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/vmmeter.h>
55 #include <sys/cpuset.h>
57 #include <sys/pmckern.h>
60 #include <security/audit/audit.h>
63 #include <vm/vm_extern.h>
65 #include <vm/vm_domain.h>
66 #include <sys/eventhandler.h>
68 SDT_PROVIDER_DECLARE(proc);
69 SDT_PROBE_DEFINE(proc, , , lwp__exit);
72 * thread related storage.
74 static uma_zone_t thread_zone;
76 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads);
77 static struct mtx zombie_lock;
78 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN);
80 static void thread_zombie(struct thread *);
81 static int thread_unsuspend_one(struct thread *td, struct proc *p,
84 #define TID_BUFFER_SIZE 1024
87 static struct unrhdr *tid_unrhdr;
88 static lwpid_t tid_buffer[TID_BUFFER_SIZE];
89 static int tid_head, tid_tail;
90 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash");
92 struct tidhashhead *tidhashtbl;
94 struct rwlock tidhash_lock;
101 tid = alloc_unr(tid_unrhdr);
105 if (tid_head == tid_tail) {
106 mtx_unlock(&tid_lock);
109 tid = tid_buffer[tid_head];
110 tid_head = (tid_head + 1) % TID_BUFFER_SIZE;
111 mtx_unlock(&tid_lock);
116 tid_free(lwpid_t tid)
118 lwpid_t tmp_tid = -1;
121 if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) {
122 tmp_tid = tid_buffer[tid_head];
123 tid_head = (tid_head + 1) % TID_BUFFER_SIZE;
125 tid_buffer[tid_tail] = tid;
126 tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE;
127 mtx_unlock(&tid_lock);
129 free_unr(tid_unrhdr, tmp_tid);
133 * Prepare a thread for use.
136 thread_ctor(void *mem, int size, void *arg, int flags)
140 td = (struct thread *)mem;
141 td->td_state = TDS_INACTIVE;
142 td->td_oncpu = NOCPU;
144 td->td_tid = tid_alloc();
147 * Note that td_critnest begins life as 1 because the thread is not
148 * running and is thereby implicitly waiting to be on the receiving
149 * end of a context switch.
152 td->td_lend_user_pri = PRI_MAX;
153 EVENTHANDLER_INVOKE(thread_ctor, td);
155 audit_thread_alloc(td);
157 umtx_thread_alloc(td);
162 * Reclaim a thread after use.
165 thread_dtor(void *mem, int size, void *arg)
169 td = (struct thread *)mem;
172 /* Verify that this thread is in a safe state to free. */
173 switch (td->td_state) {
179 * We must never unlink a thread that is in one of
180 * these states, because it is currently active.
182 panic("bad state for thread unlinking");
187 panic("bad thread state");
192 audit_thread_free(td);
194 /* Free all OSD associated to this thread. */
196 td_softdep_cleanup(td);
197 MPASS(td->td_su == NULL);
199 EVENTHANDLER_INVOKE(thread_dtor, td);
200 tid_free(td->td_tid);
204 * Initialize type-stable parts of a thread (when newly created).
207 thread_init(void *mem, int size, int flags)
211 td = (struct thread *)mem;
213 td->td_sleepqueue = sleepq_alloc();
214 td->td_turnstile = turnstile_alloc();
216 EVENTHANDLER_INVOKE(thread_init, td);
217 umtx_thread_init(td);
224 * Tear down type-stable parts of a thread (just before being discarded).
227 thread_fini(void *mem, int size)
231 td = (struct thread *)mem;
232 EVENTHANDLER_INVOKE(thread_fini, td);
233 rlqentry_free(td->td_rlqe);
234 turnstile_free(td->td_turnstile);
235 sleepq_free(td->td_sleepqueue);
236 umtx_thread_fini(td);
241 * For a newly created process,
242 * link up all the structures and its initial threads etc.
244 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc.
245 * proc_dtor() (should go away)
249 proc_linkup0(struct proc *p, struct thread *td)
251 TAILQ_INIT(&p->p_threads); /* all threads in proc */
256 proc_linkup(struct proc *p, struct thread *td)
259 sigqueue_init(&p->p_sigqueue, p);
260 p->p_ksi = ksiginfo_alloc(1);
261 if (p->p_ksi != NULL) {
262 /* XXX p_ksi may be null if ksiginfo zone is not ready */
263 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS;
265 LIST_INIT(&p->p_mqnotifier);
271 * Initialize global thread allocation resources.
277 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
280 * pid_max cannot be greater than PID_MAX.
281 * leave one number for thread0.
283 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock);
285 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
286 thread_ctor, thread_dtor, thread_init, thread_fini,
287 32 - 1, UMA_ZONE_NOFREE);
288 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash);
289 rw_init(&tidhash_lock, "tidhash");
293 * Place an unused thread on the zombie list.
294 * Use the slpq as that must be unused by now.
297 thread_zombie(struct thread *td)
299 mtx_lock_spin(&zombie_lock);
300 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq);
301 mtx_unlock_spin(&zombie_lock);
305 * Release a thread that has exited after cpu_throw().
308 thread_stash(struct thread *td)
310 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1);
315 * Reap zombie resources.
320 struct thread *td_first, *td_next;
323 * Don't even bother to lock if none at this instant,
324 * we really don't care about the next instant.
326 if (!TAILQ_EMPTY(&zombie_threads)) {
327 mtx_lock_spin(&zombie_lock);
328 td_first = TAILQ_FIRST(&zombie_threads);
330 TAILQ_INIT(&zombie_threads);
331 mtx_unlock_spin(&zombie_lock);
333 td_next = TAILQ_NEXT(td_first, td_slpq);
334 thread_cow_free(td_first);
335 thread_free(td_first);
345 thread_alloc(int pages)
349 thread_reap(); /* check if any zombies to get */
351 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK);
352 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
353 if (!vm_thread_new(td, pages)) {
354 uma_zfree(thread_zone, td);
357 cpu_thread_alloc(td);
358 vm_domain_policy_init(&td->td_vm_dom_policy);
363 thread_alloc_stack(struct thread *td, int pages)
366 KASSERT(td->td_kstack == 0,
367 ("thread_alloc_stack called on a thread with kstack"));
368 if (!vm_thread_new(td, pages))
370 cpu_thread_alloc(td);
375 * Deallocate a thread.
378 thread_free(struct thread *td)
381 lock_profile_thread_exit(td);
383 cpuset_rel(td->td_cpuset);
384 td->td_cpuset = NULL;
386 if (td->td_kstack != 0)
387 vm_thread_dispose(td);
388 vm_domain_policy_cleanup(&td->td_vm_dom_policy);
389 callout_drain(&td->td_slpcallout);
390 uma_zfree(thread_zone, td);
394 thread_cow_get_proc(struct thread *newtd, struct proc *p)
397 PROC_LOCK_ASSERT(p, MA_OWNED);
398 newtd->td_ucred = crhold(p->p_ucred);
399 newtd->td_limit = lim_hold(p->p_limit);
400 newtd->td_cowgen = p->p_cowgen;
404 thread_cow_get(struct thread *newtd, struct thread *td)
407 newtd->td_ucred = crhold(td->td_ucred);
408 newtd->td_limit = lim_hold(td->td_limit);
409 newtd->td_cowgen = td->td_cowgen;
413 thread_cow_free(struct thread *td)
416 if (td->td_ucred != NULL)
417 crfree(td->td_ucred);
418 if (td->td_limit != NULL)
419 lim_free(td->td_limit);
423 thread_cow_update(struct thread *td)
426 struct ucred *oldcred;
427 struct plimit *oldlimit;
433 if (td->td_ucred != p->p_ucred) {
434 oldcred = td->td_ucred;
435 td->td_ucred = crhold(p->p_ucred);
437 if (td->td_limit != p->p_limit) {
438 oldlimit = td->td_limit;
439 td->td_limit = lim_hold(p->p_limit);
441 td->td_cowgen = p->p_cowgen;
445 if (oldlimit != NULL)
450 * Discard the current thread and exit from its context.
451 * Always called with scheduler locked.
453 * Because we can't free a thread while we're operating under its context,
454 * push the current thread into our CPU's deadthread holder. This means
455 * we needn't worry about someone else grabbing our context before we
461 uint64_t runtime, new_switchtime;
470 PROC_SLOCK_ASSERT(p, MA_OWNED);
471 mtx_assert(&Giant, MA_NOTOWNED);
473 PROC_LOCK_ASSERT(p, MA_OWNED);
474 KASSERT(p != NULL, ("thread exiting without a process"));
475 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
476 (long)p->p_pid, td->td_name);
477 SDT_PROBE0(proc, , , lwp__exit);
478 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
481 AUDIT_SYSCALL_EXIT(0, td);
484 * drop FPU & debug register state storage, or any other
485 * architecture specific resources that
486 * would not be on a new untouched process.
491 * The last thread is left attached to the process
492 * So that the whole bundle gets recycled. Skip
493 * all this stuff if we never had threads.
494 * EXIT clears all sign of other threads when
495 * it goes to single threading, so the last thread always
496 * takes the short path.
498 if (p->p_flag & P_HADTHREADS) {
499 if (p->p_numthreads > 1) {
500 atomic_add_int(&td->td_proc->p_exitthreads, 1);
502 td2 = FIRST_THREAD_IN_PROC(p);
503 sched_exit_thread(td2, td);
506 * The test below is NOT true if we are the
507 * sole exiting thread. P_STOPPED_SINGLE is unset
508 * in exit1() after it is the only survivor.
510 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
511 if (p->p_numthreads == p->p_suspcount) {
512 thread_lock(p->p_singlethread);
513 wakeup_swapper = thread_unsuspend_one(
514 p->p_singlethread, p, false);
515 thread_unlock(p->p_singlethread);
521 PCPU_SET(deadthread, td);
524 * The last thread is exiting.. but not through exit()
526 panic ("thread_exit: Last thread exiting on its own");
531 * If this thread is part of a process that is being tracked by hwpmc(4),
532 * inform the module of the thread's impending exit.
534 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
535 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
542 /* Do the same timestamp bookkeeping that mi_switch() would do. */
543 new_switchtime = cpu_ticks();
544 runtime = new_switchtime - PCPU_GET(switchtime);
545 td->td_runtime += runtime;
546 td->td_incruntime += runtime;
547 PCPU_SET(switchtime, new_switchtime);
548 PCPU_SET(switchticks, ticks);
551 /* Save our resource usage in our process. */
552 td->td_ru.ru_nvcsw++;
554 rucollect(&p->p_ru, &td->td_ru);
557 td->td_state = TDS_INACTIVE;
559 witness_thread_exit(td);
561 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
563 panic("I'm a teapot!");
568 * Do any thread specific cleanups that may be needed in wait()
569 * called with Giant, proc and schedlock not held.
572 thread_wait(struct proc *p)
576 mtx_assert(&Giant, MA_NOTOWNED);
577 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()"));
578 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking"));
579 td = FIRST_THREAD_IN_PROC(p);
580 /* Lock the last thread so we spin until it exits cpu_throw(). */
583 lock_profile_thread_exit(td);
584 cpuset_rel(td->td_cpuset);
585 td->td_cpuset = NULL;
586 cpu_thread_clean(td);
588 callout_drain(&td->td_slpcallout);
589 thread_reap(); /* check for zombie threads etc. */
593 * Link a thread to a process.
594 * set up anything that needs to be initialized for it to
595 * be used by the process.
598 thread_link(struct thread *td, struct proc *p)
602 * XXX This can't be enabled because it's called for proc0 before
603 * its lock has been created.
604 * PROC_LOCK_ASSERT(p, MA_OWNED);
606 td->td_state = TDS_INACTIVE;
608 td->td_flags = TDF_INMEM;
610 LIST_INIT(&td->td_contested);
611 LIST_INIT(&td->td_lprof[0]);
612 LIST_INIT(&td->td_lprof[1]);
613 sigqueue_init(&td->td_sigqueue, p);
614 callout_init(&td->td_slpcallout, 1);
615 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist);
624 thread_unlink(struct thread *td)
626 struct proc *p = td->td_proc;
628 PROC_LOCK_ASSERT(p, MA_OWNED);
629 TAILQ_REMOVE(&p->p_threads, td, td_plist);
631 /* could clear a few other things here */
632 /* Must NOT clear links to proc! */
636 calc_remaining(struct proc *p, int mode)
640 PROC_LOCK_ASSERT(p, MA_OWNED);
641 PROC_SLOCK_ASSERT(p, MA_OWNED);
642 if (mode == SINGLE_EXIT)
643 remaining = p->p_numthreads;
644 else if (mode == SINGLE_BOUNDARY)
645 remaining = p->p_numthreads - p->p_boundary_count;
646 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC)
647 remaining = p->p_numthreads - p->p_suspcount;
649 panic("calc_remaining: wrong mode %d", mode);
654 remain_for_mode(int mode)
657 return (mode == SINGLE_ALLPROC ? 0 : 1);
661 weed_inhib(int mode, struct thread *td2, struct proc *p)
665 PROC_LOCK_ASSERT(p, MA_OWNED);
666 PROC_SLOCK_ASSERT(p, MA_OWNED);
667 THREAD_LOCK_ASSERT(td2, MA_OWNED);
672 if (TD_IS_SUSPENDED(td2))
673 wakeup_swapper |= thread_unsuspend_one(td2, p, true);
674 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0)
675 wakeup_swapper |= sleepq_abort(td2, EINTR);
677 case SINGLE_BOUNDARY:
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 * It is safe to access p->p_singlethread unlocked
917 * because it can only be set to our address 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"));
936 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) !=
937 (TDF_SEINTR | TDF_SERESTART),
938 ("both TDF_SEINTR and TDF_SERESTART"));
939 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0);
943 * If the process is waiting for us to exit,
944 * this thread should just suicide.
945 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
947 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
951 * Allow Linux emulation layer to do some work
952 * before thread suicide.
954 if (__predict_false(p->p_sysent->sv_thread_detach != NULL))
955 (p->p_sysent->sv_thread_detach)(td);
956 umtx_thread_exit(td);
958 panic("stopped thread did not exit");
963 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
964 if (p->p_numthreads == p->p_suspcount + 1) {
965 thread_lock(p->p_singlethread);
966 wakeup_swapper = thread_unsuspend_one(
967 p->p_singlethread, p, false);
968 thread_unlock(p->p_singlethread);
976 * When a thread suspends, it just
977 * gets taken off all queues.
979 thread_suspend_one(td);
980 if (return_instead == 0) {
981 p->p_boundary_count++;
982 td->td_flags |= TDF_BOUNDARY;
985 mi_switch(SW_INVOL | SWT_SUSPEND, NULL);
993 thread_suspend_switch(struct thread *td, struct proc *p)
996 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
997 PROC_LOCK_ASSERT(p, MA_OWNED);
998 PROC_SLOCK_ASSERT(p, MA_OWNED);
1000 * We implement thread_suspend_one in stages here to avoid
1001 * dropping the proc lock while the thread lock is owned.
1003 if (p == td->td_proc) {
1009 td->td_flags &= ~TDF_NEEDSUSPCHK;
1010 TD_SET_SUSPENDED(td);
1014 mi_switch(SW_VOL | SWT_SUSPEND, NULL);
1022 thread_suspend_one(struct thread *td)
1027 PROC_SLOCK_ASSERT(p, MA_OWNED);
1028 THREAD_LOCK_ASSERT(td, MA_OWNED);
1029 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
1031 td->td_flags &= ~TDF_NEEDSUSPCHK;
1032 TD_SET_SUSPENDED(td);
1037 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary)
1040 THREAD_LOCK_ASSERT(td, MA_OWNED);
1041 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
1042 TD_CLR_SUSPENDED(td);
1043 td->td_flags &= ~TDF_ALLPROCSUSP;
1044 if (td->td_proc == p) {
1045 PROC_SLOCK_ASSERT(p, MA_OWNED);
1047 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) {
1048 td->td_flags &= ~TDF_BOUNDARY;
1049 p->p_boundary_count--;
1052 return (setrunnable(td));
1056 * Allow all threads blocked by single threading to continue running.
1059 thread_unsuspend(struct proc *p)
1064 PROC_LOCK_ASSERT(p, MA_OWNED);
1065 PROC_SLOCK_ASSERT(p, MA_OWNED);
1067 if (!P_SHOULDSTOP(p)) {
1068 FOREACH_THREAD_IN_PROC(p, td) {
1070 if (TD_IS_SUSPENDED(td)) {
1071 wakeup_swapper |= thread_unsuspend_one(td, p,
1076 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
1077 p->p_numthreads == p->p_suspcount) {
1079 * Stopping everything also did the job for the single
1080 * threading request. Now we've downgraded to single-threaded,
1083 if (p->p_singlethread->td_proc == p) {
1084 thread_lock(p->p_singlethread);
1085 wakeup_swapper = thread_unsuspend_one(
1086 p->p_singlethread, p, false);
1087 thread_unlock(p->p_singlethread);
1095 * End the single threading mode..
1098 thread_single_end(struct proc *p, int mode)
1103 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
1104 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
1105 ("invalid mode %d", mode));
1106 PROC_LOCK_ASSERT(p, MA_OWNED);
1107 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) ||
1108 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0),
1109 ("mode %d does not match P_TOTAL_STOP", mode));
1110 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread,
1111 ("thread_single_end from other thread %p %p",
1112 curthread, p->p_singlethread));
1113 KASSERT(mode != SINGLE_BOUNDARY ||
1114 (p->p_flag & P_SINGLE_BOUNDARY) != 0,
1115 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag));
1116 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY |
1119 p->p_singlethread = NULL;
1122 * If there are other threads they may now run,
1123 * unless of course there is a blanket 'stop order'
1124 * on the process. The single threader must be allowed
1125 * to continue however as this is a bad place to stop.
1127 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) {
1128 FOREACH_THREAD_IN_PROC(p, td) {
1130 if (TD_IS_SUSPENDED(td)) {
1131 wakeup_swapper |= thread_unsuspend_one(td, p,
1132 mode == SINGLE_BOUNDARY);
1137 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0,
1138 ("inconsistent boundary count %d", p->p_boundary_count));
1145 thread_find(struct proc *p, lwpid_t tid)
1149 PROC_LOCK_ASSERT(p, MA_OWNED);
1150 FOREACH_THREAD_IN_PROC(p, td) {
1151 if (td->td_tid == tid)
1157 /* Locate a thread by number; return with proc lock held. */
1159 tdfind(lwpid_t tid, pid_t pid)
1161 #define RUN_THRESH 16
1165 rw_rlock(&tidhash_lock);
1166 LIST_FOREACH(td, TIDHASH(tid), td_hash) {
1167 if (td->td_tid == tid) {
1168 if (pid != -1 && td->td_proc->p_pid != pid) {
1172 PROC_LOCK(td->td_proc);
1173 if (td->td_proc->p_state == PRS_NEW) {
1174 PROC_UNLOCK(td->td_proc);
1178 if (run > RUN_THRESH) {
1179 if (rw_try_upgrade(&tidhash_lock)) {
1180 LIST_REMOVE(td, td_hash);
1181 LIST_INSERT_HEAD(TIDHASH(td->td_tid),
1183 rw_wunlock(&tidhash_lock);
1191 rw_runlock(&tidhash_lock);
1196 tidhash_add(struct thread *td)
1198 rw_wlock(&tidhash_lock);
1199 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
1200 rw_wunlock(&tidhash_lock);
1204 tidhash_remove(struct thread *td)
1206 rw_wlock(&tidhash_lock);
1207 LIST_REMOVE(td, td_hash);
1208 rw_wunlock(&tidhash_lock);