAN_UNBIND);
693 if (td->td_standin != NULL) {
694 thread_stash(td->td_standin);
695 td->td_standin = NULL;
697 sched_set_concurrency(td->td_ksegrp, 1);
705 thread_unlink(struct thread *td)
707 struct proc *p = td->td_proc;
708 struct ksegrp *kg = td->td_ksegrp;
710 mtx_assert(&sched_lock, MA_OWNED);
711 TAILQ_REMOVE(&p->p_threads, td, td_plist);
713 TAILQ_REMOVE(&kg->kg_threads, td, td_kglist);
715 /* could clear a few other things here */
716 /* Must NOT clear links to proc and ksegrp! */
720 * Enforce single-threading.
722 * Returns 1 if the caller must abort (another thread is waiting to
723 * exit the process or similar). Process is locked!
724 * Returns 0 when you are successfully the only thread running.
725 * A process has successfully single threaded in the suspend mode when
726 * There are no threads in user mode. Threads in the kernel must be
727 * allowed to continue until they get to the user boundary. They may even
728 * copy out their return values and data before suspending. They may however be
729 * accelerated in reaching the user boundary as we will wake up
730 * any sleeping threads that are interruptable. (PCATCH).
733 thread_single(int mode)
742 mtx_assert(&Giant, MA_NOTOWNED);
743 PROC_LOCK_ASSERT(p, MA_OWNED);
744 KASSERT((td != NULL), ("curthread is NULL"));
746 if ((p->p_flag & P_HADTHREADS) == 0)
749 /* Is someone already single threading? */
750 if (p->p_singlethread != NULL && p->p_singlethread != td)
753 if (mode == SINGLE_EXIT) {
754 p->p_flag |= P_SINGLE_EXIT;
755 p->p_flag &= ~P_SINGLE_BOUNDARY;
757 p->p_flag &= ~P_SINGLE_EXIT;
758 if (mode == SINGLE_BOUNDARY)
759 p->p_flag |= P_SINGLE_BOUNDARY;
761 p->p_flag &= ~P_SINGLE_BOUNDARY;
763 p->p_flag |= P_STOPPED_SINGLE;
764 mtx_lock_spin(&sched_lock);
765 p->p_singlethread = td;
766 if (mode == SINGLE_EXIT)
767 remaining = p->p_numthreads;
768 else if (mode == SINGLE_BOUNDARY)
769 remaining = p->p_numthreads - p->p_boundary_count;
771 remaining = p->p_numthreads - p->p_suspcount;
772 while (remaining != 1) {
773 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE)
775 FOREACH_THREAD_IN_PROC(p, td2) {
778 td2->td_flags |= TDF_ASTPENDING;
779 if (TD_IS_INHIBITED(td2)) {
782 if (td->td_flags & TDF_DBSUSPEND)
783 td->td_flags &= ~TDF_DBSUSPEND;
784 if (TD_IS_SUSPENDED(td2))
785 thread_unsuspend_one(td2);
786 if (TD_ON_SLEEPQ(td2) &&
787 (td2->td_flags & TDF_SINTR))
788 sleepq_abort(td2, EINTR);
790 case SINGLE_BOUNDARY:
791 if (TD_IS_SUSPENDED(td2) &&
792 !(td2->td_flags & TDF_BOUNDARY))
793 thread_unsuspend_one(td2);
794 if (TD_ON_SLEEPQ(td2) &&
795 (td2->td_flags & TDF_SINTR))
796 sleepq_abort(td2, ERESTART);
799 if (TD_IS_SUSPENDED(td2))
802 * maybe other inhibitted states too?
804 if ((td2->td_flags & TDF_SINTR) &&
805 (td2->td_inhibitors &
806 (TDI_SLEEPING | TDI_SWAPPED)))
807 thread_suspend_one(td2);
812 else if (TD_IS_RUNNING(td2) && td != td2) {
817 if (mode == SINGLE_EXIT)
818 remaining = p->p_numthreads;
819 else if (mode == SINGLE_BOUNDARY)
820 remaining = p->p_numthreads - p->p_boundary_count;
822 remaining = p->p_numthreads - p->p_suspcount;
825 * Maybe we suspended some threads.. was it enough?
832 * Wake us up when everyone else has suspended.
833 * In the mean time we suspend as well.
836 thread_suspend_one(td);
838 mi_switch(SW_VOL, NULL);
839 mtx_unlock_spin(&sched_lock);
841 mtx_lock_spin(&sched_lock);
842 if (mode == SINGLE_EXIT)
843 remaining = p->p_numthreads;
844 else if (mode == SINGLE_BOUNDARY)
845 remaining = p->p_numthreads - p->p_boundary_count;
847 remaining = p->p_numthreads - p->p_suspcount;
849 if (mode == SINGLE_EXIT) {
851 * We have gotten rid of all the other threads and we
852 * are about to either exit or exec. In either case,
853 * we try our utmost to revert to being a non-threaded
856 p->p_singlethread = NULL;
857 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT);
860 mtx_unlock_spin(&sched_lock);
865 * Called in from locations that can safely check to see
866 * whether we have to suspend or at least throttle for a
867 * single-thread event (e.g. fork).
869 * Such locations include userret().
870 * If the "return_instead" argument is non zero, the thread must be able to
871 * accept 0 (caller may continue), or 1 (caller must abort) as a result.
873 * The 'return_instead' argument tells the function if it may do a
874 * thread_exit() or suspend, or whether the caller must abort and back
877 * If the thread that set the single_threading request has set the
878 * P_SINGLE_EXIT bit in the process flags then this call will never return
879 * if 'return_instead' is false, but will exit.
881 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0
882 *---------------+--------------------+---------------------
883 * 0 | returns 0 | returns 0 or 1
884 * | when ST ends | immediatly
885 *---------------+--------------------+---------------------
886 * 1 | thread exits | returns 1
888 * 0 = thread_exit() or suspension ok,
889 * other = return error instead of stopping the thread.
891 * While a full suspension is under effect, even a single threading
892 * thread would be suspended if it made this call (but it shouldn't).
893 * This call should only be made from places where
894 * thread_exit() would be safe as that may be the outcome unless
895 * return_instead is set.
898 thread_suspend_check(int return_instead)
905 mtx_assert(&Giant, MA_NOTOWNED);
906 PROC_LOCK_ASSERT(p, MA_OWNED);
907 while (P_SHOULDSTOP(p) ||
908 ((p->p_flag & P_TRACED) && (td->td_flags & TDF_DBSUSPEND))) {
909 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
910 KASSERT(p->p_singlethread != NULL,
911 ("singlethread not set"));
913 * The only suspension in action is a
914 * single-threading. Single threader need not stop.
915 * XXX Should be safe to access unlocked
916 * as it can only be set to be true by us.
918 if (p->p_singlethread == td)
919 return (0); /* Exempt from stopping. */
921 if ((p->p_flag & P_SINGLE_EXIT) && return_instead)
924 /* Should we goto user boundary if we didn't come from there? */
925 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
926 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
929 /* If thread will exit, flush its pending signals */
930 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td))
931 sigqueue_flush(&td->td_sigqueue);
933 mtx_lock_spin(&sched_lock);
936 * If the process is waiting for us to exit,
937 * this thread should just suicide.
938 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
940 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td))
944 * When a thread suspends, it just
945 * moves to the processes's suspend queue
948 thread_suspend_one(td);
949 if (return_instead == 0) {
950 p->p_boundary_count++;
951 td->td_flags |= TDF_BOUNDARY;
953 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
954 if (p->p_numthreads == p->p_suspcount)
955 thread_unsuspend_one(p->p_singlethread);
958 mi_switch(SW_INVOL, NULL);
959 if (return_instead == 0) {
960 p->p_boundary_count--;
961 td->td_flags &= ~TDF_BOUNDARY;
963 mtx_unlock_spin(&sched_lock);
970 thread_suspend_one(struct thread *td)
972 struct proc *p = td->td_proc;
974 mtx_assert(&sched_lock, MA_OWNED);
975 PROC_LOCK_ASSERT(p, MA_OWNED);
976 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
978 TD_SET_SUSPENDED(td);
979 TAILQ_INSERT_TAIL(&p->p_suspended, td, td_runq);
983 thread_unsuspend_one(struct thread *td)
985 struct proc *p = td->td_proc;
987 mtx_assert(&sched_lock, MA_OWNED);
988 PROC_LOCK_ASSERT(p, MA_OWNED);
989 TAILQ_REMOVE(&p->p_suspended, td, td_runq);
990 TD_CLR_SUSPENDED(td);
996 * Allow all threads blocked by single threading to continue running.
999 thread_unsuspend(struct proc *p)
1003 mtx_assert(&sched_lock, MA_OWNED);
1004 PROC_LOCK_ASSERT(p, MA_OWNED);
1005 if (!P_SHOULDSTOP(p)) {
1006 while ((td = TAILQ_FIRST(&p->p_suspended))) {
1007 thread_unsuspend_one(td);
1009 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) &&
1010 (p->p_numthreads == p->p_suspcount)) {
1012 * Stopping everything also did the job for the single
1013 * threading request. Now we've downgraded to single-threaded,
1016 thread_unsuspend_one(p->p_singlethread);
1021 * End the single threading mode..
1024 thread_single_end(void)
1031 PROC_LOCK_ASSERT(p, MA_OWNED);
1032 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY);
1033 mtx_lock_spin(&sched_lock);
1034 p->p_singlethread = NULL;
1035 p->p_procscopegrp = NULL;
1037 * If there are other threads they mey now run,
1038 * unless of course there is a blanket 'stop order'
1039 * on the process. The single threader must be allowed
1040 * to continue however as this is a bad place to stop.
1042 if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) {
1043 while ((td = TAILQ_FIRST(&p->p_suspended))) {
1044 thread_unsuspend_one(td);
1047 mtx_unlock_spin(&sched_lock);
1051 thread_find(struct proc *p, lwpid_t tid)
1055 PROC_LOCK_ASSERT(p, MA_OWNED);
1056 mtx_lock_spin(&sched_lock);
1057 FOREACH_THREAD_IN_PROC(p, td) {
1058 if (td->td_tid == tid)
1061 mtx_unlock_spin(&sched_lock);