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/sysent.h>
49 #include <sys/turnstile.h>
51 #include <sys/rwlock.h>
53 #include <sys/cpuset.h>
55 #include <sys/pmckern.h>
58 #include <security/audit/audit.h>
61 #include <vm/vm_extern.h>
63 #include <sys/eventhandler.h>
65 SDT_PROVIDER_DECLARE(proc);
66 SDT_PROBE_DEFINE(proc, , , lwp__exit);
69 * thread related storage.
71 static uma_zone_t thread_zone;
73 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads);
74 static struct mtx zombie_lock;
75 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN);
77 static void thread_zombie(struct thread *);
78 static int thread_unsuspend_one(struct thread *td, struct proc *p,
81 #define TID_BUFFER_SIZE 1024
84 static struct unrhdr *tid_unrhdr;
85 static lwpid_t tid_buffer[TID_BUFFER_SIZE];
86 static int tid_head, tid_tail;
87 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash");
89 struct tidhashhead *tidhashtbl;
91 struct rwlock tidhash_lock;
98 tid = alloc_unr(tid_unrhdr);
102 if (tid_head == tid_tail) {
103 mtx_unlock(&tid_lock);
106 tid = tid_buffer[tid_head];
107 tid_head = (tid_head + 1) % TID_BUFFER_SIZE;
108 mtx_unlock(&tid_lock);
113 tid_free(lwpid_t tid)
115 lwpid_t tmp_tid = -1;
118 if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) {
119 tmp_tid = tid_buffer[tid_head];
120 tid_head = (tid_head + 1) % TID_BUFFER_SIZE;
122 tid_buffer[tid_tail] = tid;
123 tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE;
124 mtx_unlock(&tid_lock);
126 free_unr(tid_unrhdr, tmp_tid);
130 * Prepare a thread for use.
133 thread_ctor(void *mem, int size, void *arg, int flags)
137 td = (struct thread *)mem;
138 td->td_state = TDS_INACTIVE;
139 td->td_oncpu = NOCPU;
141 td->td_tid = tid_alloc();
144 * Note that td_critnest begins life as 1 because the thread is not
145 * running and is thereby implicitly waiting to be on the receiving
146 * end of a context switch.
149 td->td_lend_user_pri = PRI_MAX;
150 EVENTHANDLER_INVOKE(thread_ctor, td);
152 audit_thread_alloc(td);
154 umtx_thread_alloc(td);
159 * Reclaim a thread after use.
162 thread_dtor(void *mem, int size, void *arg)
166 td = (struct thread *)mem;
169 /* Verify that this thread is in a safe state to free. */
170 switch (td->td_state) {
176 * We must never unlink a thread that is in one of
177 * these states, because it is currently active.
179 panic("bad state for thread unlinking");
184 panic("bad thread state");
189 audit_thread_free(td);
191 /* Free all OSD associated to this thread. */
194 EVENTHANDLER_INVOKE(thread_dtor, td);
195 tid_free(td->td_tid);
199 * Initialize type-stable parts of a thread (when newly created).
202 thread_init(void *mem, int size, int flags)
206 td = (struct thread *)mem;
208 td->td_sleepqueue = sleepq_alloc();
209 td->td_turnstile = turnstile_alloc();
211 EVENTHANDLER_INVOKE(thread_init, td);
212 td->td_sched = (struct td_sched *)&td[1];
213 umtx_thread_init(td);
220 * Tear down type-stable parts of a thread (just before being discarded).
223 thread_fini(void *mem, int size)
227 td = (struct thread *)mem;
228 EVENTHANDLER_INVOKE(thread_fini, td);
229 rlqentry_free(td->td_rlqe);
230 turnstile_free(td->td_turnstile);
231 sleepq_free(td->td_sleepqueue);
232 umtx_thread_fini(td);
237 * For a newly created process,
238 * link up all the structures and its initial threads etc.
240 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc.
241 * proc_dtor() (should go away)
245 proc_linkup0(struct proc *p, struct thread *td)
247 TAILQ_INIT(&p->p_threads); /* all threads in proc */
252 proc_linkup(struct proc *p, struct thread *td)
255 sigqueue_init(&p->p_sigqueue, p);
256 p->p_ksi = ksiginfo_alloc(1);
257 if (p->p_ksi != NULL) {
258 /* XXX p_ksi may be null if ksiginfo zone is not ready */
259 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS;
261 LIST_INIT(&p->p_mqnotifier);
267 * Initialize global thread allocation resources.
273 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
276 * pid_max cannot be greater than PID_MAX.
277 * leave one number for thread0.
279 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock);
281 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
282 thread_ctor, thread_dtor, thread_init, thread_fini,
284 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash);
285 rw_init(&tidhash_lock, "tidhash");
289 * Place an unused thread on the zombie list.
290 * Use the slpq as that must be unused by now.
293 thread_zombie(struct thread *td)
295 mtx_lock_spin(&zombie_lock);
296 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq);
297 mtx_unlock_spin(&zombie_lock);
301 * Release a thread that has exited after cpu_throw().
304 thread_stash(struct thread *td)
306 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1);
311 * Reap zombie resources.
316 struct thread *td_first, *td_next;
319 * Don't even bother to lock if none at this instant,
320 * we really don't care about the next instant..
322 if (!TAILQ_EMPTY(&zombie_threads)) {
323 mtx_lock_spin(&zombie_lock);
324 td_first = TAILQ_FIRST(&zombie_threads);
326 TAILQ_INIT(&zombie_threads);
327 mtx_unlock_spin(&zombie_lock);
329 td_next = TAILQ_NEXT(td_first, td_slpq);
330 thread_cow_free(td_first);
331 thread_free(td_first);
341 thread_alloc(int pages)
345 thread_reap(); /* check if any zombies to get */
347 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK);
348 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
349 if (!vm_thread_new(td, pages)) {
350 uma_zfree(thread_zone, td);
353 cpu_thread_alloc(td);
358 thread_alloc_stack(struct thread *td, int pages)
361 KASSERT(td->td_kstack == 0,
362 ("thread_alloc_stack called on a thread with kstack"));
363 if (!vm_thread_new(td, pages))
365 cpu_thread_alloc(td);
370 * Deallocate a thread.
373 thread_free(struct thread *td)
376 lock_profile_thread_exit(td);
378 cpuset_rel(td->td_cpuset);
379 td->td_cpuset = NULL;
381 if (td->td_kstack != 0)
382 vm_thread_dispose(td);
383 uma_zfree(thread_zone, td);
387 thread_cow_get_proc(struct thread *newtd, struct proc *p)
390 PROC_LOCK_ASSERT(p, MA_OWNED);
391 newtd->td_ucred = crhold(p->p_ucred);
392 newtd->td_limit = lim_hold(p->p_limit);
393 newtd->td_cowgen = p->p_cowgen;
397 thread_cow_get(struct thread *newtd, struct thread *td)
400 newtd->td_ucred = crhold(td->td_ucred);
401 newtd->td_limit = lim_hold(td->td_limit);
402 newtd->td_cowgen = td->td_cowgen;
406 thread_cow_free(struct thread *td)
410 crfree(td->td_ucred);
412 lim_free(td->td_limit);
416 thread_cow_update(struct thread *td)
422 if (td->td_ucred != p->p_ucred)
423 cred_update_thread(td);
424 if (td->td_limit != p->p_limit)
425 lim_update_thread(td);
426 td->td_cowgen = p->p_cowgen;
431 * Discard the current thread and exit from its context.
432 * Always called with scheduler locked.
434 * Because we can't free a thread while we're operating under its context,
435 * push the current thread into our CPU's deadthread holder. This means
436 * we needn't worry about someone else grabbing our context before we
442 uint64_t runtime, new_switchtime;
451 PROC_SLOCK_ASSERT(p, MA_OWNED);
452 mtx_assert(&Giant, MA_NOTOWNED);
454 PROC_LOCK_ASSERT(p, MA_OWNED);
455 KASSERT(p != NULL, ("thread exiting without a process"));
456 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
457 (long)p->p_pid, td->td_name);
458 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
461 AUDIT_SYSCALL_EXIT(0, td);
464 * drop FPU & debug register state storage, or any other
465 * architecture specific resources that
466 * would not be on a new untouched process.
468 cpu_thread_exit(td); /* XXXSMP */
471 * The last thread is left attached to the process
472 * So that the whole bundle gets recycled. Skip
473 * all this stuff if we never had threads.
474 * EXIT clears all sign of other threads when
475 * it goes to single threading, so the last thread always
476 * takes the short path.
478 if (p->p_flag & P_HADTHREADS) {
479 if (p->p_numthreads > 1) {
480 atomic_add_int(&td->td_proc->p_exitthreads, 1);
482 td2 = FIRST_THREAD_IN_PROC(p);
483 sched_exit_thread(td2, td);
486 * The test below is NOT true if we are the
487 * sole exiting thread. P_STOPPED_SINGLE is unset
488 * in exit1() after it is the only survivor.
490 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
491 if (p->p_numthreads == p->p_suspcount) {
492 thread_lock(p->p_singlethread);
493 wakeup_swapper = thread_unsuspend_one(
494 p->p_singlethread, p, false);
495 thread_unlock(p->p_singlethread);
501 PCPU_SET(deadthread, td);
504 * The last thread is exiting.. but not through exit()
506 panic ("thread_exit: Last thread exiting on its own");
511 * If this thread is part of a process that is being tracked by hwpmc(4),
512 * inform the module of the thread's impending exit.
514 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
515 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
522 /* Do the same timestamp bookkeeping that mi_switch() would do. */
523 new_switchtime = cpu_ticks();
524 runtime = new_switchtime - PCPU_GET(switchtime);
525 td->td_runtime += runtime;
526 td->td_incruntime += runtime;
527 PCPU_SET(switchtime, new_switchtime);
528 PCPU_SET(switchticks, ticks);
529 PCPU_INC(cnt.v_swtch);
531 /* Save our resource usage in our process. */
532 td->td_ru.ru_nvcsw++;
534 rucollect(&p->p_ru, &td->td_ru);
537 td->td_state = TDS_INACTIVE;
539 witness_thread_exit(td);
541 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
543 panic("I'm a teapot!");
548 * Do any thread specific cleanups that may be needed in wait()
549 * called with Giant, proc and schedlock not held.
552 thread_wait(struct proc *p)
556 mtx_assert(&Giant, MA_NOTOWNED);
557 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()"));
558 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking"));
559 td = FIRST_THREAD_IN_PROC(p);
560 /* Lock the last thread so we spin until it exits cpu_throw(). */
563 lock_profile_thread_exit(td);
564 cpuset_rel(td->td_cpuset);
565 td->td_cpuset = NULL;
566 cpu_thread_clean(td);
568 thread_reap(); /* check for zombie threads etc. */
572 * Link a thread to a process.
573 * set up anything that needs to be initialized for it to
574 * be used by the process.
577 thread_link(struct thread *td, struct proc *p)
581 * XXX This can't be enabled because it's called for proc0 before
582 * its lock has been created.
583 * PROC_LOCK_ASSERT(p, MA_OWNED);
585 td->td_state = TDS_INACTIVE;
587 td->td_flags = TDF_INMEM;
589 LIST_INIT(&td->td_contested);
590 LIST_INIT(&td->td_lprof[0]);
591 LIST_INIT(&td->td_lprof[1]);
592 sigqueue_init(&td->td_sigqueue, p);
593 callout_init(&td->td_slpcallout, 1);
594 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist);
603 thread_unlink(struct thread *td)
605 struct proc *p = td->td_proc;
607 PROC_LOCK_ASSERT(p, MA_OWNED);
608 TAILQ_REMOVE(&p->p_threads, td, td_plist);
610 /* could clear a few other things here */
611 /* Must NOT clear links to proc! */
615 calc_remaining(struct proc *p, int mode)
619 PROC_LOCK_ASSERT(p, MA_OWNED);
620 PROC_SLOCK_ASSERT(p, MA_OWNED);
621 if (mode == SINGLE_EXIT)
622 remaining = p->p_numthreads;
623 else if (mode == SINGLE_BOUNDARY)
624 remaining = p->p_numthreads - p->p_boundary_count;
625 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC)
626 remaining = p->p_numthreads - p->p_suspcount;
628 panic("calc_remaining: wrong mode %d", mode);
633 remain_for_mode(int mode)
636 return (mode == SINGLE_ALLPROC ? 0 : 1);
640 weed_inhib(int mode, struct thread *td2, struct proc *p)
644 PROC_LOCK_ASSERT(p, MA_OWNED);
645 PROC_SLOCK_ASSERT(p, MA_OWNED);
646 THREAD_LOCK_ASSERT(td2, MA_OWNED);
651 if (TD_IS_SUSPENDED(td2))
652 wakeup_swapper |= thread_unsuspend_one(td2, p, true);
653 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0)
654 wakeup_swapper |= sleepq_abort(td2, EINTR);
656 case SINGLE_BOUNDARY:
657 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0)
658 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
659 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0)
660 wakeup_swapper |= sleepq_abort(td2, ERESTART);
663 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0)
664 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
665 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0)
666 wakeup_swapper |= sleepq_abort(td2, ERESTART);
670 * ALLPROC suspend tries to avoid spurious EINTR for
671 * threads sleeping interruptable, by suspending the
672 * thread directly, similarly to sig_suspend_threads().
673 * Since such sleep is not performed at the user
674 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP
675 * is used to avoid immediate un-suspend.
677 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY |
678 TDF_ALLPROCSUSP)) == 0)
679 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
680 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) {
681 if ((td2->td_flags & TDF_SBDRY) == 0) {
682 thread_suspend_one(td2);
683 td2->td_flags |= TDF_ALLPROCSUSP;
685 wakeup_swapper |= sleepq_abort(td2, ERESTART);
690 return (wakeup_swapper);
694 * Enforce single-threading.
696 * Returns 1 if the caller must abort (another thread is waiting to
697 * exit the process or similar). Process is locked!
698 * Returns 0 when you are successfully the only thread running.
699 * A process has successfully single threaded in the suspend mode when
700 * There are no threads in user mode. Threads in the kernel must be
701 * allowed to continue until they get to the user boundary. They may even
702 * copy out their return values and data before suspending. They may however be
703 * accelerated in reaching the user boundary as we will wake up
704 * any sleeping threads that are interruptable. (PCATCH).
707 thread_single(struct proc *p, int mode)
711 int remaining, wakeup_swapper;
714 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
715 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
716 ("invalid mode %d", mode));
718 * If allowing non-ALLPROC singlethreading for non-curproc
719 * callers, calc_remaining() and remain_for_mode() should be
720 * adjusted to also account for td->td_proc != p. For now
721 * this is not implemented because it is not used.
723 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) ||
724 (mode != SINGLE_ALLPROC && td->td_proc == p),
725 ("mode %d proc %p curproc %p", mode, p, td->td_proc));
726 mtx_assert(&Giant, MA_NOTOWNED);
727 PROC_LOCK_ASSERT(p, MA_OWNED);
729 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC)
732 /* Is someone already single threading? */
733 if (p->p_singlethread != NULL && p->p_singlethread != td)
736 if (mode == SINGLE_EXIT) {
737 p->p_flag |= P_SINGLE_EXIT;
738 p->p_flag &= ~P_SINGLE_BOUNDARY;
740 p->p_flag &= ~P_SINGLE_EXIT;
741 if (mode == SINGLE_BOUNDARY)
742 p->p_flag |= P_SINGLE_BOUNDARY;
744 p->p_flag &= ~P_SINGLE_BOUNDARY;
746 if (mode == SINGLE_ALLPROC)
747 p->p_flag |= P_TOTAL_STOP;
748 p->p_flag |= P_STOPPED_SINGLE;
750 p->p_singlethread = td;
751 remaining = calc_remaining(p, mode);
752 while (remaining != remain_for_mode(mode)) {
753 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE)
756 FOREACH_THREAD_IN_PROC(p, td2) {
760 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK;
761 if (TD_IS_INHIBITED(td2)) {
762 wakeup_swapper |= weed_inhib(mode, td2, p);
764 } else if (TD_IS_RUNNING(td2) && td != td2) {
772 remaining = calc_remaining(p, mode);
775 * Maybe we suspended some threads.. was it enough?
777 if (remaining == remain_for_mode(mode))
782 * Wake us up when everyone else has suspended.
783 * In the mean time we suspend as well.
785 thread_suspend_switch(td, p);
786 remaining = calc_remaining(p, mode);
788 if (mode == SINGLE_EXIT) {
790 * Convert the process to an unthreaded process. The
791 * SINGLE_EXIT is called by exit1() or execve(), in
792 * both cases other threads must be retired.
794 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads"));
795 p->p_singlethread = NULL;
796 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS);
799 * Wait for any remaining threads to exit cpu_throw().
801 while (p->p_exitthreads != 0) {
804 sched_relinquish(td);
808 } else if (mode == SINGLE_BOUNDARY) {
810 * Wait until all suspended threads are removed from
811 * the processors. The thread_suspend_check()
812 * increments p_boundary_count while it is still
813 * running, which makes it possible for the execve()
814 * to destroy vmspace while our other threads are
815 * still using the address space.
817 * We lock the thread, which is only allowed to
818 * succeed after context switch code finished using
821 FOREACH_THREAD_IN_PROC(p, td2) {
825 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0,
826 ("td %p not on boundary", td2));
827 KASSERT(TD_IS_SUSPENDED(td2),
828 ("td %p is not suspended", td2));
837 thread_suspend_check_needed(void)
844 PROC_LOCK_ASSERT(p, MA_OWNED);
845 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 &&
846 (td->td_dbgflags & TDB_SUSPEND) != 0));
850 * Called in from locations that can safely check to see
851 * whether we have to suspend or at least throttle for a
852 * single-thread event (e.g. fork).
854 * Such locations include userret().
855 * If the "return_instead" argument is non zero, the thread must be able to
856 * accept 0 (caller may continue), or 1 (caller must abort) as a result.
858 * The 'return_instead' argument tells the function if it may do a
859 * thread_exit() or suspend, or whether the caller must abort and back
862 * If the thread that set the single_threading request has set the
863 * P_SINGLE_EXIT bit in the process flags then this call will never return
864 * if 'return_instead' is false, but will exit.
866 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0
867 *---------------+--------------------+---------------------
868 * 0 | returns 0 | returns 0 or 1
869 * | when ST ends | immediately
870 *---------------+--------------------+---------------------
871 * 1 | thread exits | returns 1
873 * 0 = thread_exit() or suspension ok,
874 * other = return error instead of stopping the thread.
876 * While a full suspension is under effect, even a single threading
877 * thread would be suspended if it made this call (but it shouldn't).
878 * This call should only be made from places where
879 * thread_exit() would be safe as that may be the outcome unless
880 * return_instead is set.
883 thread_suspend_check(int return_instead)
891 mtx_assert(&Giant, MA_NOTOWNED);
892 PROC_LOCK_ASSERT(p, MA_OWNED);
893 while (thread_suspend_check_needed()) {
894 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
895 KASSERT(p->p_singlethread != NULL,
896 ("singlethread not set"));
898 * The only suspension in action is a
899 * single-threading. Single threader need not stop.
900 * XXX Should be safe to access unlocked
901 * as it can only be set to be true by us.
903 if (p->p_singlethread == td)
904 return (0); /* Exempt from stopping. */
906 if ((p->p_flag & P_SINGLE_EXIT) && return_instead)
909 /* Should we goto user boundary if we didn't come from there? */
910 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
911 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
915 * Ignore suspend requests if they are deferred.
917 if ((td->td_flags & TDF_SBDRY) != 0) {
918 KASSERT(return_instead,
919 ("TDF_SBDRY set for unsafe thread_suspend_check"));
924 * If the process is waiting for us to exit,
925 * this thread should just suicide.
926 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
928 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
933 * Allow Linux emulation layer to do some work
934 * before thread suicide.
936 if (__predict_false(p->p_sysent->sv_thread_detach != NULL))
937 (p->p_sysent->sv_thread_detach)(td);
941 umtx_thread_exit(td);
949 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
950 if (p->p_numthreads == p->p_suspcount + 1) {
951 thread_lock(p->p_singlethread);
952 wakeup_swapper = thread_unsuspend_one(
953 p->p_singlethread, p, false);
954 thread_unlock(p->p_singlethread);
962 * When a thread suspends, it just
963 * gets taken off all queues.
965 thread_suspend_one(td);
966 if (return_instead == 0) {
967 p->p_boundary_count++;
968 td->td_flags |= TDF_BOUNDARY;
971 mi_switch(SW_INVOL | SWT_SUSPEND, NULL);
979 thread_suspend_switch(struct thread *td, struct proc *p)
982 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
983 PROC_LOCK_ASSERT(p, MA_OWNED);
984 PROC_SLOCK_ASSERT(p, MA_OWNED);
986 * We implement thread_suspend_one in stages here to avoid
987 * dropping the proc lock while the thread lock is owned.
989 if (p == td->td_proc) {
995 td->td_flags &= ~TDF_NEEDSUSPCHK;
996 TD_SET_SUSPENDED(td);
1000 mi_switch(SW_VOL | SWT_SUSPEND, NULL);
1008 thread_suspend_one(struct thread *td)
1013 PROC_SLOCK_ASSERT(p, MA_OWNED);
1014 THREAD_LOCK_ASSERT(td, MA_OWNED);
1015 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
1017 td->td_flags &= ~TDF_NEEDSUSPCHK;
1018 TD_SET_SUSPENDED(td);
1023 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary)
1026 THREAD_LOCK_ASSERT(td, MA_OWNED);
1027 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
1028 TD_CLR_SUSPENDED(td);
1029 td->td_flags &= ~TDF_ALLPROCSUSP;
1030 if (td->td_proc == p) {
1031 PROC_SLOCK_ASSERT(p, MA_OWNED);
1033 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) {
1034 td->td_flags &= ~TDF_BOUNDARY;
1035 p->p_boundary_count--;
1038 return (setrunnable(td));
1042 * Allow all threads blocked by single threading to continue running.
1045 thread_unsuspend(struct proc *p)
1050 PROC_LOCK_ASSERT(p, MA_OWNED);
1051 PROC_SLOCK_ASSERT(p, MA_OWNED);
1053 if (!P_SHOULDSTOP(p)) {
1054 FOREACH_THREAD_IN_PROC(p, td) {
1056 if (TD_IS_SUSPENDED(td)) {
1057 wakeup_swapper |= thread_unsuspend_one(td, p,
1062 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
1063 p->p_numthreads == p->p_suspcount) {
1065 * Stopping everything also did the job for the single
1066 * threading request. Now we've downgraded to single-threaded,
1069 if (p->p_singlethread->td_proc == p) {
1070 thread_lock(p->p_singlethread);
1071 wakeup_swapper = thread_unsuspend_one(
1072 p->p_singlethread, p, false);
1073 thread_unlock(p->p_singlethread);
1081 * End the single threading mode..
1084 thread_single_end(struct proc *p, int mode)
1089 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
1090 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
1091 ("invalid mode %d", mode));
1092 PROC_LOCK_ASSERT(p, MA_OWNED);
1093 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) ||
1094 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0),
1095 ("mode %d does not match P_TOTAL_STOP", mode));
1096 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread,
1097 ("thread_single_end from other thread %p %p",
1098 curthread, p->p_singlethread));
1099 KASSERT(mode != SINGLE_BOUNDARY ||
1100 (p->p_flag & P_SINGLE_BOUNDARY) != 0,
1101 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag));
1102 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY |
1105 p->p_singlethread = NULL;
1108 * If there are other threads they may now run,
1109 * unless of course there is a blanket 'stop order'
1110 * on the process. The single threader must be allowed
1111 * to continue however as this is a bad place to stop.
1113 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) {
1114 FOREACH_THREAD_IN_PROC(p, td) {
1116 if (TD_IS_SUSPENDED(td)) {
1117 wakeup_swapper |= thread_unsuspend_one(td, p,
1118 mode == SINGLE_BOUNDARY);
1123 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0,
1124 ("inconsistent boundary count %d", p->p_boundary_count));
1131 thread_find(struct proc *p, lwpid_t tid)
1135 PROC_LOCK_ASSERT(p, MA_OWNED);
1136 FOREACH_THREAD_IN_PROC(p, td) {
1137 if (td->td_tid == tid)
1143 /* Locate a thread by number; return with proc lock held. */
1145 tdfind(lwpid_t tid, pid_t pid)
1147 #define RUN_THRESH 16
1151 rw_rlock(&tidhash_lock);
1152 LIST_FOREACH(td, TIDHASH(tid), td_hash) {
1153 if (td->td_tid == tid) {
1154 if (pid != -1 && td->td_proc->p_pid != pid) {
1158 PROC_LOCK(td->td_proc);
1159 if (td->td_proc->p_state == PRS_NEW) {
1160 PROC_UNLOCK(td->td_proc);
1164 if (run > RUN_THRESH) {
1165 if (rw_try_upgrade(&tidhash_lock)) {
1166 LIST_REMOVE(td, td_hash);
1167 LIST_INSERT_HEAD(TIDHASH(td->td_tid),
1169 rw_wunlock(&tidhash_lock);
1177 rw_runlock(&tidhash_lock);
1182 tidhash_add(struct thread *td)
1184 rw_wlock(&tidhash_lock);
1185 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
1186 rw_wunlock(&tidhash_lock);
1190 tidhash_remove(struct thread *td)
1192 rw_wlock(&tidhash_lock);
1193 LIST_REMOVE(td, td_hash);
1194 rw_wunlock(&tidhash_lock);