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/bitstring.h>
44 #include <sys/epoch.h>
45 #include <sys/rangelock.h>
46 #include <sys/resourcevar.h>
49 #include <sys/sched.h>
50 #include <sys/sleepqueue.h>
51 #include <sys/selinfo.h>
52 #include <sys/syscallsubr.h>
53 #include <sys/dtrace_bsd.h>
54 #include <sys/sysent.h>
55 #include <sys/turnstile.h>
56 #include <sys/taskqueue.h>
58 #include <sys/rwlock.h>
60 #include <sys/vmmeter.h>
61 #include <sys/cpuset.h>
63 #include <sys/pmckern.h>
67 #include <security/audit/audit.h>
71 #include <vm/vm_extern.h>
73 #include <vm/vm_phys.h>
74 #include <sys/eventhandler.h>
77 * Asserts below verify the stability of struct thread and struct proc
78 * layout, as exposed by KBI to modules. On head, the KBI is allowed
79 * to drift, change to the structures must be accompanied by the
82 * On the stable branches after KBI freeze, conditions must not be
83 * violated. Typically new fields are moved to the end of the
87 _Static_assert(offsetof(struct thread, td_flags) == 0xfc,
88 "struct thread KBI td_flags");
89 _Static_assert(offsetof(struct thread, td_pflags) == 0x104,
90 "struct thread KBI td_pflags");
91 _Static_assert(offsetof(struct thread, td_frame) == 0x4a0,
92 "struct thread KBI td_frame");
93 _Static_assert(offsetof(struct thread, td_emuldata) == 0x6b0,
94 "struct thread KBI td_emuldata");
95 _Static_assert(offsetof(struct proc, p_flag) == 0xb8,
96 "struct proc KBI p_flag");
97 _Static_assert(offsetof(struct proc, p_pid) == 0xc4,
98 "struct proc KBI p_pid");
99 _Static_assert(offsetof(struct proc, p_filemon) == 0x3c0,
100 "struct proc KBI p_filemon");
101 _Static_assert(offsetof(struct proc, p_comm) == 0x3d8,
102 "struct proc KBI p_comm");
103 _Static_assert(offsetof(struct proc, p_emuldata) == 0x4b8,
104 "struct proc KBI p_emuldata");
107 _Static_assert(offsetof(struct thread, td_flags) == 0x98,
108 "struct thread KBI td_flags");
109 _Static_assert(offsetof(struct thread, td_pflags) == 0xa0,
110 "struct thread KBI td_pflags");
111 _Static_assert(offsetof(struct thread, td_frame) == 0x300,
112 "struct thread KBI td_frame");
113 _Static_assert(offsetof(struct thread, td_emuldata) == 0x344,
114 "struct thread KBI td_emuldata");
115 _Static_assert(offsetof(struct proc, p_flag) == 0x6c,
116 "struct proc KBI p_flag");
117 _Static_assert(offsetof(struct proc, p_pid) == 0x78,
118 "struct proc KBI p_pid");
119 _Static_assert(offsetof(struct proc, p_filemon) == 0x26c,
120 "struct proc KBI p_filemon");
121 _Static_assert(offsetof(struct proc, p_comm) == 0x280,
122 "struct proc KBI p_comm");
123 _Static_assert(offsetof(struct proc, p_emuldata) == 0x30c,
124 "struct proc KBI p_emuldata");
127 SDT_PROVIDER_DECLARE(proc);
128 SDT_PROBE_DEFINE(proc, , , lwp__exit);
131 * thread related storage.
133 static uma_zone_t thread_zone;
135 struct thread_domain_data {
136 struct thread *tdd_zombies;
138 } __aligned(CACHE_LINE_SIZE);
140 static struct thread_domain_data thread_domain_data[MAXMEMDOM];
142 static struct task thread_reap_task;
143 static struct callout thread_reap_callout;
145 static void thread_zombie(struct thread *);
146 static void thread_reap_all(void);
147 static void thread_reap_task_cb(void *, int);
148 static void thread_reap_callout_cb(void *);
149 static int thread_unsuspend_one(struct thread *td, struct proc *p,
151 static void thread_free_batched(struct thread *td);
153 static __exclusive_cache_line struct mtx tid_lock;
154 static bitstr_t *tid_bitmap;
156 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash");
158 static int maxthread;
159 SYSCTL_INT(_kern, OID_AUTO, maxthread, CTLFLAG_RDTUN,
160 &maxthread, 0, "Maximum number of threads");
162 static __exclusive_cache_line int nthreads;
164 static LIST_HEAD(tidhashhead, thread) *tidhashtbl;
165 static u_long tidhash;
166 static u_long tidhashlock;
167 static struct rwlock *tidhashtbl_lock;
168 #define TIDHASH(tid) (&tidhashtbl[(tid) & tidhash])
169 #define TIDHASHLOCK(tid) (&tidhashtbl_lock[(tid) & tidhashlock])
171 EVENTHANDLER_LIST_DEFINE(thread_ctor);
172 EVENTHANDLER_LIST_DEFINE(thread_dtor);
173 EVENTHANDLER_LIST_DEFINE(thread_init);
174 EVENTHANDLER_LIST_DEFINE(thread_fini);
177 thread_count_inc_try(void)
181 nthreads_new = atomic_fetchadd_int(&nthreads, 1) + 1;
182 if (nthreads_new >= maxthread - 100) {
183 if (priv_check_cred(curthread->td_ucred, PRIV_MAXPROC) != 0 ||
184 nthreads_new >= maxthread) {
185 atomic_subtract_int(&nthreads, 1);
193 thread_count_inc(void)
195 static struct timeval lastfail;
199 if (thread_count_inc_try()) {
204 if (thread_count_inc_try()) {
208 if (ppsratecheck(&lastfail, &curfail, 1)) {
209 printf("maxthread limit exceeded by uid %u "
210 "(pid %d); consider increasing kern.maxthread\n",
211 curthread->td_ucred->cr_ruid, curproc->p_pid);
217 thread_count_sub(int n)
220 atomic_subtract_int(&nthreads, n);
224 thread_count_dec(void)
233 static lwpid_t trytid;
238 * It is an invariant that the bitmap is big enough to hold maxthread
239 * IDs. If we got to this point there has to be at least one free.
241 if (trytid >= maxthread)
243 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid);
245 KASSERT(trytid != 0, ("unexpectedly ran out of IDs"));
247 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid);
248 KASSERT(tid != -1, ("unexpectedly ran out of IDs"));
250 bit_set(tid_bitmap, tid);
252 mtx_unlock(&tid_lock);
253 return (tid + NO_PID);
257 tid_free_locked(lwpid_t rtid)
261 mtx_assert(&tid_lock, MA_OWNED);
262 KASSERT(rtid >= NO_PID,
263 ("%s: invalid tid %d\n", __func__, rtid));
265 KASSERT(bit_test(tid_bitmap, tid) != 0,
266 ("thread ID %d not allocated\n", rtid));
267 bit_clear(tid_bitmap, tid);
271 tid_free(lwpid_t rtid)
275 tid_free_locked(rtid);
276 mtx_unlock(&tid_lock);
280 tid_free_batch(lwpid_t *batch, int n)
285 for (i = 0; i < n; i++) {
286 tid_free_locked(batch[i]);
288 mtx_unlock(&tid_lock);
292 * Batching for thread reapping.
300 tidbatch_prep(struct tidbatch *tb)
307 tidbatch_add(struct tidbatch *tb, struct thread *td)
310 KASSERT(tb->n < nitems(tb->tab),
311 ("%s: count too high %d", __func__, tb->n));
312 tb->tab[tb->n] = td->td_tid;
317 tidbatch_process(struct tidbatch *tb)
320 KASSERT(tb->n <= nitems(tb->tab),
321 ("%s: count too high %d", __func__, tb->n));
322 if (tb->n == nitems(tb->tab)) {
323 tid_free_batch(tb->tab, tb->n);
329 tidbatch_final(struct tidbatch *tb)
332 KASSERT(tb->n <= nitems(tb->tab),
333 ("%s: count too high %d", __func__, tb->n));
335 tid_free_batch(tb->tab, tb->n);
340 * Prepare a thread for use.
343 thread_ctor(void *mem, int size, void *arg, int flags)
347 td = (struct thread *)mem;
348 td->td_state = TDS_INACTIVE;
349 td->td_lastcpu = td->td_oncpu = NOCPU;
350 td->td_allocdomain = vm_phys_domain(vtophys(td));
353 * Note that td_critnest begins life as 1 because the thread is not
354 * running and is thereby implicitly waiting to be on the receiving
355 * end of a context switch.
358 td->td_lend_user_pri = PRI_MAX;
360 audit_thread_alloc(td);
363 kdtrace_thread_ctor(td);
365 umtx_thread_alloc(td);
366 MPASS(td->td_sel == NULL);
371 * Reclaim a thread after use.
374 thread_dtor(void *mem, int size, void *arg)
378 td = (struct thread *)mem;
381 /* Verify that this thread is in a safe state to free. */
382 switch (td->td_state) {
388 * We must never unlink a thread that is in one of
389 * these states, because it is currently active.
391 panic("bad state for thread unlinking");
396 panic("bad thread state");
401 audit_thread_free(td);
404 kdtrace_thread_dtor(td);
406 /* Free all OSD associated to this thread. */
408 td_softdep_cleanup(td);
409 MPASS(td->td_su == NULL);
414 * Initialize type-stable parts of a thread (when newly created).
417 thread_init(void *mem, int size, int flags)
421 td = (struct thread *)mem;
423 td->td_sleepqueue = sleepq_alloc();
424 td->td_turnstile = turnstile_alloc();
426 EVENTHANDLER_DIRECT_INVOKE(thread_init, td);
427 umtx_thread_init(td);
434 * Tear down type-stable parts of a thread (just before being discarded).
437 thread_fini(void *mem, int size)
441 td = (struct thread *)mem;
442 EVENTHANDLER_DIRECT_INVOKE(thread_fini, td);
443 rlqentry_free(td->td_rlqe);
444 turnstile_free(td->td_turnstile);
445 sleepq_free(td->td_sleepqueue);
446 umtx_thread_fini(td);
447 MPASS(td->td_sel == NULL);
451 * For a newly created process,
452 * link up all the structures and its initial threads etc.
454 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc.
455 * proc_dtor() (should go away)
459 proc_linkup0(struct proc *p, struct thread *td)
461 TAILQ_INIT(&p->p_threads); /* all threads in proc */
466 proc_linkup(struct proc *p, struct thread *td)
469 sigqueue_init(&p->p_sigqueue, p);
470 p->p_ksi = ksiginfo_alloc(1);
471 if (p->p_ksi != NULL) {
472 /* XXX p_ksi may be null if ksiginfo zone is not ready */
473 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS;
475 LIST_INIT(&p->p_mqnotifier);
480 extern int max_threads_per_proc;
483 * Initialize global thread allocation resources.
493 * Place an upper limit on threads which can be allocated.
495 * Note that other factors may make the de facto limit much lower.
497 * Platform limits are somewhat arbitrary but deemed "more than good
498 * enough" for the foreseable future.
500 if (maxthread == 0) {
502 maxthread = MIN(maxproc * max_threads_per_proc, 1000000);
504 maxthread = MIN(maxproc * max_threads_per_proc, 100000);
508 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
509 tid_bitmap = bit_alloc(maxthread, M_TIDHASH, M_WAITOK);
515 if (tid0 != THREAD0_TID)
516 panic("tid0 %d != %d\n", tid0, THREAD0_TID);
518 flags = UMA_ZONE_NOFREE;
521 * Force thread structures to be allocated from the direct map.
522 * Otherwise, superpage promotions and demotions may temporarily
523 * invalidate thread structure mappings. For most dynamically allocated
524 * structures this is not a problem, but translation faults cannot be
525 * handled without accessing curthread.
527 flags |= UMA_ZONE_CONTIG;
529 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
530 thread_ctor, thread_dtor, thread_init, thread_fini,
532 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash);
533 tidhashlock = (tidhash + 1) / 64;
536 tidhashtbl_lock = malloc(sizeof(*tidhashtbl_lock) * (tidhashlock + 1),
537 M_TIDHASH, M_WAITOK | M_ZERO);
538 for (i = 0; i < tidhashlock + 1; i++)
539 rw_init(&tidhashtbl_lock[i], "tidhash");
541 TASK_INIT(&thread_reap_task, 0, thread_reap_task_cb, NULL);
542 callout_init(&thread_reap_callout, 1);
543 callout_reset(&thread_reap_callout, 5 * hz, thread_reap_callout_cb, NULL);
547 * Place an unused thread on the zombie list.
550 thread_zombie(struct thread *td)
552 struct thread_domain_data *tdd;
555 tdd = &thread_domain_data[td->td_allocdomain];
556 ztd = atomic_load_ptr(&tdd->tdd_zombies);
559 if (atomic_fcmpset_rel_ptr((uintptr_t *)&tdd->tdd_zombies,
560 (uintptr_t *)&ztd, (uintptr_t)td))
567 * Release a thread that has exited after cpu_throw().
570 thread_stash(struct thread *td)
572 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1);
577 * Reap zombies from passed domain.
580 thread_reap_domain(struct thread_domain_data *tdd)
582 struct thread *itd, *ntd;
583 struct tidbatch tidbatch;
584 struct credbatch credbatch;
590 * Reading upfront is pessimal if followed by concurrent atomic_swap,
591 * but most of the time the list is empty.
593 if (tdd->tdd_zombies == NULL)
596 itd = (struct thread *)atomic_swap_ptr((uintptr_t *)&tdd->tdd_zombies,
602 * Multiple CPUs can get here, the race is fine as ticks is only
605 tdd->tdd_reapticks = ticks;
607 tidbatch_prep(&tidbatch);
608 credbatch_prep(&credbatch);
613 while (itd != NULL) {
614 ntd = itd->td_zombie;
615 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, itd);
616 tidbatch_add(&tidbatch, itd);
617 credbatch_add(&credbatch, itd);
618 MPASS(itd->td_limit != NULL);
619 if (lim != itd->td_limit) {
621 lim_freen(lim, limcount);
627 thread_free_batched(itd);
628 tidbatch_process(&tidbatch);
629 credbatch_process(&credbatch);
632 thread_count_sub(tdcount);
638 tidbatch_final(&tidbatch);
639 credbatch_final(&credbatch);
641 thread_count_sub(tdcount);
643 MPASS(limcount != 0);
644 lim_freen(lim, limcount);
648 * Reap zombies from all domains.
651 thread_reap_all(void)
653 struct thread_domain_data *tdd;
656 domain = PCPU_GET(domain);
657 for (i = 0; i < vm_ndomains; i++) {
658 tdd = &thread_domain_data[(i + domain) % vm_ndomains];
659 thread_reap_domain(tdd);
664 * Reap zombies from local domain.
669 struct thread_domain_data *tdd;
672 domain = PCPU_GET(domain);
673 tdd = &thread_domain_data[domain];
675 thread_reap_domain(tdd);
679 thread_reap_task_cb(void *arg __unused, int pending __unused)
686 thread_reap_callout_cb(void *arg __unused)
688 struct thread_domain_data *tdd;
689 int i, cticks, lticks;
693 cticks = atomic_load_int(&ticks);
694 for (i = 0; i < vm_ndomains; i++) {
695 tdd = &thread_domain_data[i];
696 lticks = tdd->tdd_reapticks;
697 if (tdd->tdd_zombies != NULL &&
698 (u_int)(cticks - lticks) > 5 * hz) {
705 taskqueue_enqueue(taskqueue_thread, &thread_reap_task);
706 callout_reset(&thread_reap_callout, 5 * hz, thread_reap_callout_cb, NULL);
713 thread_alloc(int pages)
718 if (!thread_count_inc()) {
723 td = uma_zalloc(thread_zone, M_WAITOK);
724 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
725 if (!vm_thread_new(td, pages)) {
726 uma_zfree(thread_zone, td);
732 cpu_thread_alloc(td);
733 EVENTHANDLER_DIRECT_INVOKE(thread_ctor, td);
738 thread_alloc_stack(struct thread *td, int pages)
741 KASSERT(td->td_kstack == 0,
742 ("thread_alloc_stack called on a thread with kstack"));
743 if (!vm_thread_new(td, pages))
745 cpu_thread_alloc(td);
750 * Deallocate a thread.
753 thread_free_batched(struct thread *td)
756 lock_profile_thread_exit(td);
758 cpuset_rel(td->td_cpuset);
759 td->td_cpuset = NULL;
761 if (td->td_kstack != 0)
762 vm_thread_dispose(td);
763 callout_drain(&td->td_slpcallout);
765 * Freeing handled by the caller.
768 uma_zfree(thread_zone, td);
772 thread_free(struct thread *td)
776 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, td);
778 thread_free_batched(td);
784 thread_cow_get_proc(struct thread *newtd, struct proc *p)
787 PROC_LOCK_ASSERT(p, MA_OWNED);
788 newtd->td_realucred = crcowget(p->p_ucred);
789 newtd->td_ucred = newtd->td_realucred;
790 newtd->td_limit = lim_hold(p->p_limit);
791 newtd->td_cowgen = p->p_cowgen;
795 thread_cow_get(struct thread *newtd, struct thread *td)
798 MPASS(td->td_realucred == td->td_ucred);
799 newtd->td_realucred = crcowget(td->td_realucred);
800 newtd->td_ucred = newtd->td_realucred;
801 newtd->td_limit = lim_hold(td->td_limit);
802 newtd->td_cowgen = td->td_cowgen;
806 thread_cow_free(struct thread *td)
809 if (td->td_realucred != NULL)
811 if (td->td_limit != NULL)
812 lim_free(td->td_limit);
816 thread_cow_update(struct thread *td)
819 struct ucred *oldcred;
820 struct plimit *oldlimit;
825 oldcred = crcowsync();
826 if (td->td_limit != p->p_limit) {
827 oldlimit = td->td_limit;
828 td->td_limit = lim_hold(p->p_limit);
830 td->td_cowgen = p->p_cowgen;
834 if (oldlimit != NULL)
839 * Discard the current thread and exit from its context.
840 * Always called with scheduler locked.
842 * Because we can't free a thread while we're operating under its context,
843 * push the current thread into our CPU's deadthread holder. This means
844 * we needn't worry about someone else grabbing our context before we
850 uint64_t runtime, new_switchtime;
859 PROC_SLOCK_ASSERT(p, MA_OWNED);
860 mtx_assert(&Giant, MA_NOTOWNED);
862 PROC_LOCK_ASSERT(p, MA_OWNED);
863 KASSERT(p != NULL, ("thread exiting without a process"));
864 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
865 (long)p->p_pid, td->td_name);
866 SDT_PROBE0(proc, , , lwp__exit);
867 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
868 MPASS(td->td_realucred == td->td_ucred);
871 * drop FPU & debug register state storage, or any other
872 * architecture specific resources that
873 * would not be on a new untouched process.
878 * The last thread is left attached to the process
879 * So that the whole bundle gets recycled. Skip
880 * all this stuff if we never had threads.
881 * EXIT clears all sign of other threads when
882 * it goes to single threading, so the last thread always
883 * takes the short path.
885 if (p->p_flag & P_HADTHREADS) {
886 if (p->p_numthreads > 1) {
887 atomic_add_int(&td->td_proc->p_exitthreads, 1);
889 td2 = FIRST_THREAD_IN_PROC(p);
890 sched_exit_thread(td2, td);
893 * The test below is NOT true if we are the
894 * sole exiting thread. P_STOPPED_SINGLE is unset
895 * in exit1() after it is the only survivor.
897 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
898 if (p->p_numthreads == p->p_suspcount) {
899 thread_lock(p->p_singlethread);
900 wakeup_swapper = thread_unsuspend_one(
901 p->p_singlethread, p, false);
907 PCPU_SET(deadthread, td);
910 * The last thread is exiting.. but not through exit()
912 panic ("thread_exit: Last thread exiting on its own");
917 * If this thread is part of a process that is being tracked by hwpmc(4),
918 * inform the module of the thread's impending exit.
920 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) {
921 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
922 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT, NULL);
923 } else if (PMC_SYSTEM_SAMPLING_ACTIVE())
924 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL);
931 /* Do the same timestamp bookkeeping that mi_switch() would do. */
932 new_switchtime = cpu_ticks();
933 runtime = new_switchtime - PCPU_GET(switchtime);
934 td->td_runtime += runtime;
935 td->td_incruntime += runtime;
936 PCPU_SET(switchtime, new_switchtime);
937 PCPU_SET(switchticks, ticks);
940 /* Save our resource usage in our process. */
941 td->td_ru.ru_nvcsw++;
942 ruxagg_locked(p, td);
943 rucollect(&p->p_ru, &td->td_ru);
946 td->td_state = TDS_INACTIVE;
948 witness_thread_exit(td);
950 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
952 panic("I'm a teapot!");
957 * Do any thread specific cleanups that may be needed in wait()
958 * called with Giant, proc and schedlock not held.
961 thread_wait(struct proc *p)
965 mtx_assert(&Giant, MA_NOTOWNED);
966 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()"));
967 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking"));
968 td = FIRST_THREAD_IN_PROC(p);
969 /* Lock the last thread so we spin until it exits cpu_throw(). */
972 lock_profile_thread_exit(td);
973 cpuset_rel(td->td_cpuset);
974 td->td_cpuset = NULL;
975 cpu_thread_clean(td);
977 callout_drain(&td->td_slpcallout);
978 thread_reap(); /* check for zombie threads etc. */
982 * Link a thread to a process.
983 * set up anything that needs to be initialized for it to
984 * be used by the process.
987 thread_link(struct thread *td, struct proc *p)
991 * XXX This can't be enabled because it's called for proc0 before
992 * its lock has been created.
993 * PROC_LOCK_ASSERT(p, MA_OWNED);
995 td->td_state = TDS_INACTIVE;
997 td->td_flags = TDF_INMEM;
999 LIST_INIT(&td->td_contested);
1000 LIST_INIT(&td->td_lprof[0]);
1001 LIST_INIT(&td->td_lprof[1]);
1003 SLIST_INIT(&td->td_epochs);
1005 sigqueue_init(&td->td_sigqueue, p);
1006 callout_init(&td->td_slpcallout, 1);
1007 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist);
1016 thread_unlink(struct thread *td)
1018 struct proc *p = td->td_proc;
1020 PROC_LOCK_ASSERT(p, MA_OWNED);
1022 MPASS(SLIST_EMPTY(&td->td_epochs));
1025 TAILQ_REMOVE(&p->p_threads, td, td_plist);
1027 /* could clear a few other things here */
1028 /* Must NOT clear links to proc! */
1032 calc_remaining(struct proc *p, int mode)
1036 PROC_LOCK_ASSERT(p, MA_OWNED);
1037 PROC_SLOCK_ASSERT(p, MA_OWNED);
1038 if (mode == SINGLE_EXIT)
1039 remaining = p->p_numthreads;
1040 else if (mode == SINGLE_BOUNDARY)
1041 remaining = p->p_numthreads - p->p_boundary_count;
1042 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC)
1043 remaining = p->p_numthreads - p->p_suspcount;
1045 panic("calc_remaining: wrong mode %d", mode);
1050 remain_for_mode(int mode)
1053 return (mode == SINGLE_ALLPROC ? 0 : 1);
1057 weed_inhib(int mode, struct thread *td2, struct proc *p)
1061 PROC_LOCK_ASSERT(p, MA_OWNED);
1062 PROC_SLOCK_ASSERT(p, MA_OWNED);
1063 THREAD_LOCK_ASSERT(td2, MA_OWNED);
1068 * Since the thread lock is dropped by the scheduler we have
1069 * to retry to check for races.
1074 if (TD_IS_SUSPENDED(td2)) {
1075 wakeup_swapper |= thread_unsuspend_one(td2, p, true);
1079 if (TD_CAN_ABORT(td2)) {
1080 wakeup_swapper |= sleepq_abort(td2, EINTR);
1081 return (wakeup_swapper);
1084 case SINGLE_BOUNDARY:
1085 case SINGLE_NO_EXIT:
1086 if (TD_IS_SUSPENDED(td2) &&
1087 (td2->td_flags & TDF_BOUNDARY) == 0) {
1088 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
1092 if (TD_CAN_ABORT(td2)) {
1093 wakeup_swapper |= sleepq_abort(td2, ERESTART);
1094 return (wakeup_swapper);
1097 case SINGLE_ALLPROC:
1099 * ALLPROC suspend tries to avoid spurious EINTR for
1100 * threads sleeping interruptable, by suspending the
1101 * thread directly, similarly to sig_suspend_threads().
1102 * Since such sleep is not performed at the user
1103 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP
1104 * is used to avoid immediate un-suspend.
1106 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY |
1107 TDF_ALLPROCSUSP)) == 0) {
1108 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
1112 if (TD_CAN_ABORT(td2)) {
1113 if ((td2->td_flags & TDF_SBDRY) == 0) {
1114 thread_suspend_one(td2);
1115 td2->td_flags |= TDF_ALLPROCSUSP;
1117 wakeup_swapper |= sleepq_abort(td2, ERESTART);
1118 return (wakeup_swapper);
1126 return (wakeup_swapper);
1130 * Enforce single-threading.
1132 * Returns 1 if the caller must abort (another thread is waiting to
1133 * exit the process or similar). Process is locked!
1134 * Returns 0 when you are successfully the only thread running.
1135 * A process has successfully single threaded in the suspend mode when
1136 * There are no threads in user mode. Threads in the kernel must be
1137 * allowed to continue until they get to the user boundary. They may even
1138 * copy out their return values and data before suspending. They may however be
1139 * accelerated in reaching the user boundary as we will wake up
1140 * any sleeping threads that are interruptable. (PCATCH).
1143 thread_single(struct proc *p, int mode)
1147 int remaining, wakeup_swapper;
1150 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
1151 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
1152 ("invalid mode %d", mode));
1154 * If allowing non-ALLPROC singlethreading for non-curproc
1155 * callers, calc_remaining() and remain_for_mode() should be
1156 * adjusted to also account for td->td_proc != p. For now
1157 * this is not implemented because it is not used.
1159 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) ||
1160 (mode != SINGLE_ALLPROC && td->td_proc == p),
1161 ("mode %d proc %p curproc %p", mode, p, td->td_proc));
1162 mtx_assert(&Giant, MA_NOTOWNED);
1163 PROC_LOCK_ASSERT(p, MA_OWNED);
1165 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC)
1168 /* Is someone already single threading? */
1169 if (p->p_singlethread != NULL && p->p_singlethread != td)
1172 if (mode == SINGLE_EXIT) {
1173 p->p_flag |= P_SINGLE_EXIT;
1174 p->p_flag &= ~P_SINGLE_BOUNDARY;
1176 p->p_flag &= ~P_SINGLE_EXIT;
1177 if (mode == SINGLE_BOUNDARY)
1178 p->p_flag |= P_SINGLE_BOUNDARY;
1180 p->p_flag &= ~P_SINGLE_BOUNDARY;
1182 if (mode == SINGLE_ALLPROC)
1183 p->p_flag |= P_TOTAL_STOP;
1184 p->p_flag |= P_STOPPED_SINGLE;
1186 p->p_singlethread = td;
1187 remaining = calc_remaining(p, mode);
1188 while (remaining != remain_for_mode(mode)) {
1189 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE)
1192 FOREACH_THREAD_IN_PROC(p, td2) {
1196 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK;
1197 if (TD_IS_INHIBITED(td2)) {
1198 wakeup_swapper |= weed_inhib(mode, td2, p);
1200 } else if (TD_IS_RUNNING(td2) && td != td2) {
1201 forward_signal(td2);
1209 remaining = calc_remaining(p, mode);
1212 * Maybe we suspended some threads.. was it enough?
1214 if (remaining == remain_for_mode(mode))
1219 * Wake us up when everyone else has suspended.
1220 * In the mean time we suspend as well.
1222 thread_suspend_switch(td, p);
1223 remaining = calc_remaining(p, mode);
1225 if (mode == SINGLE_EXIT) {
1227 * Convert the process to an unthreaded process. The
1228 * SINGLE_EXIT is called by exit1() or execve(), in
1229 * both cases other threads must be retired.
1231 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads"));
1232 p->p_singlethread = NULL;
1233 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS);
1236 * Wait for any remaining threads to exit cpu_throw().
1238 while (p->p_exitthreads != 0) {
1241 sched_relinquish(td);
1245 } else if (mode == SINGLE_BOUNDARY) {
1247 * Wait until all suspended threads are removed from
1248 * the processors. The thread_suspend_check()
1249 * increments p_boundary_count while it is still
1250 * running, which makes it possible for the execve()
1251 * to destroy vmspace while our other threads are
1252 * still using the address space.
1254 * We lock the thread, which is only allowed to
1255 * succeed after context switch code finished using
1256 * the address space.
1258 FOREACH_THREAD_IN_PROC(p, td2) {
1262 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0,
1263 ("td %p not on boundary", td2));
1264 KASSERT(TD_IS_SUSPENDED(td2),
1265 ("td %p is not suspended", td2));
1274 thread_suspend_check_needed(void)
1281 PROC_LOCK_ASSERT(p, MA_OWNED);
1282 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 &&
1283 (td->td_dbgflags & TDB_SUSPEND) != 0));
1287 * Called in from locations that can safely check to see
1288 * whether we have to suspend or at least throttle for a
1289 * single-thread event (e.g. fork).
1291 * Such locations include userret().
1292 * If the "return_instead" argument is non zero, the thread must be able to
1293 * accept 0 (caller may continue), or 1 (caller must abort) as a result.
1295 * The 'return_instead' argument tells the function if it may do a
1296 * thread_exit() or suspend, or whether the caller must abort and back
1299 * If the thread that set the single_threading request has set the
1300 * P_SINGLE_EXIT bit in the process flags then this call will never return
1301 * if 'return_instead' is false, but will exit.
1303 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0
1304 *---------------+--------------------+---------------------
1305 * 0 | returns 0 | returns 0 or 1
1306 * | when ST ends | immediately
1307 *---------------+--------------------+---------------------
1308 * 1 | thread exits | returns 1
1310 * 0 = thread_exit() or suspension ok,
1311 * other = return error instead of stopping the thread.
1313 * While a full suspension is under effect, even a single threading
1314 * thread would be suspended if it made this call (but it shouldn't).
1315 * This call should only be made from places where
1316 * thread_exit() would be safe as that may be the outcome unless
1317 * return_instead is set.
1320 thread_suspend_check(int return_instead)
1328 mtx_assert(&Giant, MA_NOTOWNED);
1329 PROC_LOCK_ASSERT(p, MA_OWNED);
1330 while (thread_suspend_check_needed()) {
1331 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
1332 KASSERT(p->p_singlethread != NULL,
1333 ("singlethread not set"));
1335 * The only suspension in action is a
1336 * single-threading. Single threader need not stop.
1337 * It is safe to access p->p_singlethread unlocked
1338 * because it can only be set to our address by us.
1340 if (p->p_singlethread == td)
1341 return (0); /* Exempt from stopping. */
1343 if ((p->p_flag & P_SINGLE_EXIT) && return_instead)
1346 /* Should we goto user boundary if we didn't come from there? */
1347 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
1348 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
1352 * Ignore suspend requests if they are deferred.
1354 if ((td->td_flags & TDF_SBDRY) != 0) {
1355 KASSERT(return_instead,
1356 ("TDF_SBDRY set for unsafe thread_suspend_check"));
1357 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) !=
1358 (TDF_SEINTR | TDF_SERESTART),
1359 ("both TDF_SEINTR and TDF_SERESTART"));
1360 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0);
1364 * If the process is waiting for us to exit,
1365 * this thread should just suicide.
1366 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
1368 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
1372 * Allow Linux emulation layer to do some work
1373 * before thread suicide.
1375 if (__predict_false(p->p_sysent->sv_thread_detach != NULL))
1376 (p->p_sysent->sv_thread_detach)(td);
1377 umtx_thread_exit(td);
1379 panic("stopped thread did not exit");
1384 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
1385 if (p->p_numthreads == p->p_suspcount + 1) {
1386 thread_lock(p->p_singlethread);
1387 wakeup_swapper = thread_unsuspend_one(
1388 p->p_singlethread, p, false);
1396 * When a thread suspends, it just
1397 * gets taken off all queues.
1399 thread_suspend_one(td);
1400 if (return_instead == 0) {
1401 p->p_boundary_count++;
1402 td->td_flags |= TDF_BOUNDARY;
1405 mi_switch(SW_INVOL | SWT_SUSPEND);
1412 * Check for possible stops and suspensions while executing a
1413 * casueword or similar transiently failing operation.
1415 * The sleep argument controls whether the function can handle a stop
1416 * request itself or it should return ERESTART and the request is
1417 * proceed at the kernel/user boundary in ast.
1419 * Typically, when retrying due to casueword(9) failure (rv == 1), we
1420 * should handle the stop requests there, with exception of cases when
1421 * the thread owns a kernel resource, for instance busied the umtx
1422 * key, or when functions return immediately if thread_check_susp()
1423 * returned non-zero. On the other hand, retrying the whole lock
1424 * operation, we better not stop there but delegate the handling to
1427 * If the request is for thread termination P_SINGLE_EXIT, we cannot
1428 * handle it at all, and simply return EINTR.
1431 thread_check_susp(struct thread *td, bool sleep)
1437 * The check for TDF_NEEDSUSPCHK is racy, but it is enough to
1438 * eventually break the lockstep loop.
1440 if ((td->td_flags & TDF_NEEDSUSPCHK) == 0)
1445 if (p->p_flag & P_SINGLE_EXIT)
1447 else if (P_SHOULDSTOP(p) ||
1448 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND)))
1449 error = sleep ? thread_suspend_check(0) : ERESTART;
1455 thread_suspend_switch(struct thread *td, struct proc *p)
1458 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
1459 PROC_LOCK_ASSERT(p, MA_OWNED);
1460 PROC_SLOCK_ASSERT(p, MA_OWNED);
1462 * We implement thread_suspend_one in stages here to avoid
1463 * dropping the proc lock while the thread lock is owned.
1465 if (p == td->td_proc) {
1471 td->td_flags &= ~TDF_NEEDSUSPCHK;
1472 TD_SET_SUSPENDED(td);
1476 mi_switch(SW_VOL | SWT_SUSPEND);
1483 thread_suspend_one(struct thread *td)
1488 PROC_SLOCK_ASSERT(p, MA_OWNED);
1489 THREAD_LOCK_ASSERT(td, MA_OWNED);
1490 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
1492 td->td_flags &= ~TDF_NEEDSUSPCHK;
1493 TD_SET_SUSPENDED(td);
1498 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary)
1501 THREAD_LOCK_ASSERT(td, MA_OWNED);
1502 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
1503 TD_CLR_SUSPENDED(td);
1504 td->td_flags &= ~TDF_ALLPROCSUSP;
1505 if (td->td_proc == p) {
1506 PROC_SLOCK_ASSERT(p, MA_OWNED);
1508 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) {
1509 td->td_flags &= ~TDF_BOUNDARY;
1510 p->p_boundary_count--;
1513 return (setrunnable(td, 0));
1517 * Allow all threads blocked by single threading to continue running.
1520 thread_unsuspend(struct proc *p)
1525 PROC_LOCK_ASSERT(p, MA_OWNED);
1526 PROC_SLOCK_ASSERT(p, MA_OWNED);
1528 if (!P_SHOULDSTOP(p)) {
1529 FOREACH_THREAD_IN_PROC(p, td) {
1531 if (TD_IS_SUSPENDED(td)) {
1532 wakeup_swapper |= thread_unsuspend_one(td, p,
1537 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
1538 p->p_numthreads == p->p_suspcount) {
1540 * Stopping everything also did the job for the single
1541 * threading request. Now we've downgraded to single-threaded,
1544 if (p->p_singlethread->td_proc == p) {
1545 thread_lock(p->p_singlethread);
1546 wakeup_swapper = thread_unsuspend_one(
1547 p->p_singlethread, p, false);
1555 * End the single threading mode..
1558 thread_single_end(struct proc *p, int mode)
1563 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
1564 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
1565 ("invalid mode %d", mode));
1566 PROC_LOCK_ASSERT(p, MA_OWNED);
1567 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) ||
1568 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0),
1569 ("mode %d does not match P_TOTAL_STOP", mode));
1570 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread,
1571 ("thread_single_end from other thread %p %p",
1572 curthread, p->p_singlethread));
1573 KASSERT(mode != SINGLE_BOUNDARY ||
1574 (p->p_flag & P_SINGLE_BOUNDARY) != 0,
1575 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag));
1576 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY |
1579 p->p_singlethread = NULL;
1582 * If there are other threads they may now run,
1583 * unless of course there is a blanket 'stop order'
1584 * on the process. The single threader must be allowed
1585 * to continue however as this is a bad place to stop.
1587 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) {
1588 FOREACH_THREAD_IN_PROC(p, td) {
1590 if (TD_IS_SUSPENDED(td)) {
1591 wakeup_swapper |= thread_unsuspend_one(td, p,
1592 mode == SINGLE_BOUNDARY);
1597 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0,
1598 ("inconsistent boundary count %d", p->p_boundary_count));
1605 * Locate a thread by number and return with proc lock held.
1607 * thread exit establishes proc -> tidhash lock ordering, but lookup
1608 * takes tidhash first and needs to return locked proc.
1610 * The problem is worked around by relying on type-safety of both
1611 * structures and doing the work in 2 steps:
1612 * - tidhash-locked lookup which saves both thread and proc pointers
1613 * - proc-locked verification that the found thread still matches
1616 tdfind_hash(lwpid_t tid, pid_t pid, struct proc **pp, struct thread **tdp)
1618 #define RUN_THRESH 16
1625 rw_rlock(TIDHASHLOCK(tid));
1627 LIST_FOREACH(td, TIDHASH(tid), td_hash) {
1628 if (td->td_tid != tid) {
1633 if (pid != -1 && p->p_pid != pid) {
1637 if (run > RUN_THRESH) {
1638 if (rw_try_upgrade(TIDHASHLOCK(tid))) {
1639 LIST_REMOVE(td, td_hash);
1640 LIST_INSERT_HEAD(TIDHASH(td->td_tid),
1642 rw_wunlock(TIDHASHLOCK(tid));
1650 rw_runlock(TIDHASHLOCK(tid));
1659 tdfind(lwpid_t tid, pid_t pid)
1665 if (td->td_tid == tid) {
1666 if (pid != -1 && td->td_proc->p_pid != pid)
1668 PROC_LOCK(td->td_proc);
1673 if (!tdfind_hash(tid, pid, &p, &td))
1676 if (td->td_tid != tid) {
1680 if (td->td_proc != p) {
1684 if (p->p_state == PRS_NEW) {
1693 tidhash_add(struct thread *td)
1695 rw_wlock(TIDHASHLOCK(td->td_tid));
1696 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
1697 rw_wunlock(TIDHASHLOCK(td->td_tid));
1701 tidhash_remove(struct thread *td)
1704 rw_wlock(TIDHASHLOCK(td->td_tid));
1705 LIST_REMOVE(td, td_hash);
1706 rw_wunlock(TIDHASHLOCK(td->td_tid));