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. */
195 td_softdep_cleanup(td);
196 MPASS(td->td_su == NULL);
198 EVENTHANDLER_INVOKE(thread_dtor, td);
199 tid_free(td->td_tid);
203 * Initialize type-stable parts of a thread (when newly created).
206 thread_init(void *mem, int size, int flags)
210 td = (struct thread *)mem;
212 td->td_sleepqueue = sleepq_alloc();
213 td->td_turnstile = turnstile_alloc();
215 EVENTHANDLER_INVOKE(thread_init, td);
216 umtx_thread_init(td);
223 * Tear down type-stable parts of a thread (just before being discarded).
226 thread_fini(void *mem, int size)
230 td = (struct thread *)mem;
231 EVENTHANDLER_INVOKE(thread_fini, td);
232 rlqentry_free(td->td_rlqe);
233 turnstile_free(td->td_turnstile);
234 sleepq_free(td->td_sleepqueue);
235 umtx_thread_fini(td);
240 * For a newly created process,
241 * link up all the structures and its initial threads etc.
243 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc.
244 * proc_dtor() (should go away)
248 proc_linkup0(struct proc *p, struct thread *td)
250 TAILQ_INIT(&p->p_threads); /* all threads in proc */
255 proc_linkup(struct proc *p, struct thread *td)
258 sigqueue_init(&p->p_sigqueue, p);
259 p->p_ksi = ksiginfo_alloc(1);
260 if (p->p_ksi != NULL) {
261 /* XXX p_ksi may be null if ksiginfo zone is not ready */
262 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS;
264 LIST_INIT(&p->p_mqnotifier);
270 * Initialize global thread allocation resources.
276 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
279 * pid_max cannot be greater than PID_MAX.
280 * leave one number for thread0.
282 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock);
284 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
285 thread_ctor, thread_dtor, thread_init, thread_fini,
286 32 - 1, UMA_ZONE_NOFREE);
287 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash);
288 rw_init(&tidhash_lock, "tidhash");
292 * Place an unused thread on the zombie list.
293 * Use the slpq as that must be unused by now.
296 thread_zombie(struct thread *td)
298 mtx_lock_spin(&zombie_lock);
299 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq);
300 mtx_unlock_spin(&zombie_lock);
304 * Release a thread that has exited after cpu_throw().
307 thread_stash(struct thread *td)
309 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1);
314 * Reap zombie resources.
319 struct thread *td_first, *td_next;
322 * Don't even bother to lock if none at this instant,
323 * we really don't care about the next instant.
325 if (!TAILQ_EMPTY(&zombie_threads)) {
326 mtx_lock_spin(&zombie_lock);
327 td_first = TAILQ_FIRST(&zombie_threads);
329 TAILQ_INIT(&zombie_threads);
330 mtx_unlock_spin(&zombie_lock);
332 td_next = TAILQ_NEXT(td_first, td_slpq);
333 thread_cow_free(td_first);
334 thread_free(td_first);
344 thread_alloc(int pages)
348 thread_reap(); /* check if any zombies to get */
350 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK);
351 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
352 if (!vm_thread_new(td, pages)) {
353 uma_zfree(thread_zone, td);
356 cpu_thread_alloc(td);
357 vm_domain_policy_init(&td->td_vm_dom_policy);
362 thread_alloc_stack(struct thread *td, int pages)
365 KASSERT(td->td_kstack == 0,
366 ("thread_alloc_stack called on a thread with kstack"));
367 if (!vm_thread_new(td, pages))
369 cpu_thread_alloc(td);
374 * Deallocate a thread.
377 thread_free(struct thread *td)
380 lock_profile_thread_exit(td);
382 cpuset_rel(td->td_cpuset);
383 td->td_cpuset = NULL;
385 if (td->td_kstack != 0)
386 vm_thread_dispose(td);
387 vm_domain_policy_cleanup(&td->td_vm_dom_policy);
388 callout_drain(&td->td_slpcallout);
389 uma_zfree(thread_zone, td);
393 thread_cow_get_proc(struct thread *newtd, struct proc *p)
396 PROC_LOCK_ASSERT(p, MA_OWNED);
397 newtd->td_ucred = crhold(p->p_ucred);
398 newtd->td_limit = lim_hold(p->p_limit);
399 newtd->td_cowgen = p->p_cowgen;
403 thread_cow_get(struct thread *newtd, struct thread *td)
406 newtd->td_ucred = crhold(td->td_ucred);
407 newtd->td_limit = lim_hold(td->td_limit);
408 newtd->td_cowgen = td->td_cowgen;
412 thread_cow_free(struct thread *td)
415 if (td->td_ucred != NULL)
416 crfree(td->td_ucred);
417 if (td->td_limit != NULL)
418 lim_free(td->td_limit);
422 thread_cow_update(struct thread *td)
425 struct ucred *oldcred;
426 struct plimit *oldlimit;
432 if (td->td_ucred != p->p_ucred) {
433 oldcred = td->td_ucred;
434 td->td_ucred = crhold(p->p_ucred);
436 if (td->td_limit != p->p_limit) {
437 oldlimit = td->td_limit;
438 td->td_limit = lim_hold(p->p_limit);
440 td->td_cowgen = p->p_cowgen;
444 if (oldlimit != NULL)
449 * Discard the current thread and exit from its context.
450 * Always called with scheduler locked.
452 * Because we can't free a thread while we're operating under its context,
453 * push the current thread into our CPU's deadthread holder. This means
454 * we needn't worry about someone else grabbing our context before we
460 uint64_t runtime, new_switchtime;
469 PROC_SLOCK_ASSERT(p, MA_OWNED);
470 mtx_assert(&Giant, MA_NOTOWNED);
472 PROC_LOCK_ASSERT(p, MA_OWNED);
473 KASSERT(p != NULL, ("thread exiting without a process"));
474 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
475 (long)p->p_pid, td->td_name);
476 SDT_PROBE0(proc, , , lwp__exit);
477 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
480 AUDIT_SYSCALL_EXIT(0, td);
483 * drop FPU & debug register state storage, or any other
484 * architecture specific resources that
485 * would not be on a new untouched process.
490 * The last thread is left attached to the process
491 * So that the whole bundle gets recycled. Skip
492 * all this stuff if we never had threads.
493 * EXIT clears all sign of other threads when
494 * it goes to single threading, so the last thread always
495 * takes the short path.
497 if (p->p_flag & P_HADTHREADS) {
498 if (p->p_numthreads > 1) {
499 atomic_add_int(&td->td_proc->p_exitthreads, 1);
501 td2 = FIRST_THREAD_IN_PROC(p);
502 sched_exit_thread(td2, td);
505 * The test below is NOT true if we are the
506 * sole exiting thread. P_STOPPED_SINGLE is unset
507 * in exit1() after it is the only survivor.
509 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
510 if (p->p_numthreads == p->p_suspcount) {
511 thread_lock(p->p_singlethread);
512 wakeup_swapper = thread_unsuspend_one(
513 p->p_singlethread, p, false);
514 thread_unlock(p->p_singlethread);
520 PCPU_SET(deadthread, td);
523 * The last thread is exiting.. but not through exit()
525 panic ("thread_exit: Last thread exiting on its own");
530 * If this thread is part of a process that is being tracked by hwpmc(4),
531 * inform the module of the thread's impending exit.
533 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
534 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
541 /* Do the same timestamp bookkeeping that mi_switch() would do. */
542 new_switchtime = cpu_ticks();
543 runtime = new_switchtime - PCPU_GET(switchtime);
544 td->td_runtime += runtime;
545 td->td_incruntime += runtime;
546 PCPU_SET(switchtime, new_switchtime);
547 PCPU_SET(switchticks, ticks);
548 PCPU_INC(cnt.v_swtch);
550 /* Save our resource usage in our process. */
551 td->td_ru.ru_nvcsw++;
553 rucollect(&p->p_ru, &td->td_ru);
556 td->td_state = TDS_INACTIVE;
558 witness_thread_exit(td);
560 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
562 panic("I'm a teapot!");
567 * Do any thread specific cleanups that may be needed in wait()
568 * called with Giant, proc and schedlock not held.
571 thread_wait(struct proc *p)
575 mtx_assert(&Giant, MA_NOTOWNED);
576 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()"));
577 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking"));
578 td = FIRST_THREAD_IN_PROC(p);
579 /* Lock the last thread so we spin until it exits cpu_throw(). */
582 lock_profile_thread_exit(td);
583 cpuset_rel(td->td_cpuset);
584 td->td_cpuset = NULL;
585 cpu_thread_clean(td);
587 callout_drain(&td->td_slpcallout);
588 thread_reap(); /* check for zombie threads etc. */
592 * Link a thread to a process.
593 * set up anything that needs to be initialized for it to
594 * be used by the process.
597 thread_link(struct thread *td, struct proc *p)
601 * XXX This can't be enabled because it's called for proc0 before
602 * its lock has been created.
603 * PROC_LOCK_ASSERT(p, MA_OWNED);
605 td->td_state = TDS_INACTIVE;
607 td->td_flags = TDF_INMEM;
609 LIST_INIT(&td->td_contested);
610 LIST_INIT(&td->td_lprof[0]);
611 LIST_INIT(&td->td_lprof[1]);
612 sigqueue_init(&td->td_sigqueue, p);
613 callout_init(&td->td_slpcallout, 1);
614 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist);
623 thread_unlink(struct thread *td)
625 struct proc *p = td->td_proc;
627 PROC_LOCK_ASSERT(p, MA_OWNED);
628 TAILQ_REMOVE(&p->p_threads, td, td_plist);
630 /* could clear a few other things here */
631 /* Must NOT clear links to proc! */
635 calc_remaining(struct proc *p, int mode)
639 PROC_LOCK_ASSERT(p, MA_OWNED);
640 PROC_SLOCK_ASSERT(p, MA_OWNED);
641 if (mode == SINGLE_EXIT)
642 remaining = p->p_numthreads;
643 else if (mode == SINGLE_BOUNDARY)
644 remaining = p->p_numthreads - p->p_boundary_count;
645 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC)
646 remaining = p->p_numthreads - p->p_suspcount;
648 panic("calc_remaining: wrong mode %d", mode);
653 remain_for_mode(int mode)
656 return (mode == SINGLE_ALLPROC ? 0 : 1);
660 weed_inhib(int mode, struct thread *td2, struct proc *p)
664 PROC_LOCK_ASSERT(p, MA_OWNED);
665 PROC_SLOCK_ASSERT(p, MA_OWNED);
666 THREAD_LOCK_ASSERT(td2, MA_OWNED);
671 if (TD_IS_SUSPENDED(td2))
672 wakeup_swapper |= thread_unsuspend_one(td2, p, true);
673 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0)
674 wakeup_swapper |= sleepq_abort(td2, EINTR);
676 case SINGLE_BOUNDARY:
678 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0)
679 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
680 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0)
681 wakeup_swapper |= sleepq_abort(td2, ERESTART);
685 * ALLPROC suspend tries to avoid spurious EINTR for
686 * threads sleeping interruptable, by suspending the
687 * thread directly, similarly to sig_suspend_threads().
688 * Since such sleep is not performed at the user
689 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP
690 * is used to avoid immediate un-suspend.
692 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY |
693 TDF_ALLPROCSUSP)) == 0)
694 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
695 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) {
696 if ((td2->td_flags & TDF_SBDRY) == 0) {
697 thread_suspend_one(td2);
698 td2->td_flags |= TDF_ALLPROCSUSP;
700 wakeup_swapper |= sleepq_abort(td2, ERESTART);
705 return (wakeup_swapper);
709 * Enforce single-threading.
711 * Returns 1 if the caller must abort (another thread is waiting to
712 * exit the process or similar). Process is locked!
713 * Returns 0 when you are successfully the only thread running.
714 * A process has successfully single threaded in the suspend mode when
715 * There are no threads in user mode. Threads in the kernel must be
716 * allowed to continue until they get to the user boundary. They may even
717 * copy out their return values and data before suspending. They may however be
718 * accelerated in reaching the user boundary as we will wake up
719 * any sleeping threads that are interruptable. (PCATCH).
722 thread_single(struct proc *p, int mode)
726 int remaining, wakeup_swapper;
729 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
730 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
731 ("invalid mode %d", mode));
733 * If allowing non-ALLPROC singlethreading for non-curproc
734 * callers, calc_remaining() and remain_for_mode() should be
735 * adjusted to also account for td->td_proc != p. For now
736 * this is not implemented because it is not used.
738 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) ||
739 (mode != SINGLE_ALLPROC && td->td_proc == p),
740 ("mode %d proc %p curproc %p", mode, p, td->td_proc));
741 mtx_assert(&Giant, MA_NOTOWNED);
742 PROC_LOCK_ASSERT(p, MA_OWNED);
744 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC)
747 /* Is someone already single threading? */
748 if (p->p_singlethread != NULL && p->p_singlethread != td)
751 if (mode == SINGLE_EXIT) {
752 p->p_flag |= P_SINGLE_EXIT;
753 p->p_flag &= ~P_SINGLE_BOUNDARY;
755 p->p_flag &= ~P_SINGLE_EXIT;
756 if (mode == SINGLE_BOUNDARY)
757 p->p_flag |= P_SINGLE_BOUNDARY;
759 p->p_flag &= ~P_SINGLE_BOUNDARY;
761 if (mode == SINGLE_ALLPROC)
762 p->p_flag |= P_TOTAL_STOP;
763 p->p_flag |= P_STOPPED_SINGLE;
765 p->p_singlethread = td;
766 remaining = calc_remaining(p, mode);
767 while (remaining != remain_for_mode(mode)) {
768 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE)
771 FOREACH_THREAD_IN_PROC(p, td2) {
775 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK;
776 if (TD_IS_INHIBITED(td2)) {
777 wakeup_swapper |= weed_inhib(mode, td2, p);
779 } else if (TD_IS_RUNNING(td2) && td != td2) {
787 remaining = calc_remaining(p, mode);
790 * Maybe we suspended some threads.. was it enough?
792 if (remaining == remain_for_mode(mode))
797 * Wake us up when everyone else has suspended.
798 * In the mean time we suspend as well.
800 thread_suspend_switch(td, p);
801 remaining = calc_remaining(p, mode);
803 if (mode == SINGLE_EXIT) {
805 * Convert the process to an unthreaded process. The
806 * SINGLE_EXIT is called by exit1() or execve(), in
807 * both cases other threads must be retired.
809 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads"));
810 p->p_singlethread = NULL;
811 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS);
814 * Wait for any remaining threads to exit cpu_throw().
816 while (p->p_exitthreads != 0) {
819 sched_relinquish(td);
823 } else if (mode == SINGLE_BOUNDARY) {
825 * Wait until all suspended threads are removed from
826 * the processors. The thread_suspend_check()
827 * increments p_boundary_count while it is still
828 * running, which makes it possible for the execve()
829 * to destroy vmspace while our other threads are
830 * still using the address space.
832 * We lock the thread, which is only allowed to
833 * succeed after context switch code finished using
836 FOREACH_THREAD_IN_PROC(p, td2) {
840 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0,
841 ("td %p not on boundary", td2));
842 KASSERT(TD_IS_SUSPENDED(td2),
843 ("td %p is not suspended", td2));
852 thread_suspend_check_needed(void)
859 PROC_LOCK_ASSERT(p, MA_OWNED);
860 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 &&
861 (td->td_dbgflags & TDB_SUSPEND) != 0));
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 | immediately
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)
906 mtx_assert(&Giant, MA_NOTOWNED);
907 PROC_LOCK_ASSERT(p, MA_OWNED);
908 while (thread_suspend_check_needed()) {
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 * It is safe to access p->p_singlethread unlocked
916 * because it can only be set to our address 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)
930 * Ignore suspend requests if they are deferred.
932 if ((td->td_flags & TDF_SBDRY) != 0) {
933 KASSERT(return_instead,
934 ("TDF_SBDRY set for unsafe thread_suspend_check"));
935 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) !=
936 (TDF_SEINTR | TDF_SERESTART),
937 ("both TDF_SEINTR and TDF_SERESTART"));
938 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0);
942 * If the process is waiting for us to exit,
943 * this thread should just suicide.
944 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
946 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
950 * Allow Linux emulation layer to do some work
951 * before thread suicide.
953 if (__predict_false(p->p_sysent->sv_thread_detach != NULL))
954 (p->p_sysent->sv_thread_detach)(td);
955 umtx_thread_exit(td);
957 panic("stopped thread did not exit");
962 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
963 if (p->p_numthreads == p->p_suspcount + 1) {
964 thread_lock(p->p_singlethread);
965 wakeup_swapper = thread_unsuspend_one(
966 p->p_singlethread, p, false);
967 thread_unlock(p->p_singlethread);
975 * When a thread suspends, it just
976 * gets taken off all queues.
978 thread_suspend_one(td);
979 if (return_instead == 0) {
980 p->p_boundary_count++;
981 td->td_flags |= TDF_BOUNDARY;
984 mi_switch(SW_INVOL | SWT_SUSPEND, NULL);
992 thread_suspend_switch(struct thread *td, struct proc *p)
995 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
996 PROC_LOCK_ASSERT(p, MA_OWNED);
997 PROC_SLOCK_ASSERT(p, MA_OWNED);
999 * We implement thread_suspend_one in stages here to avoid
1000 * dropping the proc lock while the thread lock is owned.
1002 if (p == td->td_proc) {
1008 td->td_flags &= ~TDF_NEEDSUSPCHK;
1009 TD_SET_SUSPENDED(td);
1013 mi_switch(SW_VOL | SWT_SUSPEND, NULL);
1021 thread_suspend_one(struct thread *td)
1026 PROC_SLOCK_ASSERT(p, MA_OWNED);
1027 THREAD_LOCK_ASSERT(td, MA_OWNED);
1028 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
1030 td->td_flags &= ~TDF_NEEDSUSPCHK;
1031 TD_SET_SUSPENDED(td);
1036 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary)
1039 THREAD_LOCK_ASSERT(td, MA_OWNED);
1040 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
1041 TD_CLR_SUSPENDED(td);
1042 td->td_flags &= ~TDF_ALLPROCSUSP;
1043 if (td->td_proc == p) {
1044 PROC_SLOCK_ASSERT(p, MA_OWNED);
1046 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) {
1047 td->td_flags &= ~TDF_BOUNDARY;
1048 p->p_boundary_count--;
1051 return (setrunnable(td));
1055 * Allow all threads blocked by single threading to continue running.
1058 thread_unsuspend(struct proc *p)
1063 PROC_LOCK_ASSERT(p, MA_OWNED);
1064 PROC_SLOCK_ASSERT(p, MA_OWNED);
1066 if (!P_SHOULDSTOP(p)) {
1067 FOREACH_THREAD_IN_PROC(p, td) {
1069 if (TD_IS_SUSPENDED(td)) {
1070 wakeup_swapper |= thread_unsuspend_one(td, p,
1075 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
1076 p->p_numthreads == p->p_suspcount) {
1078 * Stopping everything also did the job for the single
1079 * threading request. Now we've downgraded to single-threaded,
1082 if (p->p_singlethread->td_proc == p) {
1083 thread_lock(p->p_singlethread);
1084 wakeup_swapper = thread_unsuspend_one(
1085 p->p_singlethread, p, false);
1086 thread_unlock(p->p_singlethread);
1094 * End the single threading mode..
1097 thread_single_end(struct proc *p, int mode)
1102 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
1103 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
1104 ("invalid mode %d", mode));
1105 PROC_LOCK_ASSERT(p, MA_OWNED);
1106 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) ||
1107 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0),
1108 ("mode %d does not match P_TOTAL_STOP", mode));
1109 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread,
1110 ("thread_single_end from other thread %p %p",
1111 curthread, p->p_singlethread));
1112 KASSERT(mode != SINGLE_BOUNDARY ||
1113 (p->p_flag & P_SINGLE_BOUNDARY) != 0,
1114 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag));
1115 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY |
1118 p->p_singlethread = NULL;
1121 * If there are other threads they may now run,
1122 * unless of course there is a blanket 'stop order'
1123 * on the process. The single threader must be allowed
1124 * to continue however as this is a bad place to stop.
1126 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) {
1127 FOREACH_THREAD_IN_PROC(p, td) {
1129 if (TD_IS_SUSPENDED(td)) {
1130 wakeup_swapper |= thread_unsuspend_one(td, p,
1131 mode == SINGLE_BOUNDARY);
1136 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0,
1137 ("inconsistent boundary count %d", p->p_boundary_count));
1144 thread_find(struct proc *p, lwpid_t tid)
1148 PROC_LOCK_ASSERT(p, MA_OWNED);
1149 FOREACH_THREAD_IN_PROC(p, td) {
1150 if (td->td_tid == tid)
1156 /* Locate a thread by number; return with proc lock held. */
1158 tdfind(lwpid_t tid, pid_t pid)
1160 #define RUN_THRESH 16
1164 rw_rlock(&tidhash_lock);
1165 LIST_FOREACH(td, TIDHASH(tid), td_hash) {
1166 if (td->td_tid == tid) {
1167 if (pid != -1 && td->td_proc->p_pid != pid) {
1171 PROC_LOCK(td->td_proc);
1172 if (td->td_proc->p_state == PRS_NEW) {
1173 PROC_UNLOCK(td->td_proc);
1177 if (run > RUN_THRESH) {
1178 if (rw_try_upgrade(&tidhash_lock)) {
1179 LIST_REMOVE(td, td_hash);
1180 LIST_INSERT_HEAD(TIDHASH(td->td_tid),
1182 rw_wunlock(&tidhash_lock);
1190 rw_runlock(&tidhash_lock);
1195 tidhash_add(struct thread *td)
1197 rw_wlock(&tidhash_lock);
1198 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
1199 rw_wunlock(&tidhash_lock);
1203 tidhash_remove(struct thread *td)
1205 rw_wlock(&tidhash_lock);
1206 LIST_REMOVE(td, td_hash);
1207 rw_wunlock(&tidhash_lock);