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/resourcevar.h>
43 #include <sys/sched.h>
44 #include <sys/sleepqueue.h>
45 #include <sys/selinfo.h>
46 #include <sys/turnstile.h>
48 #include <sys/rwlock.h>
50 #include <sys/cpuset.h>
52 #include <sys/pmckern.h>
55 #include <security/audit/audit.h>
58 #include <vm/vm_extern.h>
60 #include <sys/eventhandler.h>
63 * thread related storage.
65 static uma_zone_t thread_zone;
67 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads);
68 static struct mtx zombie_lock;
69 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN);
71 static void thread_zombie(struct thread *);
73 #define TID_BUFFER_SIZE 1024
76 static struct unrhdr *tid_unrhdr;
77 static lwpid_t tid_buffer[TID_BUFFER_SIZE];
78 static int tid_head, tid_tail;
79 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash");
81 struct tidhashhead *tidhashtbl;
83 struct rwlock tidhash_lock;
90 tid = alloc_unr(tid_unrhdr);
94 if (tid_head == tid_tail) {
95 mtx_unlock(&tid_lock);
98 tid = tid_buffer[tid_head++];
99 tid_head %= TID_BUFFER_SIZE;
100 mtx_unlock(&tid_lock);
105 tid_free(lwpid_t tid)
107 lwpid_t tmp_tid = -1;
110 if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) {
111 tmp_tid = tid_buffer[tid_head++];
112 tid_head = (tid_head + 1) % TID_BUFFER_SIZE;
114 tid_buffer[tid_tail++] = tid;
115 tid_tail %= TID_BUFFER_SIZE;
116 mtx_unlock(&tid_lock);
118 free_unr(tid_unrhdr, tmp_tid);
122 * Prepare a thread for use.
125 thread_ctor(void *mem, int size, void *arg, int flags)
129 td = (struct thread *)mem;
130 td->td_state = TDS_INACTIVE;
131 td->td_oncpu = NOCPU;
133 td->td_tid = tid_alloc();
136 * Note that td_critnest begins life as 1 because the thread is not
137 * running and is thereby implicitly waiting to be on the receiving
138 * end of a context switch.
141 td->td_lend_user_pri = PRI_MAX;
142 EVENTHANDLER_INVOKE(thread_ctor, td);
144 audit_thread_alloc(td);
146 umtx_thread_alloc(td);
151 * Reclaim a thread after use.
154 thread_dtor(void *mem, int size, void *arg)
158 td = (struct thread *)mem;
161 /* Verify that this thread is in a safe state to free. */
162 switch (td->td_state) {
168 * We must never unlink a thread that is in one of
169 * these states, because it is currently active.
171 panic("bad state for thread unlinking");
176 panic("bad thread state");
181 audit_thread_free(td);
183 /* Free all OSD associated to this thread. */
186 EVENTHANDLER_INVOKE(thread_dtor, td);
187 tid_free(td->td_tid);
191 * Initialize type-stable parts of a thread (when newly created).
194 thread_init(void *mem, int size, int flags)
198 td = (struct thread *)mem;
200 td->td_sleepqueue = sleepq_alloc();
201 td->td_turnstile = turnstile_alloc();
202 EVENTHANDLER_INVOKE(thread_init, td);
203 td->td_sched = (struct td_sched *)&td[1];
204 umtx_thread_init(td);
210 * Tear down type-stable parts of a thread (just before being discarded).
213 thread_fini(void *mem, int size)
217 td = (struct thread *)mem;
218 EVENTHANDLER_INVOKE(thread_fini, td);
219 turnstile_free(td->td_turnstile);
220 sleepq_free(td->td_sleepqueue);
221 umtx_thread_fini(td);
226 * For a newly created process,
227 * link up all the structures and its initial threads etc.
229 * {arch}/{arch}/machdep.c ia64_init(), init386() etc.
230 * proc_dtor() (should go away)
234 proc_linkup0(struct proc *p, struct thread *td)
236 TAILQ_INIT(&p->p_threads); /* all threads in proc */
241 proc_linkup(struct proc *p, struct thread *td)
244 sigqueue_init(&p->p_sigqueue, p);
245 p->p_ksi = ksiginfo_alloc(1);
246 if (p->p_ksi != NULL) {
247 /* XXX p_ksi may be null if ksiginfo zone is not ready */
248 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS;
250 LIST_INIT(&p->p_mqnotifier);
256 * Initialize global thread allocation resources.
262 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
263 /* leave one number for thread0 */
264 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock);
266 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
267 thread_ctor, thread_dtor, thread_init, thread_fini,
269 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash);
270 rw_init(&tidhash_lock, "tidhash");
274 * Place an unused thread on the zombie list.
275 * Use the slpq as that must be unused by now.
278 thread_zombie(struct thread *td)
280 mtx_lock_spin(&zombie_lock);
281 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq);
282 mtx_unlock_spin(&zombie_lock);
286 * Release a thread that has exited after cpu_throw().
289 thread_stash(struct thread *td)
291 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1);
296 * Reap zombie resources.
301 struct thread *td_first, *td_next;
304 * Don't even bother to lock if none at this instant,
305 * we really don't care about the next instant..
307 if (!TAILQ_EMPTY(&zombie_threads)) {
308 mtx_lock_spin(&zombie_lock);
309 td_first = TAILQ_FIRST(&zombie_threads);
311 TAILQ_INIT(&zombie_threads);
312 mtx_unlock_spin(&zombie_lock);
314 td_next = TAILQ_NEXT(td_first, td_slpq);
315 if (td_first->td_ucred)
316 crfree(td_first->td_ucred);
317 thread_free(td_first);
327 thread_alloc(int pages)
331 thread_reap(); /* check if any zombies to get */
333 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK);
334 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
335 if (!vm_thread_new(td, pages)) {
336 uma_zfree(thread_zone, td);
339 cpu_thread_alloc(td);
344 thread_alloc_stack(struct thread *td, int pages)
347 KASSERT(td->td_kstack == 0,
348 ("thread_alloc_stack called on a thread with kstack"));
349 if (!vm_thread_new(td, pages))
351 cpu_thread_alloc(td);
356 * Deallocate a thread.
359 thread_free(struct thread *td)
362 lock_profile_thread_exit(td);
364 cpuset_rel(td->td_cpuset);
365 td->td_cpuset = NULL;
367 if (td->td_kstack != 0)
368 vm_thread_dispose(td);
369 uma_zfree(thread_zone, td);
373 * Discard the current thread and exit from its context.
374 * Always called with scheduler locked.
376 * Because we can't free a thread while we're operating under its context,
377 * push the current thread into our CPU's deadthread holder. This means
378 * we needn't worry about someone else grabbing our context before we
384 uint64_t runtime, new_switchtime;
393 PROC_SLOCK_ASSERT(p, MA_OWNED);
394 mtx_assert(&Giant, MA_NOTOWNED);
396 PROC_LOCK_ASSERT(p, MA_OWNED);
397 KASSERT(p != NULL, ("thread exiting without a process"));
398 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
399 (long)p->p_pid, td->td_name);
400 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
403 AUDIT_SYSCALL_EXIT(0, td);
405 umtx_thread_exit(td);
407 * drop FPU & debug register state storage, or any other
408 * architecture specific resources that
409 * would not be on a new untouched process.
411 cpu_thread_exit(td); /* XXXSMP */
414 * The last thread is left attached to the process
415 * So that the whole bundle gets recycled. Skip
416 * all this stuff if we never had threads.
417 * EXIT clears all sign of other threads when
418 * it goes to single threading, so the last thread always
419 * takes the short path.
421 if (p->p_flag & P_HADTHREADS) {
422 if (p->p_numthreads > 1) {
424 td2 = FIRST_THREAD_IN_PROC(p);
425 sched_exit_thread(td2, td);
428 * The test below is NOT true if we are the
429 * sole exiting thread. P_STOPPED_SINGLE is unset
430 * in exit1() after it is the only survivor.
432 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
433 if (p->p_numthreads == p->p_suspcount) {
434 thread_lock(p->p_singlethread);
435 wakeup_swapper = thread_unsuspend_one(
437 thread_unlock(p->p_singlethread);
443 atomic_add_int(&td->td_proc->p_exitthreads, 1);
444 PCPU_SET(deadthread, td);
447 * The last thread is exiting.. but not through exit()
449 panic ("thread_exit: Last thread exiting on its own");
454 * If this thread is part of a process that is being tracked by hwpmc(4),
455 * inform the module of the thread's impending exit.
457 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
458 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
462 /* Do the same timestamp bookkeeping that mi_switch() would do. */
463 new_switchtime = cpu_ticks();
464 runtime = new_switchtime - PCPU_GET(switchtime);
465 td->td_runtime += runtime;
466 td->td_incruntime += runtime;
467 PCPU_SET(switchtime, new_switchtime);
468 PCPU_SET(switchticks, ticks);
469 PCPU_INC(cnt.v_swtch);
471 /* Save our resource usage in our process. */
472 td->td_ru.ru_nvcsw++;
474 rucollect(&p->p_ru, &td->td_ru);
478 td->td_state = TDS_INACTIVE;
480 witness_thread_exit(td);
482 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
484 panic("I'm a teapot!");
489 * Do any thread specific cleanups that may be needed in wait()
490 * called with Giant, proc and schedlock not held.
493 thread_wait(struct proc *p)
497 mtx_assert(&Giant, MA_NOTOWNED);
498 KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()"));
499 td = FIRST_THREAD_IN_PROC(p);
500 /* Lock the last thread so we spin until it exits cpu_throw(). */
503 /* Wait for any remaining threads to exit cpu_throw(). */
504 while (p->p_exitthreads)
505 sched_relinquish(curthread);
506 lock_profile_thread_exit(td);
507 cpuset_rel(td->td_cpuset);
508 td->td_cpuset = NULL;
509 cpu_thread_clean(td);
510 crfree(td->td_ucred);
511 thread_reap(); /* check for zombie threads etc. */
515 * Link a thread to a process.
516 * set up anything that needs to be initialized for it to
517 * be used by the process.
520 thread_link(struct thread *td, struct proc *p)
524 * XXX This can't be enabled because it's called for proc0 before
525 * its lock has been created.
526 * PROC_LOCK_ASSERT(p, MA_OWNED);
528 td->td_state = TDS_INACTIVE;
530 td->td_flags = TDF_INMEM;
532 LIST_INIT(&td->td_contested);
533 LIST_INIT(&td->td_lprof[0]);
534 LIST_INIT(&td->td_lprof[1]);
535 sigqueue_init(&td->td_sigqueue, p);
536 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE);
537 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist);
542 * Convert a process with one thread to an unthreaded process.
545 thread_unthread(struct thread *td)
547 struct proc *p = td->td_proc;
549 KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads"));
550 p->p_flag &= ~P_HADTHREADS;
558 thread_unlink(struct thread *td)
560 struct proc *p = td->td_proc;
562 PROC_LOCK_ASSERT(p, MA_OWNED);
563 TAILQ_REMOVE(&p->p_threads, td, td_plist);
565 /* could clear a few other things here */
566 /* Must NOT clear links to proc! */
570 calc_remaining(struct proc *p, int mode)
574 PROC_LOCK_ASSERT(p, MA_OWNED);
575 PROC_SLOCK_ASSERT(p, MA_OWNED);
576 if (mode == SINGLE_EXIT)
577 remaining = p->p_numthreads;
578 else if (mode == SINGLE_BOUNDARY)
579 remaining = p->p_numthreads - p->p_boundary_count;
580 else if (mode == SINGLE_NO_EXIT)
581 remaining = p->p_numthreads - p->p_suspcount;
583 panic("calc_remaining: wrong mode %d", mode);
588 * Enforce single-threading.
590 * Returns 1 if the caller must abort (another thread is waiting to
591 * exit the process or similar). Process is locked!
592 * Returns 0 when you are successfully the only thread running.
593 * A process has successfully single threaded in the suspend mode when
594 * There are no threads in user mode. Threads in the kernel must be
595 * allowed to continue until they get to the user boundary. They may even
596 * copy out their return values and data before suspending. They may however be
597 * accelerated in reaching the user boundary as we will wake up
598 * any sleeping threads that are interruptable. (PCATCH).
601 thread_single(int mode)
606 int remaining, wakeup_swapper;
610 mtx_assert(&Giant, MA_NOTOWNED);
611 PROC_LOCK_ASSERT(p, MA_OWNED);
612 KASSERT((td != NULL), ("curthread is NULL"));
614 if ((p->p_flag & P_HADTHREADS) == 0)
617 /* Is someone already single threading? */
618 if (p->p_singlethread != NULL && p->p_singlethread != td)
621 if (mode == SINGLE_EXIT) {
622 p->p_flag |= P_SINGLE_EXIT;
623 p->p_flag &= ~P_SINGLE_BOUNDARY;
625 p->p_flag &= ~P_SINGLE_EXIT;
626 if (mode == SINGLE_BOUNDARY)
627 p->p_flag |= P_SINGLE_BOUNDARY;
629 p->p_flag &= ~P_SINGLE_BOUNDARY;
631 p->p_flag |= P_STOPPED_SINGLE;
633 p->p_singlethread = td;
634 remaining = calc_remaining(p, mode);
635 while (remaining != 1) {
636 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE)
639 FOREACH_THREAD_IN_PROC(p, td2) {
643 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK;
644 if (TD_IS_INHIBITED(td2)) {
647 if (TD_IS_SUSPENDED(td2))
649 thread_unsuspend_one(td2);
650 if (TD_ON_SLEEPQ(td2) &&
651 (td2->td_flags & TDF_SINTR))
653 sleepq_abort(td2, EINTR);
655 case SINGLE_BOUNDARY:
656 if (TD_IS_SUSPENDED(td2) &&
657 !(td2->td_flags & TDF_BOUNDARY))
659 thread_unsuspend_one(td2);
660 if (TD_ON_SLEEPQ(td2) &&
661 (td2->td_flags & TDF_SINTR))
663 sleepq_abort(td2, ERESTART);
666 if (TD_IS_SUSPENDED(td2) &&
667 !(td2->td_flags & TDF_BOUNDARY))
669 thread_unsuspend_one(td2);
670 if (TD_ON_SLEEPQ(td2) &&
671 (td2->td_flags & TDF_SINTR))
673 sleepq_abort(td2, ERESTART);
680 else if (TD_IS_RUNNING(td2) && td != td2) {
688 remaining = calc_remaining(p, mode);
691 * Maybe we suspended some threads.. was it enough?
698 * Wake us up when everyone else has suspended.
699 * In the mean time we suspend as well.
701 thread_suspend_switch(td);
702 remaining = calc_remaining(p, mode);
704 if (mode == SINGLE_EXIT) {
706 * We have gotten rid of all the other threads and we
707 * are about to either exit or exec. In either case,
708 * we try our utmost to revert to being a non-threaded
711 p->p_singlethread = NULL;
712 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT);
720 * Called in from locations that can safely check to see
721 * whether we have to suspend or at least throttle for a
722 * single-thread event (e.g. fork).
724 * Such locations include userret().
725 * If the "return_instead" argument is non zero, the thread must be able to
726 * accept 0 (caller may continue), or 1 (caller must abort) as a result.
728 * The 'return_instead' argument tells the function if it may do a
729 * thread_exit() or suspend, or whether the caller must abort and back
732 * If the thread that set the single_threading request has set the
733 * P_SINGLE_EXIT bit in the process flags then this call will never return
734 * if 'return_instead' is false, but will exit.
736 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0
737 *---------------+--------------------+---------------------
738 * 0 | returns 0 | returns 0 or 1
739 * | when ST ends | immediatly
740 *---------------+--------------------+---------------------
741 * 1 | thread exits | returns 1
743 * 0 = thread_exit() or suspension ok,
744 * other = return error instead of stopping the thread.
746 * While a full suspension is under effect, even a single threading
747 * thread would be suspended if it made this call (but it shouldn't).
748 * This call should only be made from places where
749 * thread_exit() would be safe as that may be the outcome unless
750 * return_instead is set.
753 thread_suspend_check(int return_instead)
761 mtx_assert(&Giant, MA_NOTOWNED);
762 PROC_LOCK_ASSERT(p, MA_OWNED);
763 while (P_SHOULDSTOP(p) ||
764 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) {
765 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
766 KASSERT(p->p_singlethread != NULL,
767 ("singlethread not set"));
769 * The only suspension in action is a
770 * single-threading. Single threader need not stop.
771 * XXX Should be safe to access unlocked
772 * as it can only be set to be true by us.
774 if (p->p_singlethread == td)
775 return (0); /* Exempt from stopping. */
777 if ((p->p_flag & P_SINGLE_EXIT) && return_instead)
780 /* Should we goto user boundary if we didn't come from there? */
781 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
782 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
786 * If the process is waiting for us to exit,
787 * this thread should just suicide.
788 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
790 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
802 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
803 if (p->p_numthreads == p->p_suspcount + 1) {
804 thread_lock(p->p_singlethread);
806 thread_unsuspend_one(p->p_singlethread);
807 thread_unlock(p->p_singlethread);
815 * When a thread suspends, it just
816 * gets taken off all queues.
818 thread_suspend_one(td);
819 if (return_instead == 0) {
820 p->p_boundary_count++;
821 td->td_flags |= TDF_BOUNDARY;
824 mi_switch(SW_INVOL | SWT_SUSPEND, NULL);
825 if (return_instead == 0)
826 td->td_flags &= ~TDF_BOUNDARY;
829 if (return_instead == 0) {
831 p->p_boundary_count--;
839 thread_suspend_switch(struct thread *td)
844 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
845 PROC_LOCK_ASSERT(p, MA_OWNED);
846 PROC_SLOCK_ASSERT(p, MA_OWNED);
848 * We implement thread_suspend_one in stages here to avoid
849 * dropping the proc lock while the thread lock is owned.
855 td->td_flags &= ~TDF_NEEDSUSPCHK;
856 TD_SET_SUSPENDED(td);
860 mi_switch(SW_VOL | SWT_SUSPEND, NULL);
868 thread_suspend_one(struct thread *td)
870 struct proc *p = td->td_proc;
872 PROC_SLOCK_ASSERT(p, MA_OWNED);
873 THREAD_LOCK_ASSERT(td, MA_OWNED);
874 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
876 td->td_flags &= ~TDF_NEEDSUSPCHK;
877 TD_SET_SUSPENDED(td);
882 thread_unsuspend_one(struct thread *td)
884 struct proc *p = td->td_proc;
886 PROC_SLOCK_ASSERT(p, MA_OWNED);
887 THREAD_LOCK_ASSERT(td, MA_OWNED);
888 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
889 TD_CLR_SUSPENDED(td);
891 return (setrunnable(td));
895 * Allow all threads blocked by single threading to continue running.
898 thread_unsuspend(struct proc *p)
903 PROC_LOCK_ASSERT(p, MA_OWNED);
904 PROC_SLOCK_ASSERT(p, MA_OWNED);
906 if (!P_SHOULDSTOP(p)) {
907 FOREACH_THREAD_IN_PROC(p, td) {
909 if (TD_IS_SUSPENDED(td)) {
910 wakeup_swapper |= thread_unsuspend_one(td);
914 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) &&
915 (p->p_numthreads == p->p_suspcount)) {
917 * Stopping everything also did the job for the single
918 * threading request. Now we've downgraded to single-threaded,
921 thread_lock(p->p_singlethread);
922 wakeup_swapper = thread_unsuspend_one(p->p_singlethread);
923 thread_unlock(p->p_singlethread);
930 * End the single threading mode..
933 thread_single_end(void)
941 PROC_LOCK_ASSERT(p, MA_OWNED);
942 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY);
944 p->p_singlethread = NULL;
947 * If there are other threads they may now run,
948 * unless of course there is a blanket 'stop order'
949 * on the process. The single threader must be allowed
950 * to continue however as this is a bad place to stop.
952 if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) {
953 FOREACH_THREAD_IN_PROC(p, td) {
955 if (TD_IS_SUSPENDED(td)) {
956 wakeup_swapper |= thread_unsuspend_one(td);
967 thread_find(struct proc *p, lwpid_t tid)
971 PROC_LOCK_ASSERT(p, MA_OWNED);
972 FOREACH_THREAD_IN_PROC(p, td) {
973 if (td->td_tid == tid)
979 /* Locate a thread by number; return with proc lock held. */
981 tdfind(lwpid_t tid, pid_t pid)
983 #define RUN_THRESH 16
987 rw_rlock(&tidhash_lock);
988 LIST_FOREACH(td, TIDHASH(tid), td_hash) {
989 if (td->td_tid == tid) {
990 if (pid != -1 && td->td_proc->p_pid != pid) {
994 PROC_LOCK(td->td_proc);
995 if (td->td_proc->p_state == PRS_NEW) {
996 PROC_UNLOCK(td->td_proc);
1000 if (run > RUN_THRESH) {
1001 if (rw_try_upgrade(&tidhash_lock)) {
1002 LIST_REMOVE(td, td_hash);
1003 LIST_INSERT_HEAD(TIDHASH(td->td_tid),
1005 rw_wunlock(&tidhash_lock);
1013 rw_runlock(&tidhash_lock);
1018 tidhash_add(struct thread *td)
1020 rw_wlock(&tidhash_lock);
1021 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
1022 rw_wunlock(&tidhash_lock);
1026 tidhash_remove(struct thread *td)
1028 rw_wlock(&tidhash_lock);
1029 LIST_REMOVE(td, td_hash);
1030 rw_wunlock(&tidhash_lock);