2 * SPDX-License-Identifier: BSD-2-Clause
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/param.h>
35 #include <sys/systm.h>
36 #include <sys/kernel.h>
39 #include <sys/mutex.h>
41 #include <sys/bitstring.h>
42 #include <sys/epoch.h>
43 #include <sys/rangelock.h>
44 #include <sys/resourcevar.h>
47 #include <sys/sched.h>
48 #include <sys/sleepqueue.h>
49 #include <sys/selinfo.h>
50 #include <sys/syscallsubr.h>
51 #include <sys/dtrace_bsd.h>
52 #include <sys/sysent.h>
53 #include <sys/turnstile.h>
54 #include <sys/taskqueue.h>
56 #include <sys/rwlock.h>
57 #include <sys/umtxvar.h>
58 #include <sys/vmmeter.h>
59 #include <sys/cpuset.h>
61 #include <sys/pmckern.h>
65 #include <security/audit/audit.h>
69 #include <vm/vm_extern.h>
71 #include <vm/vm_phys.h>
72 #include <sys/eventhandler.h>
75 * Asserts below verify the stability of struct thread and struct proc
76 * layout, as exposed by KBI to modules. On head, the KBI is allowed
77 * to drift, change to the structures must be accompanied by the
80 * On the stable branches after KBI freeze, conditions must not be
81 * violated. Typically new fields are moved to the end of the
85 _Static_assert(offsetof(struct thread, td_flags) == 0x108,
86 "struct thread KBI td_flags");
87 _Static_assert(offsetof(struct thread, td_pflags) == 0x114,
88 "struct thread KBI td_pflags");
89 _Static_assert(offsetof(struct thread, td_frame) == 0x4b8,
90 "struct thread KBI td_frame");
91 _Static_assert(offsetof(struct thread, td_emuldata) == 0x6c0,
92 "struct thread KBI td_emuldata");
93 _Static_assert(offsetof(struct proc, p_flag) == 0xb8,
94 "struct proc KBI p_flag");
95 _Static_assert(offsetof(struct proc, p_pid) == 0xc4,
96 "struct proc KBI p_pid");
97 _Static_assert(offsetof(struct proc, p_filemon) == 0x3c8,
98 "struct proc KBI p_filemon");
99 _Static_assert(offsetof(struct proc, p_comm) == 0x3e0,
100 "struct proc KBI p_comm");
101 _Static_assert(offsetof(struct proc, p_emuldata) == 0x4d0,
102 "struct proc KBI p_emuldata");
105 _Static_assert(offsetof(struct thread, td_flags) == 0x9c,
106 "struct thread KBI td_flags");
107 _Static_assert(offsetof(struct thread, td_pflags) == 0xa8,
108 "struct thread KBI td_pflags");
109 _Static_assert(offsetof(struct thread, td_frame) == 0x318,
110 "struct thread KBI td_frame");
111 _Static_assert(offsetof(struct thread, td_emuldata) == 0x35c,
112 "struct thread KBI td_emuldata");
113 _Static_assert(offsetof(struct proc, p_flag) == 0x6c,
114 "struct proc KBI p_flag");
115 _Static_assert(offsetof(struct proc, p_pid) == 0x78,
116 "struct proc KBI p_pid");
117 _Static_assert(offsetof(struct proc, p_filemon) == 0x270,
118 "struct proc KBI p_filemon");
119 _Static_assert(offsetof(struct proc, p_comm) == 0x284,
120 "struct proc KBI p_comm");
121 _Static_assert(offsetof(struct proc, p_emuldata) == 0x318,
122 "struct proc KBI p_emuldata");
125 SDT_PROVIDER_DECLARE(proc);
126 SDT_PROBE_DEFINE(proc, , , lwp__exit);
129 * thread related storage.
131 static uma_zone_t thread_zone;
133 struct thread_domain_data {
134 struct thread *tdd_zombies;
136 } __aligned(CACHE_LINE_SIZE);
138 static struct thread_domain_data thread_domain_data[MAXMEMDOM];
140 static struct task thread_reap_task;
141 static struct callout thread_reap_callout;
143 static void thread_zombie(struct thread *);
144 static void thread_reap(void);
145 static void thread_reap_all(void);
146 static void thread_reap_task_cb(void *, int);
147 static void thread_reap_callout_cb(void *);
148 static int thread_unsuspend_one(struct thread *td, struct proc *p,
150 static void thread_free_batched(struct thread *td);
152 static __exclusive_cache_line struct mtx tid_lock;
153 static bitstr_t *tid_bitmap;
155 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash");
157 static int maxthread;
158 SYSCTL_INT(_kern, OID_AUTO, maxthread, CTLFLAG_RDTUN,
159 &maxthread, 0, "Maximum number of threads");
161 static __exclusive_cache_line int nthreads;
163 static LIST_HEAD(tidhashhead, thread) *tidhashtbl;
164 static u_long tidhash;
165 static u_long tidhashlock;
166 static struct rwlock *tidhashtbl_lock;
167 #define TIDHASH(tid) (&tidhashtbl[(tid) & tidhash])
168 #define TIDHASHLOCK(tid) (&tidhashtbl_lock[(tid) & tidhashlock])
170 EVENTHANDLER_LIST_DEFINE(thread_ctor);
171 EVENTHANDLER_LIST_DEFINE(thread_dtor);
172 EVENTHANDLER_LIST_DEFINE(thread_init);
173 EVENTHANDLER_LIST_DEFINE(thread_fini);
176 thread_count_inc_try(void)
180 nthreads_new = atomic_fetchadd_int(&nthreads, 1) + 1;
181 if (nthreads_new >= maxthread - 100) {
182 if (priv_check_cred(curthread->td_ucred, PRIV_MAXPROC) != 0 ||
183 nthreads_new >= maxthread) {
184 atomic_subtract_int(&nthreads, 1);
192 thread_count_inc(void)
194 static struct timeval lastfail;
198 if (thread_count_inc_try()) {
203 if (thread_count_inc_try()) {
207 if (ppsratecheck(&lastfail, &curfail, 1)) {
208 printf("maxthread limit exceeded by uid %u "
209 "(pid %d); consider increasing kern.maxthread\n",
210 curthread->td_ucred->cr_ruid, curproc->p_pid);
216 thread_count_sub(int n)
219 atomic_subtract_int(&nthreads, n);
223 thread_count_dec(void)
232 static lwpid_t trytid;
237 * It is an invariant that the bitmap is big enough to hold maxthread
238 * IDs. If we got to this point there has to be at least one free.
240 if (trytid >= maxthread)
242 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid);
244 KASSERT(trytid != 0, ("unexpectedly ran out of IDs"));
246 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid);
247 KASSERT(tid != -1, ("unexpectedly ran out of IDs"));
249 bit_set(tid_bitmap, tid);
251 mtx_unlock(&tid_lock);
252 return (tid + NO_PID);
256 tid_free_locked(lwpid_t rtid)
260 mtx_assert(&tid_lock, MA_OWNED);
261 KASSERT(rtid >= NO_PID,
262 ("%s: invalid tid %d\n", __func__, rtid));
264 KASSERT(bit_test(tid_bitmap, tid) != 0,
265 ("thread ID %d not allocated\n", rtid));
266 bit_clear(tid_bitmap, tid);
270 tid_free(lwpid_t rtid)
274 tid_free_locked(rtid);
275 mtx_unlock(&tid_lock);
279 tid_free_batch(lwpid_t *batch, int n)
284 for (i = 0; i < n; i++) {
285 tid_free_locked(batch[i]);
287 mtx_unlock(&tid_lock);
291 * Batching for thread reapping.
299 tidbatch_prep(struct tidbatch *tb)
306 tidbatch_add(struct tidbatch *tb, struct thread *td)
309 KASSERT(tb->n < nitems(tb->tab),
310 ("%s: count too high %d", __func__, tb->n));
311 tb->tab[tb->n] = td->td_tid;
316 tidbatch_process(struct tidbatch *tb)
319 KASSERT(tb->n <= nitems(tb->tab),
320 ("%s: count too high %d", __func__, tb->n));
321 if (tb->n == nitems(tb->tab)) {
322 tid_free_batch(tb->tab, tb->n);
328 tidbatch_final(struct tidbatch *tb)
331 KASSERT(tb->n <= nitems(tb->tab),
332 ("%s: count too high %d", __func__, tb->n));
334 tid_free_batch(tb->tab, tb->n);
339 * Batching thread count free, for consistency
341 struct tdcountbatch {
346 tdcountbatch_prep(struct tdcountbatch *tb)
353 tdcountbatch_add(struct tdcountbatch *tb, struct thread *td __unused)
360 tdcountbatch_process(struct tdcountbatch *tb)
364 thread_count_sub(tb->n);
370 tdcountbatch_final(struct tdcountbatch *tb)
374 thread_count_sub(tb->n);
379 * Prepare a thread for use.
382 thread_ctor(void *mem, int size, void *arg, int flags)
386 td = (struct thread *)mem;
387 TD_SET_STATE(td, TDS_INACTIVE);
388 td->td_lastcpu = td->td_oncpu = NOCPU;
391 * Note that td_critnest begins life as 1 because the thread is not
392 * running and is thereby implicitly waiting to be on the receiving
393 * end of a context switch.
396 td->td_lend_user_pri = PRI_MAX;
398 audit_thread_alloc(td);
401 kdtrace_thread_ctor(td);
403 umtx_thread_alloc(td);
404 MPASS(td->td_sel == NULL);
409 * Reclaim a thread after use.
412 thread_dtor(void *mem, int size, void *arg)
416 td = (struct thread *)mem;
419 /* Verify that this thread is in a safe state to free. */
420 switch (TD_GET_STATE(td)) {
426 * We must never unlink a thread that is in one of
427 * these states, because it is currently active.
429 panic("bad state for thread unlinking");
434 panic("bad thread state");
439 audit_thread_free(td);
442 kdtrace_thread_dtor(td);
444 /* Free all OSD associated to this thread. */
451 * Initialize type-stable parts of a thread (when newly created).
454 thread_init(void *mem, int size, int flags)
458 td = (struct thread *)mem;
460 td->td_allocdomain = vm_phys_domain(vtophys(td));
461 td->td_sleepqueue = sleepq_alloc();
462 td->td_turnstile = turnstile_alloc();
464 EVENTHANDLER_DIRECT_INVOKE(thread_init, td);
465 umtx_thread_init(td);
472 * Tear down type-stable parts of a thread (just before being discarded).
475 thread_fini(void *mem, int size)
479 td = (struct thread *)mem;
480 EVENTHANDLER_DIRECT_INVOKE(thread_fini, td);
481 rlqentry_free(td->td_rlqe);
482 turnstile_free(td->td_turnstile);
483 sleepq_free(td->td_sleepqueue);
484 umtx_thread_fini(td);
485 MPASS(td->td_sel == NULL);
489 * For a newly created process,
490 * link up all the structures and its initial threads etc.
492 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc.
493 * proc_dtor() (should go away)
497 proc_linkup0(struct proc *p, struct thread *td)
499 TAILQ_INIT(&p->p_threads); /* all threads in proc */
504 proc_linkup(struct proc *p, struct thread *td)
507 sigqueue_init(&p->p_sigqueue, p);
508 p->p_ksi = ksiginfo_alloc(M_WAITOK);
509 if (p->p_ksi != NULL) {
510 /* XXX p_ksi may be null if ksiginfo zone is not ready */
511 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS;
513 LIST_INIT(&p->p_mqnotifier);
519 ast_suspend(struct thread *td, int tda __unused)
525 * We need to check to see if we have to exit or wait due to a
526 * single threading requirement or some other STOP condition.
529 thread_suspend_check(0);
533 extern int max_threads_per_proc;
536 * Initialize global thread allocation resources.
545 * Place an upper limit on threads which can be allocated.
547 * Note that other factors may make the de facto limit much lower.
549 * Platform limits are somewhat arbitrary but deemed "more than good
550 * enough" for the foreseable future.
552 if (maxthread == 0) {
554 maxthread = MIN(maxproc * max_threads_per_proc, 1000000);
556 maxthread = MIN(maxproc * max_threads_per_proc, 100000);
560 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
561 tid_bitmap = bit_alloc(maxthread, M_TIDHASH, M_WAITOK);
567 if (tid0 != THREAD0_TID)
568 panic("tid0 %d != %d\n", tid0, THREAD0_TID);
571 * Thread structures are specially aligned so that (at least) the
572 * 5 lower bits of a pointer to 'struct thead' must be 0. These bits
573 * are used by synchronization primitives to store flags in pointers to
576 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
577 thread_ctor, thread_dtor, thread_init, thread_fini,
578 UMA_ALIGN_CACHE_AND_MASK(32 - 1), UMA_ZONE_NOFREE);
579 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash);
580 tidhashlock = (tidhash + 1) / 64;
583 tidhashtbl_lock = malloc(sizeof(*tidhashtbl_lock) * (tidhashlock + 1),
584 M_TIDHASH, M_WAITOK | M_ZERO);
585 for (i = 0; i < tidhashlock + 1; i++)
586 rw_init(&tidhashtbl_lock[i], "tidhash");
588 TASK_INIT(&thread_reap_task, 0, thread_reap_task_cb, NULL);
589 callout_init(&thread_reap_callout, 1);
590 callout_reset(&thread_reap_callout, 5 * hz,
591 thread_reap_callout_cb, NULL);
592 ast_register(TDA_SUSPEND, ASTR_ASTF_REQUIRED, 0, ast_suspend);
596 * Place an unused thread on the zombie list.
599 thread_zombie(struct thread *td)
601 struct thread_domain_data *tdd;
604 tdd = &thread_domain_data[td->td_allocdomain];
605 ztd = atomic_load_ptr(&tdd->tdd_zombies);
608 if (atomic_fcmpset_rel_ptr((uintptr_t *)&tdd->tdd_zombies,
609 (uintptr_t *)&ztd, (uintptr_t)td))
616 * Release a thread that has exited after cpu_throw().
619 thread_stash(struct thread *td)
621 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1);
626 * Reap zombies from passed domain.
629 thread_reap_domain(struct thread_domain_data *tdd)
631 struct thread *itd, *ntd;
632 struct tidbatch tidbatch;
633 struct credbatch credbatch;
634 struct limbatch limbatch;
635 struct tdcountbatch tdcountbatch;
638 * Reading upfront is pessimal if followed by concurrent atomic_swap,
639 * but most of the time the list is empty.
641 if (tdd->tdd_zombies == NULL)
644 itd = (struct thread *)atomic_swap_ptr((uintptr_t *)&tdd->tdd_zombies,
650 * Multiple CPUs can get here, the race is fine as ticks is only
653 tdd->tdd_reapticks = ticks;
655 tidbatch_prep(&tidbatch);
656 credbatch_prep(&credbatch);
657 limbatch_prep(&limbatch);
658 tdcountbatch_prep(&tdcountbatch);
660 while (itd != NULL) {
661 ntd = itd->td_zombie;
662 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, itd);
664 tidbatch_add(&tidbatch, itd);
665 credbatch_add(&credbatch, itd);
666 limbatch_add(&limbatch, itd);
667 tdcountbatch_add(&tdcountbatch, itd);
669 thread_free_batched(itd);
671 tidbatch_process(&tidbatch);
672 credbatch_process(&credbatch);
673 limbatch_process(&limbatch);
674 tdcountbatch_process(&tdcountbatch);
679 tidbatch_final(&tidbatch);
680 credbatch_final(&credbatch);
681 limbatch_final(&limbatch);
682 tdcountbatch_final(&tdcountbatch);
686 * Reap zombies from all domains.
689 thread_reap_all(void)
691 struct thread_domain_data *tdd;
694 domain = PCPU_GET(domain);
695 for (i = 0; i < vm_ndomains; i++) {
696 tdd = &thread_domain_data[(i + domain) % vm_ndomains];
697 thread_reap_domain(tdd);
702 * Reap zombies from local domain.
707 struct thread_domain_data *tdd;
710 domain = PCPU_GET(domain);
711 tdd = &thread_domain_data[domain];
713 thread_reap_domain(tdd);
717 thread_reap_task_cb(void *arg __unused, int pending __unused)
724 thread_reap_callout_cb(void *arg __unused)
726 struct thread_domain_data *tdd;
727 int i, cticks, lticks;
731 cticks = atomic_load_int(&ticks);
732 for (i = 0; i < vm_ndomains; i++) {
733 tdd = &thread_domain_data[i];
734 lticks = tdd->tdd_reapticks;
735 if (tdd->tdd_zombies != NULL &&
736 (u_int)(cticks - lticks) > 5 * hz) {
743 taskqueue_enqueue(taskqueue_thread, &thread_reap_task);
744 callout_reset(&thread_reap_callout, 5 * hz,
745 thread_reap_callout_cb, NULL);
749 * Calling this function guarantees that any thread that exited before
750 * the call is reaped when the function returns. By 'exited' we mean
751 * a thread removed from the process linkage with thread_unlink().
752 * Practically this means that caller must lock/unlock corresponding
753 * process lock before the call, to synchronize with thread_exit().
756 thread_reap_barrier(void)
761 * First do context switches to each CPU to ensure that all
762 * PCPU pc_deadthreads are moved to zombie list.
764 quiesce_all_cpus("", PDROP);
767 * Second, fire the task in the same thread as normal
768 * thread_reap() is done, to serialize reaping.
770 t = malloc(sizeof(*t), M_TEMP, M_WAITOK);
771 TASK_INIT(t, 0, thread_reap_task_cb, t);
772 taskqueue_enqueue(taskqueue_thread, t);
773 taskqueue_drain(taskqueue_thread, t);
781 thread_alloc(int pages)
786 if (!thread_count_inc()) {
791 td = uma_zalloc(thread_zone, M_WAITOK);
792 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
793 if (!vm_thread_new(td, pages)) {
794 uma_zfree(thread_zone, td);
800 bzero(&td->td_sa.args, sizeof(td->td_sa.args));
801 kmsan_thread_alloc(td);
802 cpu_thread_alloc(td);
803 EVENTHANDLER_DIRECT_INVOKE(thread_ctor, td);
808 thread_alloc_stack(struct thread *td, int pages)
811 KASSERT(td->td_kstack == 0,
812 ("thread_alloc_stack called on a thread with kstack"));
813 if (!vm_thread_new(td, pages))
815 cpu_thread_alloc(td);
820 * Deallocate a thread.
823 thread_free_batched(struct thread *td)
826 lock_profile_thread_exit(td);
828 cpuset_rel(td->td_cpuset);
829 td->td_cpuset = NULL;
831 if (td->td_kstack != 0)
832 vm_thread_dispose(td);
833 callout_drain(&td->td_slpcallout);
835 * Freeing handled by the caller.
838 kmsan_thread_free(td);
839 uma_zfree(thread_zone, td);
843 thread_free(struct thread *td)
847 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, td);
849 thread_free_batched(td);
855 thread_cow_get_proc(struct thread *newtd, struct proc *p)
858 PROC_LOCK_ASSERT(p, MA_OWNED);
859 newtd->td_realucred = crcowget(p->p_ucred);
860 newtd->td_ucred = newtd->td_realucred;
861 newtd->td_limit = lim_hold(p->p_limit);
862 newtd->td_cowgen = p->p_cowgen;
866 thread_cow_get(struct thread *newtd, struct thread *td)
869 MPASS(td->td_realucred == td->td_ucred);
870 newtd->td_realucred = crcowget(td->td_realucred);
871 newtd->td_ucred = newtd->td_realucred;
872 newtd->td_limit = lim_hold(td->td_limit);
873 newtd->td_cowgen = td->td_cowgen;
877 thread_cow_free(struct thread *td)
880 if (td->td_realucred != NULL)
882 if (td->td_limit != NULL)
883 lim_free(td->td_limit);
887 thread_cow_update(struct thread *td)
890 struct ucred *oldcred;
891 struct plimit *oldlimit;
895 oldcred = crcowsync();
896 oldlimit = lim_cowsync();
897 td->td_cowgen = p->p_cowgen;
901 if (oldlimit != NULL)
906 thread_cow_synced(struct thread *td)
911 PROC_LOCK_ASSERT(p, MA_OWNED);
912 MPASS(td->td_cowgen != p->p_cowgen);
913 MPASS(td->td_ucred == p->p_ucred);
914 MPASS(td->td_limit == p->p_limit);
915 td->td_cowgen = p->p_cowgen;
919 * Discard the current thread and exit from its context.
920 * Always called with scheduler locked.
922 * Because we can't free a thread while we're operating under its context,
923 * push the current thread into our CPU's deadthread holder. This means
924 * we needn't worry about someone else grabbing our context before we
930 uint64_t runtime, new_switchtime;
939 PROC_SLOCK_ASSERT(p, MA_OWNED);
940 mtx_assert(&Giant, MA_NOTOWNED);
942 PROC_LOCK_ASSERT(p, MA_OWNED);
943 KASSERT(p != NULL, ("thread exiting without a process"));
944 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
945 (long)p->p_pid, td->td_name);
946 SDT_PROBE0(proc, , , lwp__exit);
947 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
948 MPASS(td->td_realucred == td->td_ucred);
951 * drop FPU & debug register state storage, or any other
952 * architecture specific resources that
953 * would not be on a new untouched process.
958 * The last thread is left attached to the process
959 * So that the whole bundle gets recycled. Skip
960 * all this stuff if we never had threads.
961 * EXIT clears all sign of other threads when
962 * it goes to single threading, so the last thread always
963 * takes the short path.
965 if (p->p_flag & P_HADTHREADS) {
966 if (p->p_numthreads > 1) {
967 atomic_add_int(&td->td_proc->p_exitthreads, 1);
969 td2 = FIRST_THREAD_IN_PROC(p);
970 sched_exit_thread(td2, td);
973 * The test below is NOT true if we are the
974 * sole exiting thread. P_STOPPED_SINGLE is unset
975 * in exit1() after it is the only survivor.
977 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
978 if (p->p_numthreads == p->p_suspcount) {
979 thread_lock(p->p_singlethread);
980 wakeup_swapper = thread_unsuspend_one(
981 p->p_singlethread, p, false);
987 PCPU_SET(deadthread, td);
990 * The last thread is exiting.. but not through exit()
992 panic ("thread_exit: Last thread exiting on its own");
997 * If this thread is part of a process that is being tracked by hwpmc(4),
998 * inform the module of the thread's impending exit.
1000 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) {
1001 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
1002 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT, NULL);
1003 } else if (PMC_SYSTEM_SAMPLING_ACTIVE())
1004 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL);
1011 /* Do the same timestamp bookkeeping that mi_switch() would do. */
1012 new_switchtime = cpu_ticks();
1013 runtime = new_switchtime - PCPU_GET(switchtime);
1014 td->td_runtime += runtime;
1015 td->td_incruntime += runtime;
1016 PCPU_SET(switchtime, new_switchtime);
1017 PCPU_SET(switchticks, ticks);
1018 VM_CNT_INC(v_swtch);
1020 /* Save our resource usage in our process. */
1021 td->td_ru.ru_nvcsw++;
1022 ruxagg_locked(p, td);
1023 rucollect(&p->p_ru, &td->td_ru);
1026 TD_SET_STATE(td, TDS_INACTIVE);
1028 witness_thread_exit(td);
1030 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
1032 panic("I'm a teapot!");
1037 * Do any thread specific cleanups that may be needed in wait()
1038 * called with Giant, proc and schedlock not held.
1041 thread_wait(struct proc *p)
1045 mtx_assert(&Giant, MA_NOTOWNED);
1046 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()"));
1047 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking"));
1048 td = FIRST_THREAD_IN_PROC(p);
1049 /* Lock the last thread so we spin until it exits cpu_throw(). */
1052 lock_profile_thread_exit(td);
1053 cpuset_rel(td->td_cpuset);
1054 td->td_cpuset = NULL;
1055 cpu_thread_clean(td);
1056 thread_cow_free(td);
1057 callout_drain(&td->td_slpcallout);
1058 thread_reap(); /* check for zombie threads etc. */
1062 * Link a thread to a process.
1063 * set up anything that needs to be initialized for it to
1064 * be used by the process.
1067 thread_link(struct thread *td, struct proc *p)
1071 * XXX This can't be enabled because it's called for proc0 before
1072 * its lock has been created.
1073 * PROC_LOCK_ASSERT(p, MA_OWNED);
1075 TD_SET_STATE(td, TDS_INACTIVE);
1077 td->td_flags = TDF_INMEM;
1079 LIST_INIT(&td->td_contested);
1080 LIST_INIT(&td->td_lprof[0]);
1081 LIST_INIT(&td->td_lprof[1]);
1083 SLIST_INIT(&td->td_epochs);
1085 sigqueue_init(&td->td_sigqueue, p);
1086 callout_init(&td->td_slpcallout, 1);
1087 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist);
1096 thread_unlink(struct thread *td)
1098 struct proc *p = td->td_proc;
1100 PROC_LOCK_ASSERT(p, MA_OWNED);
1102 MPASS(SLIST_EMPTY(&td->td_epochs));
1105 TAILQ_REMOVE(&p->p_threads, td, td_plist);
1107 /* could clear a few other things here */
1108 /* Must NOT clear links to proc! */
1112 calc_remaining(struct proc *p, int mode)
1116 PROC_LOCK_ASSERT(p, MA_OWNED);
1117 PROC_SLOCK_ASSERT(p, MA_OWNED);
1118 if (mode == SINGLE_EXIT)
1119 remaining = p->p_numthreads;
1120 else if (mode == SINGLE_BOUNDARY)
1121 remaining = p->p_numthreads - p->p_boundary_count;
1122 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC)
1123 remaining = p->p_numthreads - p->p_suspcount;
1125 panic("calc_remaining: wrong mode %d", mode);
1130 remain_for_mode(int mode)
1133 return (mode == SINGLE_ALLPROC ? 0 : 1);
1137 weed_inhib(int mode, struct thread *td2, struct proc *p)
1141 PROC_LOCK_ASSERT(p, MA_OWNED);
1142 PROC_SLOCK_ASSERT(p, MA_OWNED);
1143 THREAD_LOCK_ASSERT(td2, MA_OWNED);
1148 * Since the thread lock is dropped by the scheduler we have
1149 * to retry to check for races.
1154 if (TD_IS_SUSPENDED(td2)) {
1155 wakeup_swapper |= thread_unsuspend_one(td2, p, true);
1159 if (TD_CAN_ABORT(td2)) {
1160 wakeup_swapper |= sleepq_abort(td2, EINTR);
1161 return (wakeup_swapper);
1164 case SINGLE_BOUNDARY:
1165 case SINGLE_NO_EXIT:
1166 if (TD_IS_SUSPENDED(td2) &&
1167 (td2->td_flags & TDF_BOUNDARY) == 0) {
1168 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
1172 if (TD_CAN_ABORT(td2)) {
1173 wakeup_swapper |= sleepq_abort(td2, ERESTART);
1174 return (wakeup_swapper);
1177 case SINGLE_ALLPROC:
1179 * ALLPROC suspend tries to avoid spurious EINTR for
1180 * threads sleeping interruptable, by suspending the
1181 * thread directly, similarly to sig_suspend_threads().
1182 * Since such sleep is not neccessary performed at the user
1183 * boundary, TDF_ALLPROCSUSP is used to avoid immediate
1186 if (TD_IS_SUSPENDED(td2) &&
1187 (td2->td_flags & TDF_ALLPROCSUSP) == 0) {
1188 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
1192 if (TD_CAN_ABORT(td2)) {
1193 td2->td_flags |= TDF_ALLPROCSUSP;
1194 wakeup_swapper |= sleepq_abort(td2, ERESTART);
1195 return (wakeup_swapper);
1202 return (wakeup_swapper);
1206 * Enforce single-threading.
1208 * Returns 1 if the caller must abort (another thread is waiting to
1209 * exit the process or similar). Process is locked!
1210 * Returns 0 when you are successfully the only thread running.
1211 * A process has successfully single threaded in the suspend mode when
1212 * There are no threads in user mode. Threads in the kernel must be
1213 * allowed to continue until they get to the user boundary. They may even
1214 * copy out their return values and data before suspending. They may however be
1215 * accelerated in reaching the user boundary as we will wake up
1216 * any sleeping threads that are interruptable. (PCATCH).
1219 thread_single(struct proc *p, int mode)
1223 int remaining, wakeup_swapper;
1226 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
1227 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
1228 ("invalid mode %d", mode));
1230 * If allowing non-ALLPROC singlethreading for non-curproc
1231 * callers, calc_remaining() and remain_for_mode() should be
1232 * adjusted to also account for td->td_proc != p. For now
1233 * this is not implemented because it is not used.
1235 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) ||
1236 (mode != SINGLE_ALLPROC && td->td_proc == p),
1237 ("mode %d proc %p curproc %p", mode, p, td->td_proc));
1238 mtx_assert(&Giant, MA_NOTOWNED);
1239 PROC_LOCK_ASSERT(p, MA_OWNED);
1242 * Is someone already single threading?
1243 * Or may be singlethreading is not needed at all.
1245 if (mode == SINGLE_ALLPROC) {
1246 while ((p->p_flag & P_STOPPED_SINGLE) != 0) {
1247 if ((p->p_flag2 & P2_WEXIT) != 0)
1249 msleep(&p->p_flag, &p->p_mtx, PCATCH, "thrsgl", 0);
1251 } else if ((p->p_flag & P_HADTHREADS) == 0)
1253 if (p->p_singlethread != NULL && p->p_singlethread != td)
1256 if (mode == SINGLE_EXIT) {
1257 p->p_flag |= P_SINGLE_EXIT;
1258 p->p_flag &= ~P_SINGLE_BOUNDARY;
1260 p->p_flag &= ~P_SINGLE_EXIT;
1261 if (mode == SINGLE_BOUNDARY)
1262 p->p_flag |= P_SINGLE_BOUNDARY;
1264 p->p_flag &= ~P_SINGLE_BOUNDARY;
1266 if (mode == SINGLE_ALLPROC)
1267 p->p_flag |= P_TOTAL_STOP;
1268 p->p_flag |= P_STOPPED_SINGLE;
1270 p->p_singlethread = td;
1271 remaining = calc_remaining(p, mode);
1272 while (remaining != remain_for_mode(mode)) {
1273 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE)
1276 FOREACH_THREAD_IN_PROC(p, td2) {
1280 ast_sched_locked(td2, TDA_SUSPEND);
1281 if (TD_IS_INHIBITED(td2)) {
1282 wakeup_swapper |= weed_inhib(mode, td2, p);
1284 } else if (TD_IS_RUNNING(td2)) {
1285 forward_signal(td2);
1293 remaining = calc_remaining(p, mode);
1296 * Maybe we suspended some threads.. was it enough?
1298 if (remaining == remain_for_mode(mode))
1303 * Wake us up when everyone else has suspended.
1304 * In the mean time we suspend as well.
1306 thread_suspend_switch(td, p);
1307 remaining = calc_remaining(p, mode);
1309 if (mode == SINGLE_EXIT) {
1311 * Convert the process to an unthreaded process. The
1312 * SINGLE_EXIT is called by exit1() or execve(), in
1313 * both cases other threads must be retired.
1315 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads"));
1316 p->p_singlethread = NULL;
1317 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS);
1320 * Wait for any remaining threads to exit cpu_throw().
1322 while (p->p_exitthreads != 0) {
1325 sched_relinquish(td);
1329 } else if (mode == SINGLE_BOUNDARY) {
1331 * Wait until all suspended threads are removed from
1332 * the processors. The thread_suspend_check()
1333 * increments p_boundary_count while it is still
1334 * running, which makes it possible for the execve()
1335 * to destroy vmspace while our other threads are
1336 * still using the address space.
1338 * We lock the thread, which is only allowed to
1339 * succeed after context switch code finished using
1340 * the address space.
1342 FOREACH_THREAD_IN_PROC(p, td2) {
1346 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0,
1347 ("td %p not on boundary", td2));
1348 KASSERT(TD_IS_SUSPENDED(td2),
1349 ("td %p is not suspended", td2));
1358 thread_suspend_check_needed(void)
1365 PROC_LOCK_ASSERT(p, MA_OWNED);
1366 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 &&
1367 (td->td_dbgflags & TDB_SUSPEND) != 0));
1371 * Called in from locations that can safely check to see
1372 * whether we have to suspend or at least throttle for a
1373 * single-thread event (e.g. fork).
1375 * Such locations include userret().
1376 * If the "return_instead" argument is non zero, the thread must be able to
1377 * accept 0 (caller may continue), or 1 (caller must abort) as a result.
1379 * The 'return_instead' argument tells the function if it may do a
1380 * thread_exit() or suspend, or whether the caller must abort and back
1383 * If the thread that set the single_threading request has set the
1384 * P_SINGLE_EXIT bit in the process flags then this call will never return
1385 * if 'return_instead' is false, but will exit.
1387 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0
1388 *---------------+--------------------+---------------------
1389 * 0 | returns 0 | returns 0 or 1
1390 * | when ST ends | immediately
1391 *---------------+--------------------+---------------------
1392 * 1 | thread exits | returns 1
1394 * 0 = thread_exit() or suspension ok,
1395 * other = return error instead of stopping the thread.
1397 * While a full suspension is under effect, even a single threading
1398 * thread would be suspended if it made this call (but it shouldn't).
1399 * This call should only be made from places where
1400 * thread_exit() would be safe as that may be the outcome unless
1401 * return_instead is set.
1404 thread_suspend_check(int return_instead)
1412 mtx_assert(&Giant, MA_NOTOWNED);
1413 PROC_LOCK_ASSERT(p, MA_OWNED);
1414 while (thread_suspend_check_needed()) {
1415 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
1416 KASSERT(p->p_singlethread != NULL,
1417 ("singlethread not set"));
1419 * The only suspension in action is a
1420 * single-threading. Single threader need not stop.
1421 * It is safe to access p->p_singlethread unlocked
1422 * because it can only be set to our address by us.
1424 if (p->p_singlethread == td)
1425 return (0); /* Exempt from stopping. */
1427 if ((p->p_flag & P_SINGLE_EXIT) && return_instead)
1430 /* Should we goto user boundary if we didn't come from there? */
1431 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
1432 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
1436 * Ignore suspend requests if they are deferred.
1438 if ((td->td_flags & TDF_SBDRY) != 0) {
1439 KASSERT(return_instead,
1440 ("TDF_SBDRY set for unsafe thread_suspend_check"));
1441 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) !=
1442 (TDF_SEINTR | TDF_SERESTART),
1443 ("both TDF_SEINTR and TDF_SERESTART"));
1444 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0);
1448 * If the process is waiting for us to exit,
1449 * this thread should just suicide.
1450 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
1452 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
1456 * Allow Linux emulation layer to do some work
1457 * before thread suicide.
1459 if (__predict_false(p->p_sysent->sv_thread_detach != NULL))
1460 (p->p_sysent->sv_thread_detach)(td);
1461 umtx_thread_exit(td);
1463 panic("stopped thread did not exit");
1468 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
1469 if (p->p_numthreads == p->p_suspcount + 1) {
1470 thread_lock(p->p_singlethread);
1471 wakeup_swapper = thread_unsuspend_one(
1472 p->p_singlethread, p, false);
1480 * When a thread suspends, it just
1481 * gets taken off all queues.
1483 thread_suspend_one(td);
1484 if (return_instead == 0) {
1485 p->p_boundary_count++;
1486 td->td_flags |= TDF_BOUNDARY;
1489 mi_switch(SW_INVOL | SWT_SUSPEND);
1496 * Check for possible stops and suspensions while executing a
1497 * casueword or similar transiently failing operation.
1499 * The sleep argument controls whether the function can handle a stop
1500 * request itself or it should return ERESTART and the request is
1501 * proceed at the kernel/user boundary in ast.
1503 * Typically, when retrying due to casueword(9) failure (rv == 1), we
1504 * should handle the stop requests there, with exception of cases when
1505 * the thread owns a kernel resource, for instance busied the umtx
1506 * key, or when functions return immediately if thread_check_susp()
1507 * returned non-zero. On the other hand, retrying the whole lock
1508 * operation, we better not stop there but delegate the handling to
1511 * If the request is for thread termination P_SINGLE_EXIT, we cannot
1512 * handle it at all, and simply return EINTR.
1515 thread_check_susp(struct thread *td, bool sleep)
1521 * The check for TDA_SUSPEND is racy, but it is enough to
1522 * eventually break the lockstep loop.
1524 if (!td_ast_pending(td, TDA_SUSPEND))
1529 if (p->p_flag & P_SINGLE_EXIT)
1531 else if (P_SHOULDSTOP(p) ||
1532 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND)))
1533 error = sleep ? thread_suspend_check(0) : ERESTART;
1539 thread_suspend_switch(struct thread *td, struct proc *p)
1542 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
1543 PROC_LOCK_ASSERT(p, MA_OWNED);
1544 PROC_SLOCK_ASSERT(p, MA_OWNED);
1546 * We implement thread_suspend_one in stages here to avoid
1547 * dropping the proc lock while the thread lock is owned.
1549 if (p == td->td_proc) {
1555 ast_unsched_locked(td, TDA_SUSPEND);
1556 TD_SET_SUSPENDED(td);
1560 mi_switch(SW_VOL | SWT_SUSPEND);
1567 thread_suspend_one(struct thread *td)
1572 PROC_SLOCK_ASSERT(p, MA_OWNED);
1573 THREAD_LOCK_ASSERT(td, MA_OWNED);
1574 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
1576 ast_unsched_locked(td, TDA_SUSPEND);
1577 TD_SET_SUSPENDED(td);
1582 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary)
1585 THREAD_LOCK_ASSERT(td, MA_OWNED);
1586 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
1587 TD_CLR_SUSPENDED(td);
1588 td->td_flags &= ~TDF_ALLPROCSUSP;
1589 if (td->td_proc == p) {
1590 PROC_SLOCK_ASSERT(p, MA_OWNED);
1592 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) {
1593 td->td_flags &= ~TDF_BOUNDARY;
1594 p->p_boundary_count--;
1597 return (setrunnable(td, 0));
1601 thread_run_flash(struct thread *td)
1606 PROC_LOCK_ASSERT(p, MA_OWNED);
1608 if (TD_ON_SLEEPQ(td))
1609 sleepq_remove_nested(td);
1613 THREAD_LOCK_ASSERT(td, MA_OWNED);
1614 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
1616 TD_CLR_SUSPENDED(td);
1618 MPASS(p->p_suspcount > 0);
1621 if (setrunnable(td, 0))
1626 * Allow all threads blocked by single threading to continue running.
1629 thread_unsuspend(struct proc *p)
1634 PROC_LOCK_ASSERT(p, MA_OWNED);
1635 PROC_SLOCK_ASSERT(p, MA_OWNED);
1637 if (!P_SHOULDSTOP(p)) {
1638 FOREACH_THREAD_IN_PROC(p, td) {
1640 if (TD_IS_SUSPENDED(td))
1641 wakeup_swapper |= thread_unsuspend_one(td, p,
1646 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
1647 p->p_numthreads == p->p_suspcount) {
1649 * Stopping everything also did the job for the single
1650 * threading request. Now we've downgraded to single-threaded,
1653 if (p->p_singlethread->td_proc == p) {
1654 thread_lock(p->p_singlethread);
1655 wakeup_swapper = thread_unsuspend_one(
1656 p->p_singlethread, p, false);
1664 * End the single threading mode..
1667 thread_single_end(struct proc *p, int mode)
1672 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
1673 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
1674 ("invalid mode %d", mode));
1675 PROC_LOCK_ASSERT(p, MA_OWNED);
1676 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) ||
1677 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0),
1678 ("mode %d does not match P_TOTAL_STOP", mode));
1679 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread,
1680 ("thread_single_end from other thread %p %p",
1681 curthread, p->p_singlethread));
1682 KASSERT(mode != SINGLE_BOUNDARY ||
1683 (p->p_flag & P_SINGLE_BOUNDARY) != 0,
1684 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag));
1685 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY |
1688 p->p_singlethread = NULL;
1691 * If there are other threads they may now run,
1692 * unless of course there is a blanket 'stop order'
1693 * on the process. The single threader must be allowed
1694 * to continue however as this is a bad place to stop.
1696 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) {
1697 FOREACH_THREAD_IN_PROC(p, td) {
1699 if (TD_IS_SUSPENDED(td)) {
1700 wakeup_swapper |= thread_unsuspend_one(td, p,
1706 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0,
1707 ("inconsistent boundary count %d", p->p_boundary_count));
1715 * Locate a thread by number and return with proc lock held.
1717 * thread exit establishes proc -> tidhash lock ordering, but lookup
1718 * takes tidhash first and needs to return locked proc.
1720 * The problem is worked around by relying on type-safety of both
1721 * structures and doing the work in 2 steps:
1722 * - tidhash-locked lookup which saves both thread and proc pointers
1723 * - proc-locked verification that the found thread still matches
1726 tdfind_hash(lwpid_t tid, pid_t pid, struct proc **pp, struct thread **tdp)
1728 #define RUN_THRESH 16
1735 rw_rlock(TIDHASHLOCK(tid));
1737 LIST_FOREACH(td, TIDHASH(tid), td_hash) {
1738 if (td->td_tid != tid) {
1743 if (pid != -1 && p->p_pid != pid) {
1747 if (run > RUN_THRESH) {
1748 if (rw_try_upgrade(TIDHASHLOCK(tid))) {
1749 LIST_REMOVE(td, td_hash);
1750 LIST_INSERT_HEAD(TIDHASH(td->td_tid),
1752 rw_wunlock(TIDHASHLOCK(tid));
1760 rw_runlock(TIDHASHLOCK(tid));
1769 tdfind(lwpid_t tid, pid_t pid)
1775 if (td->td_tid == tid) {
1776 if (pid != -1 && td->td_proc->p_pid != pid)
1778 PROC_LOCK(td->td_proc);
1783 if (!tdfind_hash(tid, pid, &p, &td))
1786 if (td->td_tid != tid) {
1790 if (td->td_proc != p) {
1794 if (p->p_state == PRS_NEW) {
1803 tidhash_add(struct thread *td)
1805 rw_wlock(TIDHASHLOCK(td->td_tid));
1806 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
1807 rw_wunlock(TIDHASHLOCK(td->td_tid));
1811 tidhash_remove(struct thread *td)
1814 rw_wlock(TIDHASHLOCK(td->td_tid));
1815 LIST_REMOVE(td, td_hash);
1816 rw_wunlock(TIDHASHLOCK(td->td_tid));