2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (C) 2001 Julian Elischer <julian@freebsd.org>.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice(s), this list of conditions and the following disclaimer as
12 * the first lines of this file unmodified other than the possible
13 * addition of one or more copyright notices.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice(s), this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
19 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
22 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
24 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
25 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
31 #include "opt_witness.h"
32 #include "opt_hwpmc_hooks.h"
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/kernel.h>
41 #include <sys/mutex.h>
43 #include <sys/epoch.h>
44 #include <sys/rangelock.h>
45 #include <sys/resourcevar.h>
48 #include <sys/sched.h>
49 #include <sys/sleepqueue.h>
50 #include <sys/selinfo.h>
51 #include <sys/syscallsubr.h>
52 #include <sys/sysent.h>
53 #include <sys/turnstile.h>
55 #include <sys/rwlock.h>
57 #include <sys/vmmeter.h>
58 #include <sys/cpuset.h>
60 #include <sys/pmckern.h>
63 #include <security/audit/audit.h>
66 #include <vm/vm_extern.h>
68 #include <sys/eventhandler.h>
71 * Asserts below verify the stability of struct thread and struct proc
72 * layout, as exposed by KBI to modules. On head, the KBI is allowed
73 * to drift, change to the structures must be accompanied by the
76 * On the stable branches after KBI freeze, conditions must not be
77 * violated. Typically new fields are moved to the end of the
81 _Static_assert(offsetof(struct thread, td_flags) == 0xfc,
82 "struct thread KBI td_flags");
83 _Static_assert(offsetof(struct thread, td_pflags) == 0x104,
84 "struct thread KBI td_pflags");
85 _Static_assert(offsetof(struct thread, td_frame) == 0x4a8,
86 "struct thread KBI td_frame");
87 _Static_assert(offsetof(struct thread, td_emuldata) == 0x6b0,
88 "struct thread KBI td_emuldata");
89 _Static_assert(offsetof(struct proc, p_flag) == 0xb0,
90 "struct proc KBI p_flag");
91 _Static_assert(offsetof(struct proc, p_pid) == 0xbc,
92 "struct proc KBI p_pid");
93 _Static_assert(offsetof(struct proc, p_filemon) == 0x3b8,
94 "struct proc KBI p_filemon");
95 _Static_assert(offsetof(struct proc, p_comm) == 0x3d0,
96 "struct proc KBI p_comm");
97 _Static_assert(offsetof(struct proc, p_emuldata) == 0x4b0,
98 "struct proc KBI p_emuldata");
101 _Static_assert(offsetof(struct thread, td_flags) == 0x98,
102 "struct thread KBI td_flags");
103 _Static_assert(offsetof(struct thread, td_pflags) == 0xa0,
104 "struct thread KBI td_pflags");
105 _Static_assert(offsetof(struct thread, td_frame) == 0x304,
106 "struct thread KBI td_frame");
107 _Static_assert(offsetof(struct thread, td_emuldata) == 0x348,
108 "struct thread KBI td_emuldata");
109 _Static_assert(offsetof(struct proc, p_flag) == 0x68,
110 "struct proc KBI p_flag");
111 _Static_assert(offsetof(struct proc, p_pid) == 0x74,
112 "struct proc KBI p_pid");
113 _Static_assert(offsetof(struct proc, p_filemon) == 0x268,
114 "struct proc KBI p_filemon");
115 _Static_assert(offsetof(struct proc, p_comm) == 0x27c,
116 "struct proc KBI p_comm");
117 _Static_assert(offsetof(struct proc, p_emuldata) == 0x308,
118 "struct proc KBI p_emuldata");
121 SDT_PROVIDER_DECLARE(proc);
122 SDT_PROBE_DEFINE(proc, , , lwp__exit);
125 * thread related storage.
127 static uma_zone_t thread_zone;
129 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads);
130 static struct mtx zombie_lock;
131 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN);
133 static void thread_zombie(struct thread *);
134 static int thread_unsuspend_one(struct thread *td, struct proc *p,
137 #define TID_BUFFER_SIZE 1024
140 static struct unrhdr *tid_unrhdr;
141 static lwpid_t tid_buffer[TID_BUFFER_SIZE];
142 static int tid_head, tid_tail;
143 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash");
145 struct tidhashhead *tidhashtbl;
147 struct rwlock tidhash_lock;
149 EVENTHANDLER_LIST_DEFINE(thread_ctor);
150 EVENTHANDLER_LIST_DEFINE(thread_dtor);
151 EVENTHANDLER_LIST_DEFINE(thread_init);
152 EVENTHANDLER_LIST_DEFINE(thread_fini);
159 tid = alloc_unr(tid_unrhdr);
163 if (tid_head == tid_tail) {
164 mtx_unlock(&tid_lock);
167 tid = tid_buffer[tid_head];
168 tid_head = (tid_head + 1) % TID_BUFFER_SIZE;
169 mtx_unlock(&tid_lock);
174 tid_free(lwpid_t tid)
176 lwpid_t tmp_tid = -1;
179 if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) {
180 tmp_tid = tid_buffer[tid_head];
181 tid_head = (tid_head + 1) % TID_BUFFER_SIZE;
183 tid_buffer[tid_tail] = tid;
184 tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE;
185 mtx_unlock(&tid_lock);
187 free_unr(tid_unrhdr, tmp_tid);
191 * Prepare a thread for use.
194 thread_ctor(void *mem, int size, void *arg, int flags)
198 td = (struct thread *)mem;
199 td->td_state = TDS_INACTIVE;
200 td->td_lastcpu = td->td_oncpu = NOCPU;
202 td->td_tid = tid_alloc();
205 * Note that td_critnest begins life as 1 because the thread is not
206 * running and is thereby implicitly waiting to be on the receiving
207 * end of a context switch.
210 td->td_lend_user_pri = PRI_MAX;
211 EVENTHANDLER_DIRECT_INVOKE(thread_ctor, td);
213 audit_thread_alloc(td);
215 umtx_thread_alloc(td);
220 * Reclaim a thread after use.
223 thread_dtor(void *mem, int size, void *arg)
227 td = (struct thread *)mem;
230 /* Verify that this thread is in a safe state to free. */
231 switch (td->td_state) {
237 * We must never unlink a thread that is in one of
238 * these states, because it is currently active.
240 panic("bad state for thread unlinking");
245 panic("bad thread state");
250 audit_thread_free(td);
252 /* Free all OSD associated to this thread. */
254 td_softdep_cleanup(td);
255 MPASS(td->td_su == NULL);
257 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, td);
258 tid_free(td->td_tid);
262 * Initialize type-stable parts of a thread (when newly created).
265 thread_init(void *mem, int size, int flags)
269 td = (struct thread *)mem;
271 td->td_sleepqueue = sleepq_alloc();
272 td->td_turnstile = turnstile_alloc();
274 EVENTHANDLER_DIRECT_INVOKE(thread_init, td);
275 umtx_thread_init(td);
282 * Tear down type-stable parts of a thread (just before being discarded).
285 thread_fini(void *mem, int size)
289 td = (struct thread *)mem;
290 EVENTHANDLER_DIRECT_INVOKE(thread_fini, td);
291 rlqentry_free(td->td_rlqe);
292 turnstile_free(td->td_turnstile);
293 sleepq_free(td->td_sleepqueue);
294 umtx_thread_fini(td);
299 * For a newly created process,
300 * link up all the structures and its initial threads etc.
302 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc.
303 * proc_dtor() (should go away)
307 proc_linkup0(struct proc *p, struct thread *td)
309 TAILQ_INIT(&p->p_threads); /* all threads in proc */
314 proc_linkup(struct proc *p, struct thread *td)
317 sigqueue_init(&p->p_sigqueue, p);
318 p->p_ksi = ksiginfo_alloc(1);
319 if (p->p_ksi != NULL) {
320 /* XXX p_ksi may be null if ksiginfo zone is not ready */
321 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS;
323 LIST_INIT(&p->p_mqnotifier);
329 * Initialize global thread allocation resources.
336 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
339 * pid_max cannot be greater than PID_MAX.
340 * leave one number for thread0.
342 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock);
344 flags = UMA_ZONE_NOFREE;
347 * Force thread structures to be allocated from the direct map.
348 * Otherwise, superpage promotions and demotions may temporarily
349 * invalidate thread structure mappings. For most dynamically allocated
350 * structures this is not a problem, but translation faults cannot be
351 * handled without accessing curthread.
353 flags |= UMA_ZONE_CONTIG;
355 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
356 thread_ctor, thread_dtor, thread_init, thread_fini,
358 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash);
359 rw_init(&tidhash_lock, "tidhash");
363 * Place an unused thread on the zombie list.
364 * Use the slpq as that must be unused by now.
367 thread_zombie(struct thread *td)
369 mtx_lock_spin(&zombie_lock);
370 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq);
371 mtx_unlock_spin(&zombie_lock);
375 * Release a thread that has exited after cpu_throw().
378 thread_stash(struct thread *td)
380 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1);
385 * Reap zombie resources.
390 struct thread *td_first, *td_next;
393 * Don't even bother to lock if none at this instant,
394 * we really don't care about the next instant.
396 if (!TAILQ_EMPTY(&zombie_threads)) {
397 mtx_lock_spin(&zombie_lock);
398 td_first = TAILQ_FIRST(&zombie_threads);
400 TAILQ_INIT(&zombie_threads);
401 mtx_unlock_spin(&zombie_lock);
403 td_next = TAILQ_NEXT(td_first, td_slpq);
404 thread_cow_free(td_first);
405 thread_free(td_first);
415 thread_alloc(int pages)
419 thread_reap(); /* check if any zombies to get */
421 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK);
422 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
423 if (!vm_thread_new(td, pages)) {
424 uma_zfree(thread_zone, td);
427 cpu_thread_alloc(td);
432 thread_alloc_stack(struct thread *td, int pages)
435 KASSERT(td->td_kstack == 0,
436 ("thread_alloc_stack called on a thread with kstack"));
437 if (!vm_thread_new(td, pages))
439 cpu_thread_alloc(td);
444 * Deallocate a thread.
447 thread_free(struct thread *td)
450 lock_profile_thread_exit(td);
452 cpuset_rel(td->td_cpuset);
453 td->td_cpuset = NULL;
455 if (td->td_kstack != 0)
456 vm_thread_dispose(td);
457 callout_drain(&td->td_slpcallout);
458 uma_zfree(thread_zone, td);
462 thread_cow_get_proc(struct thread *newtd, struct proc *p)
465 PROC_LOCK_ASSERT(p, MA_OWNED);
466 newtd->td_realucred = crcowget(p->p_ucred);
467 newtd->td_ucred = newtd->td_realucred;
468 newtd->td_limit = lim_hold(p->p_limit);
469 newtd->td_cowgen = p->p_cowgen;
473 thread_cow_get(struct thread *newtd, struct thread *td)
476 MPASS(td->td_realucred == td->td_ucred);
477 newtd->td_realucred = crcowget(td->td_realucred);
478 newtd->td_ucred = newtd->td_realucred;
479 newtd->td_limit = lim_hold(td->td_limit);
480 newtd->td_cowgen = td->td_cowgen;
484 thread_cow_free(struct thread *td)
487 if (td->td_realucred != NULL)
489 if (td->td_limit != NULL)
490 lim_free(td->td_limit);
494 thread_cow_update(struct thread *td)
497 struct ucred *oldcred;
498 struct plimit *oldlimit;
503 oldcred = crcowsync();
504 if (td->td_limit != p->p_limit) {
505 oldlimit = td->td_limit;
506 td->td_limit = lim_hold(p->p_limit);
508 td->td_cowgen = p->p_cowgen;
512 if (oldlimit != NULL)
517 * Discard the current thread and exit from its context.
518 * Always called with scheduler locked.
520 * Because we can't free a thread while we're operating under its context,
521 * push the current thread into our CPU's deadthread holder. This means
522 * we needn't worry about someone else grabbing our context before we
528 uint64_t runtime, new_switchtime;
537 PROC_SLOCK_ASSERT(p, MA_OWNED);
538 mtx_assert(&Giant, MA_NOTOWNED);
540 PROC_LOCK_ASSERT(p, MA_OWNED);
541 KASSERT(p != NULL, ("thread exiting without a process"));
542 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
543 (long)p->p_pid, td->td_name);
544 SDT_PROBE0(proc, , , lwp__exit);
545 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
548 * drop FPU & debug register state storage, or any other
549 * architecture specific resources that
550 * would not be on a new untouched process.
555 * The last thread is left attached to the process
556 * So that the whole bundle gets recycled. Skip
557 * all this stuff if we never had threads.
558 * EXIT clears all sign of other threads when
559 * it goes to single threading, so the last thread always
560 * takes the short path.
562 if (p->p_flag & P_HADTHREADS) {
563 if (p->p_numthreads > 1) {
564 atomic_add_int(&td->td_proc->p_exitthreads, 1);
566 td2 = FIRST_THREAD_IN_PROC(p);
567 sched_exit_thread(td2, td);
570 * The test below is NOT true if we are the
571 * sole exiting thread. P_STOPPED_SINGLE is unset
572 * in exit1() after it is the only survivor.
574 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
575 if (p->p_numthreads == p->p_suspcount) {
576 thread_lock(p->p_singlethread);
577 wakeup_swapper = thread_unsuspend_one(
578 p->p_singlethread, p, false);
584 PCPU_SET(deadthread, td);
587 * The last thread is exiting.. but not through exit()
589 panic ("thread_exit: Last thread exiting on its own");
594 * If this thread is part of a process that is being tracked by hwpmc(4),
595 * inform the module of the thread's impending exit.
597 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) {
598 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
599 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT, NULL);
600 } else if (PMC_SYSTEM_SAMPLING_ACTIVE())
601 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL);
608 /* Do the same timestamp bookkeeping that mi_switch() would do. */
609 new_switchtime = cpu_ticks();
610 runtime = new_switchtime - PCPU_GET(switchtime);
611 td->td_runtime += runtime;
612 td->td_incruntime += runtime;
613 PCPU_SET(switchtime, new_switchtime);
614 PCPU_SET(switchticks, ticks);
617 /* Save our resource usage in our process. */
618 td->td_ru.ru_nvcsw++;
619 ruxagg_locked(p, td);
620 rucollect(&p->p_ru, &td->td_ru);
623 td->td_state = TDS_INACTIVE;
625 witness_thread_exit(td);
627 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
629 panic("I'm a teapot!");
634 * Do any thread specific cleanups that may be needed in wait()
635 * called with Giant, proc and schedlock not held.
638 thread_wait(struct proc *p)
642 mtx_assert(&Giant, MA_NOTOWNED);
643 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()"));
644 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking"));
645 td = FIRST_THREAD_IN_PROC(p);
646 /* Lock the last thread so we spin until it exits cpu_throw(). */
649 lock_profile_thread_exit(td);
650 cpuset_rel(td->td_cpuset);
651 td->td_cpuset = NULL;
652 cpu_thread_clean(td);
654 callout_drain(&td->td_slpcallout);
655 thread_reap(); /* check for zombie threads etc. */
659 * Link a thread to a process.
660 * set up anything that needs to be initialized for it to
661 * be used by the process.
664 thread_link(struct thread *td, struct proc *p)
668 * XXX This can't be enabled because it's called for proc0 before
669 * its lock has been created.
670 * PROC_LOCK_ASSERT(p, MA_OWNED);
672 td->td_state = TDS_INACTIVE;
674 td->td_flags = TDF_INMEM;
676 LIST_INIT(&td->td_contested);
677 LIST_INIT(&td->td_lprof[0]);
678 LIST_INIT(&td->td_lprof[1]);
680 SLIST_INIT(&td->td_epochs);
682 sigqueue_init(&td->td_sigqueue, p);
683 callout_init(&td->td_slpcallout, 1);
684 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist);
693 thread_unlink(struct thread *td)
695 struct proc *p = td->td_proc;
697 PROC_LOCK_ASSERT(p, MA_OWNED);
699 MPASS(SLIST_EMPTY(&td->td_epochs));
702 TAILQ_REMOVE(&p->p_threads, td, td_plist);
704 /* could clear a few other things here */
705 /* Must NOT clear links to proc! */
709 calc_remaining(struct proc *p, int mode)
713 PROC_LOCK_ASSERT(p, MA_OWNED);
714 PROC_SLOCK_ASSERT(p, MA_OWNED);
715 if (mode == SINGLE_EXIT)
716 remaining = p->p_numthreads;
717 else if (mode == SINGLE_BOUNDARY)
718 remaining = p->p_numthreads - p->p_boundary_count;
719 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC)
720 remaining = p->p_numthreads - p->p_suspcount;
722 panic("calc_remaining: wrong mode %d", mode);
727 remain_for_mode(int mode)
730 return (mode == SINGLE_ALLPROC ? 0 : 1);
734 weed_inhib(int mode, struct thread *td2, struct proc *p)
738 PROC_LOCK_ASSERT(p, MA_OWNED);
739 PROC_SLOCK_ASSERT(p, MA_OWNED);
740 THREAD_LOCK_ASSERT(td2, MA_OWNED);
745 * Since the thread lock is dropped by the scheduler we have
746 * to retry to check for races.
751 if (TD_IS_SUSPENDED(td2)) {
752 wakeup_swapper |= thread_unsuspend_one(td2, p, true);
756 if (TD_CAN_ABORT(td2)) {
757 wakeup_swapper |= sleepq_abort(td2, EINTR);
758 return (wakeup_swapper);
761 case SINGLE_BOUNDARY:
763 if (TD_IS_SUSPENDED(td2) &&
764 (td2->td_flags & TDF_BOUNDARY) == 0) {
765 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
769 if (TD_CAN_ABORT(td2)) {
770 wakeup_swapper |= sleepq_abort(td2, ERESTART);
771 return (wakeup_swapper);
776 * ALLPROC suspend tries to avoid spurious EINTR for
777 * threads sleeping interruptable, by suspending the
778 * thread directly, similarly to sig_suspend_threads().
779 * Since such sleep is not performed at the user
780 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP
781 * is used to avoid immediate un-suspend.
783 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY |
784 TDF_ALLPROCSUSP)) == 0) {
785 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
789 if (TD_CAN_ABORT(td2)) {
790 if ((td2->td_flags & TDF_SBDRY) == 0) {
791 thread_suspend_one(td2);
792 td2->td_flags |= TDF_ALLPROCSUSP;
794 wakeup_swapper |= sleepq_abort(td2, ERESTART);
795 return (wakeup_swapper);
803 return (wakeup_swapper);
807 * Enforce single-threading.
809 * Returns 1 if the caller must abort (another thread is waiting to
810 * exit the process or similar). Process is locked!
811 * Returns 0 when you are successfully the only thread running.
812 * A process has successfully single threaded in the suspend mode when
813 * There are no threads in user mode. Threads in the kernel must be
814 * allowed to continue until they get to the user boundary. They may even
815 * copy out their return values and data before suspending. They may however be
816 * accelerated in reaching the user boundary as we will wake up
817 * any sleeping threads that are interruptable. (PCATCH).
820 thread_single(struct proc *p, int mode)
824 int remaining, wakeup_swapper;
827 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
828 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
829 ("invalid mode %d", mode));
831 * If allowing non-ALLPROC singlethreading for non-curproc
832 * callers, calc_remaining() and remain_for_mode() should be
833 * adjusted to also account for td->td_proc != p. For now
834 * this is not implemented because it is not used.
836 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) ||
837 (mode != SINGLE_ALLPROC && td->td_proc == p),
838 ("mode %d proc %p curproc %p", mode, p, td->td_proc));
839 mtx_assert(&Giant, MA_NOTOWNED);
840 PROC_LOCK_ASSERT(p, MA_OWNED);
842 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC)
845 /* Is someone already single threading? */
846 if (p->p_singlethread != NULL && p->p_singlethread != td)
849 if (mode == SINGLE_EXIT) {
850 p->p_flag |= P_SINGLE_EXIT;
851 p->p_flag &= ~P_SINGLE_BOUNDARY;
853 p->p_flag &= ~P_SINGLE_EXIT;
854 if (mode == SINGLE_BOUNDARY)
855 p->p_flag |= P_SINGLE_BOUNDARY;
857 p->p_flag &= ~P_SINGLE_BOUNDARY;
859 if (mode == SINGLE_ALLPROC)
860 p->p_flag |= P_TOTAL_STOP;
861 p->p_flag |= P_STOPPED_SINGLE;
863 p->p_singlethread = td;
864 remaining = calc_remaining(p, mode);
865 while (remaining != remain_for_mode(mode)) {
866 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE)
869 FOREACH_THREAD_IN_PROC(p, td2) {
873 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK;
874 if (TD_IS_INHIBITED(td2)) {
875 wakeup_swapper |= weed_inhib(mode, td2, p);
877 } else if (TD_IS_RUNNING(td2) && td != td2) {
886 remaining = calc_remaining(p, mode);
889 * Maybe we suspended some threads.. was it enough?
891 if (remaining == remain_for_mode(mode))
896 * Wake us up when everyone else has suspended.
897 * In the mean time we suspend as well.
899 thread_suspend_switch(td, p);
900 remaining = calc_remaining(p, mode);
902 if (mode == SINGLE_EXIT) {
904 * Convert the process to an unthreaded process. The
905 * SINGLE_EXIT is called by exit1() or execve(), in
906 * both cases other threads must be retired.
908 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads"));
909 p->p_singlethread = NULL;
910 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS);
913 * Wait for any remaining threads to exit cpu_throw().
915 while (p->p_exitthreads != 0) {
918 sched_relinquish(td);
922 } else if (mode == SINGLE_BOUNDARY) {
924 * Wait until all suspended threads are removed from
925 * the processors. The thread_suspend_check()
926 * increments p_boundary_count while it is still
927 * running, which makes it possible for the execve()
928 * to destroy vmspace while our other threads are
929 * still using the address space.
931 * We lock the thread, which is only allowed to
932 * succeed after context switch code finished using
935 FOREACH_THREAD_IN_PROC(p, td2) {
939 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0,
940 ("td %p not on boundary", td2));
941 KASSERT(TD_IS_SUSPENDED(td2),
942 ("td %p is not suspended", td2));
951 thread_suspend_check_needed(void)
958 PROC_LOCK_ASSERT(p, MA_OWNED);
959 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 &&
960 (td->td_dbgflags & TDB_SUSPEND) != 0));
964 * Called in from locations that can safely check to see
965 * whether we have to suspend or at least throttle for a
966 * single-thread event (e.g. fork).
968 * Such locations include userret().
969 * If the "return_instead" argument is non zero, the thread must be able to
970 * accept 0 (caller may continue), or 1 (caller must abort) as a result.
972 * The 'return_instead' argument tells the function if it may do a
973 * thread_exit() or suspend, or whether the caller must abort and back
976 * If the thread that set the single_threading request has set the
977 * P_SINGLE_EXIT bit in the process flags then this call will never return
978 * if 'return_instead' is false, but will exit.
980 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0
981 *---------------+--------------------+---------------------
982 * 0 | returns 0 | returns 0 or 1
983 * | when ST ends | immediately
984 *---------------+--------------------+---------------------
985 * 1 | thread exits | returns 1
987 * 0 = thread_exit() or suspension ok,
988 * other = return error instead of stopping the thread.
990 * While a full suspension is under effect, even a single threading
991 * thread would be suspended if it made this call (but it shouldn't).
992 * This call should only be made from places where
993 * thread_exit() would be safe as that may be the outcome unless
994 * return_instead is set.
997 thread_suspend_check(int return_instead)
1005 mtx_assert(&Giant, MA_NOTOWNED);
1006 PROC_LOCK_ASSERT(p, MA_OWNED);
1007 while (thread_suspend_check_needed()) {
1008 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
1009 KASSERT(p->p_singlethread != NULL,
1010 ("singlethread not set"));
1012 * The only suspension in action is a
1013 * single-threading. Single threader need not stop.
1014 * It is safe to access p->p_singlethread unlocked
1015 * because it can only be set to our address by us.
1017 if (p->p_singlethread == td)
1018 return (0); /* Exempt from stopping. */
1020 if ((p->p_flag & P_SINGLE_EXIT) && return_instead)
1023 /* Should we goto user boundary if we didn't come from there? */
1024 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
1025 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
1029 * Ignore suspend requests if they are deferred.
1031 if ((td->td_flags & TDF_SBDRY) != 0) {
1032 KASSERT(return_instead,
1033 ("TDF_SBDRY set for unsafe thread_suspend_check"));
1034 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) !=
1035 (TDF_SEINTR | TDF_SERESTART),
1036 ("both TDF_SEINTR and TDF_SERESTART"));
1037 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0);
1041 * If the process is waiting for us to exit,
1042 * this thread should just suicide.
1043 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
1045 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
1049 * Allow Linux emulation layer to do some work
1050 * before thread suicide.
1052 if (__predict_false(p->p_sysent->sv_thread_detach != NULL))
1053 (p->p_sysent->sv_thread_detach)(td);
1054 umtx_thread_exit(td);
1056 panic("stopped thread did not exit");
1061 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
1062 if (p->p_numthreads == p->p_suspcount + 1) {
1063 thread_lock(p->p_singlethread);
1064 wakeup_swapper = thread_unsuspend_one(
1065 p->p_singlethread, p, false);
1073 * When a thread suspends, it just
1074 * gets taken off all queues.
1076 thread_suspend_one(td);
1077 if (return_instead == 0) {
1078 p->p_boundary_count++;
1079 td->td_flags |= TDF_BOUNDARY;
1082 mi_switch(SW_INVOL | SWT_SUSPEND);
1089 * Check for possible stops and suspensions while executing a
1090 * casueword or similar transiently failing operation.
1092 * The sleep argument controls whether the function can handle a stop
1093 * request itself or it should return ERESTART and the request is
1094 * proceed at the kernel/user boundary in ast.
1096 * Typically, when retrying due to casueword(9) failure (rv == 1), we
1097 * should handle the stop requests there, with exception of cases when
1098 * the thread owns a kernel resource, for instance busied the umtx
1099 * key, or when functions return immediately if thread_check_susp()
1100 * returned non-zero. On the other hand, retrying the whole lock
1101 * operation, we better not stop there but delegate the handling to
1104 * If the request is for thread termination P_SINGLE_EXIT, we cannot
1105 * handle it at all, and simply return EINTR.
1108 thread_check_susp(struct thread *td, bool sleep)
1114 * The check for TDF_NEEDSUSPCHK is racy, but it is enough to
1115 * eventually break the lockstep loop.
1117 if ((td->td_flags & TDF_NEEDSUSPCHK) == 0)
1122 if (p->p_flag & P_SINGLE_EXIT)
1124 else if (P_SHOULDSTOP(p) ||
1125 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND)))
1126 error = sleep ? thread_suspend_check(0) : ERESTART;
1132 thread_suspend_switch(struct thread *td, struct proc *p)
1135 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
1136 PROC_LOCK_ASSERT(p, MA_OWNED);
1137 PROC_SLOCK_ASSERT(p, MA_OWNED);
1139 * We implement thread_suspend_one in stages here to avoid
1140 * dropping the proc lock while the thread lock is owned.
1142 if (p == td->td_proc) {
1148 td->td_flags &= ~TDF_NEEDSUSPCHK;
1149 TD_SET_SUSPENDED(td);
1153 mi_switch(SW_VOL | SWT_SUSPEND);
1160 thread_suspend_one(struct thread *td)
1165 PROC_SLOCK_ASSERT(p, MA_OWNED);
1166 THREAD_LOCK_ASSERT(td, MA_OWNED);
1167 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
1169 td->td_flags &= ~TDF_NEEDSUSPCHK;
1170 TD_SET_SUSPENDED(td);
1175 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary)
1178 THREAD_LOCK_ASSERT(td, MA_OWNED);
1179 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
1180 TD_CLR_SUSPENDED(td);
1181 td->td_flags &= ~TDF_ALLPROCSUSP;
1182 if (td->td_proc == p) {
1183 PROC_SLOCK_ASSERT(p, MA_OWNED);
1185 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) {
1186 td->td_flags &= ~TDF_BOUNDARY;
1187 p->p_boundary_count--;
1190 return (setrunnable(td, 0));
1194 * Allow all threads blocked by single threading to continue running.
1197 thread_unsuspend(struct proc *p)
1202 PROC_LOCK_ASSERT(p, MA_OWNED);
1203 PROC_SLOCK_ASSERT(p, MA_OWNED);
1205 if (!P_SHOULDSTOP(p)) {
1206 FOREACH_THREAD_IN_PROC(p, td) {
1208 if (TD_IS_SUSPENDED(td)) {
1209 wakeup_swapper |= thread_unsuspend_one(td, p,
1214 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
1215 p->p_numthreads == p->p_suspcount) {
1217 * Stopping everything also did the job for the single
1218 * threading request. Now we've downgraded to single-threaded,
1221 if (p->p_singlethread->td_proc == p) {
1222 thread_lock(p->p_singlethread);
1223 wakeup_swapper = thread_unsuspend_one(
1224 p->p_singlethread, p, false);
1232 * End the single threading mode..
1235 thread_single_end(struct proc *p, int mode)
1240 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
1241 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
1242 ("invalid mode %d", mode));
1243 PROC_LOCK_ASSERT(p, MA_OWNED);
1244 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) ||
1245 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0),
1246 ("mode %d does not match P_TOTAL_STOP", mode));
1247 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread,
1248 ("thread_single_end from other thread %p %p",
1249 curthread, p->p_singlethread));
1250 KASSERT(mode != SINGLE_BOUNDARY ||
1251 (p->p_flag & P_SINGLE_BOUNDARY) != 0,
1252 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag));
1253 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY |
1256 p->p_singlethread = NULL;
1259 * If there are other threads they may now run,
1260 * unless of course there is a blanket 'stop order'
1261 * on the process. The single threader must be allowed
1262 * to continue however as this is a bad place to stop.
1264 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) {
1265 FOREACH_THREAD_IN_PROC(p, td) {
1267 if (TD_IS_SUSPENDED(td)) {
1268 wakeup_swapper |= thread_unsuspend_one(td, p,
1269 mode == SINGLE_BOUNDARY);
1274 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0,
1275 ("inconsistent boundary count %d", p->p_boundary_count));
1282 thread_find(struct proc *p, lwpid_t tid)
1286 PROC_LOCK_ASSERT(p, MA_OWNED);
1287 FOREACH_THREAD_IN_PROC(p, td) {
1288 if (td->td_tid == tid)
1294 /* Locate a thread by number; return with proc lock held. */
1296 tdfind(lwpid_t tid, pid_t pid)
1298 #define RUN_THRESH 16
1302 rw_rlock(&tidhash_lock);
1303 LIST_FOREACH(td, TIDHASH(tid), td_hash) {
1304 if (td->td_tid == tid) {
1305 if (pid != -1 && td->td_proc->p_pid != pid) {
1309 PROC_LOCK(td->td_proc);
1310 if (td->td_proc->p_state == PRS_NEW) {
1311 PROC_UNLOCK(td->td_proc);
1315 if (run > RUN_THRESH) {
1316 if (rw_try_upgrade(&tidhash_lock)) {
1317 LIST_REMOVE(td, td_hash);
1318 LIST_INSERT_HEAD(TIDHASH(td->td_tid),
1320 rw_wunlock(&tidhash_lock);
1328 rw_runlock(&tidhash_lock);
1333 tidhash_add(struct thread *td)
1335 rw_wlock(&tidhash_lock);
1336 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
1337 rw_wunlock(&tidhash_lock);
1341 tidhash_remove(struct thread *td)
1343 rw_wlock(&tidhash_lock);
1344 LIST_REMOVE(td, td_hash);
1345 rw_wunlock(&tidhash_lock);