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/sysent.h>
54 #include <sys/turnstile.h>
55 #include <sys/taskqueue.h>
57 #include <sys/rwlock.h>
59 #include <sys/vmmeter.h>
60 #include <sys/cpuset.h>
62 #include <sys/pmckern.h>
66 #include <security/audit/audit.h>
70 #include <vm/vm_extern.h>
72 #include <vm/vm_phys.h>
73 #include <sys/eventhandler.h>
76 * Asserts below verify the stability of struct thread and struct proc
77 * layout, as exposed by KBI to modules. On head, the KBI is allowed
78 * to drift, change to the structures must be accompanied by the
81 * On the stable branches after KBI freeze, conditions must not be
82 * violated. Typically new fields are moved to the end of the
86 _Static_assert(offsetof(struct thread, td_flags) == 0xfc,
87 "struct thread KBI td_flags");
88 _Static_assert(offsetof(struct thread, td_pflags) == 0x104,
89 "struct thread KBI td_pflags");
90 _Static_assert(offsetof(struct thread, td_frame) == 0x4a0,
91 "struct thread KBI td_frame");
92 _Static_assert(offsetof(struct thread, td_emuldata) == 0x6b0,
93 "struct thread KBI td_emuldata");
94 _Static_assert(offsetof(struct proc, p_flag) == 0xb8,
95 "struct proc KBI p_flag");
96 _Static_assert(offsetof(struct proc, p_pid) == 0xc4,
97 "struct proc KBI p_pid");
98 _Static_assert(offsetof(struct proc, p_filemon) == 0x3c0,
99 "struct proc KBI p_filemon");
100 _Static_assert(offsetof(struct proc, p_comm) == 0x3d8,
101 "struct proc KBI p_comm");
102 _Static_assert(offsetof(struct proc, p_emuldata) == 0x4b8,
103 "struct proc KBI p_emuldata");
106 _Static_assert(offsetof(struct thread, td_flags) == 0x98,
107 "struct thread KBI td_flags");
108 _Static_assert(offsetof(struct thread, td_pflags) == 0xa0,
109 "struct thread KBI td_pflags");
110 _Static_assert(offsetof(struct thread, td_frame) == 0x300,
111 "struct thread KBI td_frame");
112 _Static_assert(offsetof(struct thread, td_emuldata) == 0x344,
113 "struct thread KBI td_emuldata");
114 _Static_assert(offsetof(struct proc, p_flag) == 0x6c,
115 "struct proc KBI p_flag");
116 _Static_assert(offsetof(struct proc, p_pid) == 0x78,
117 "struct proc KBI p_pid");
118 _Static_assert(offsetof(struct proc, p_filemon) == 0x26c,
119 "struct proc KBI p_filemon");
120 _Static_assert(offsetof(struct proc, p_comm) == 0x280,
121 "struct proc KBI p_comm");
122 _Static_assert(offsetof(struct proc, p_emuldata) == 0x30c,
123 "struct proc KBI p_emuldata");
126 SDT_PROVIDER_DECLARE(proc);
127 SDT_PROBE_DEFINE(proc, , , lwp__exit);
130 * thread related storage.
132 static uma_zone_t thread_zone;
134 struct thread_domain_data {
135 struct thread *tdd_zombies;
137 } __aligned(CACHE_LINE_SIZE);
139 static struct thread_domain_data thread_domain_data[MAXMEMDOM];
141 static struct task thread_reap_task;
142 static struct callout thread_reap_callout;
144 static void thread_zombie(struct thread *);
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 * Prepare a thread for use.
342 thread_ctor(void *mem, int size, void *arg, int flags)
346 td = (struct thread *)mem;
347 td->td_state = TDS_INACTIVE;
348 td->td_lastcpu = td->td_oncpu = NOCPU;
351 * Note that td_critnest begins life as 1 because the thread is not
352 * running and is thereby implicitly waiting to be on the receiving
353 * end of a context switch.
356 td->td_lend_user_pri = PRI_MAX;
358 audit_thread_alloc(td);
360 umtx_thread_alloc(td);
361 MPASS(td->td_sel == NULL);
366 * Reclaim a thread after use.
369 thread_dtor(void *mem, int size, void *arg)
373 td = (struct thread *)mem;
376 /* Verify that this thread is in a safe state to free. */
377 switch (td->td_state) {
383 * We must never unlink a thread that is in one of
384 * these states, because it is currently active.
386 panic("bad state for thread unlinking");
391 panic("bad thread state");
396 audit_thread_free(td);
398 /* Free all OSD associated to this thread. */
400 td_softdep_cleanup(td);
401 MPASS(td->td_su == NULL);
406 * Initialize type-stable parts of a thread (when newly created).
409 thread_init(void *mem, int size, int flags)
413 td = (struct thread *)mem;
415 td->td_sleepqueue = sleepq_alloc();
416 td->td_turnstile = turnstile_alloc();
418 EVENTHANDLER_DIRECT_INVOKE(thread_init, td);
419 umtx_thread_init(td);
426 * Tear down type-stable parts of a thread (just before being discarded).
429 thread_fini(void *mem, int size)
433 td = (struct thread *)mem;
434 EVENTHANDLER_DIRECT_INVOKE(thread_fini, td);
435 rlqentry_free(td->td_rlqe);
436 turnstile_free(td->td_turnstile);
437 sleepq_free(td->td_sleepqueue);
438 umtx_thread_fini(td);
439 MPASS(td->td_sel == NULL);
443 * For a newly created process,
444 * link up all the structures and its initial threads etc.
446 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc.
447 * proc_dtor() (should go away)
451 proc_linkup0(struct proc *p, struct thread *td)
453 TAILQ_INIT(&p->p_threads); /* all threads in proc */
458 proc_linkup(struct proc *p, struct thread *td)
461 sigqueue_init(&p->p_sigqueue, p);
462 p->p_ksi = ksiginfo_alloc(1);
463 if (p->p_ksi != NULL) {
464 /* XXX p_ksi may be null if ksiginfo zone is not ready */
465 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS;
467 LIST_INIT(&p->p_mqnotifier);
472 extern int max_threads_per_proc;
475 * Initialize global thread allocation resources.
485 * Place an upper limit on threads which can be allocated.
487 * Note that other factors may make the de facto limit much lower.
489 * Platform limits are somewhat arbitrary but deemed "more than good
490 * enough" for the foreseable future.
492 if (maxthread == 0) {
494 maxthread = MIN(maxproc * max_threads_per_proc, 1000000);
496 maxthread = MIN(maxproc * max_threads_per_proc, 100000);
500 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
501 tid_bitmap = bit_alloc(maxthread, M_TIDHASH, M_WAITOK);
507 if (tid0 != THREAD0_TID)
508 panic("tid0 %d != %d\n", tid0, THREAD0_TID);
510 flags = UMA_ZONE_NOFREE;
513 * Force thread structures to be allocated from the direct map.
514 * Otherwise, superpage promotions and demotions may temporarily
515 * invalidate thread structure mappings. For most dynamically allocated
516 * structures this is not a problem, but translation faults cannot be
517 * handled without accessing curthread.
519 flags |= UMA_ZONE_CONTIG;
521 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
522 thread_ctor, thread_dtor, thread_init, thread_fini,
524 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash);
525 tidhashlock = (tidhash + 1) / 64;
528 tidhashtbl_lock = malloc(sizeof(*tidhashtbl_lock) * (tidhashlock + 1),
529 M_TIDHASH, M_WAITOK | M_ZERO);
530 for (i = 0; i < tidhashlock + 1; i++)
531 rw_init(&tidhashtbl_lock[i], "tidhash");
533 TASK_INIT(&thread_reap_task, 0, thread_reap_task_cb, NULL);
534 callout_init(&thread_reap_callout, 1);
535 callout_reset(&thread_reap_callout, 5 * hz, thread_reap_callout_cb, NULL);
539 * Place an unused thread on the zombie list.
542 thread_zombie(struct thread *td)
544 struct thread_domain_data *tdd;
547 tdd = &thread_domain_data[vm_phys_domain(vtophys(td))];
548 ztd = atomic_load_ptr(&tdd->tdd_zombies);
551 if (atomic_fcmpset_rel_ptr((uintptr_t *)&tdd->tdd_zombies,
552 (uintptr_t *)&ztd, (uintptr_t)td))
559 * Release a thread that has exited after cpu_throw().
562 thread_stash(struct thread *td)
564 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1);
569 * Reap zombies from passed domain.
572 thread_reap_domain(struct thread_domain_data *tdd)
574 struct thread *itd, *ntd;
575 struct tidbatch tidbatch;
576 struct credbatch credbatch;
582 * Reading upfront is pessimal if followed by concurrent atomic_swap,
583 * but most of the time the list is empty.
585 if (tdd->tdd_zombies == NULL)
588 itd = (struct thread *)atomic_swap_ptr((uintptr_t *)&tdd->tdd_zombies,
594 * Multiple CPUs can get here, the race is fine as ticks is only
597 tdd->tdd_reapticks = ticks;
599 tidbatch_prep(&tidbatch);
600 credbatch_prep(&credbatch);
605 while (itd != NULL) {
606 ntd = itd->td_zombie;
607 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, itd);
608 tidbatch_add(&tidbatch, itd);
609 credbatch_add(&credbatch, itd);
610 MPASS(itd->td_limit != NULL);
611 if (lim != itd->td_limit) {
613 lim_freen(lim, limcount);
619 thread_free_batched(itd);
620 tidbatch_process(&tidbatch);
621 credbatch_process(&credbatch);
624 thread_count_sub(tdcount);
630 tidbatch_final(&tidbatch);
631 credbatch_final(&credbatch);
633 thread_count_sub(tdcount);
635 MPASS(limcount != 0);
636 lim_freen(lim, limcount);
640 * Reap zombies from all domains.
643 thread_reap_all(void)
645 struct thread_domain_data *tdd;
648 domain = PCPU_GET(domain);
649 for (i = 0; i < vm_ndomains; i++) {
650 tdd = &thread_domain_data[(i + domain) % vm_ndomains];
651 thread_reap_domain(tdd);
656 * Reap zombies from local domain.
661 struct thread_domain_data *tdd;
664 domain = PCPU_GET(domain);
665 tdd = &thread_domain_data[domain];
667 thread_reap_domain(tdd);
671 thread_reap_task_cb(void *arg __unused, int pending __unused)
678 thread_reap_callout_cb(void *arg __unused)
680 struct thread_domain_data *tdd;
681 int i, cticks, lticks;
685 cticks = atomic_load_int(&ticks);
686 for (i = 0; i < vm_ndomains; i++) {
687 tdd = &thread_domain_data[i];
688 lticks = tdd->tdd_reapticks;
689 if (tdd->tdd_zombies != NULL &&
690 (u_int)(cticks - lticks) > 5 * hz) {
697 taskqueue_enqueue(taskqueue_thread, &thread_reap_task);
698 callout_reset(&thread_reap_callout, 5 * hz, thread_reap_callout_cb, NULL);
705 thread_alloc(int pages)
710 if (!thread_count_inc()) {
715 td = uma_zalloc(thread_zone, M_WAITOK);
716 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
717 if (!vm_thread_new(td, pages)) {
718 uma_zfree(thread_zone, td);
724 cpu_thread_alloc(td);
725 EVENTHANDLER_DIRECT_INVOKE(thread_ctor, td);
730 thread_alloc_stack(struct thread *td, int pages)
733 KASSERT(td->td_kstack == 0,
734 ("thread_alloc_stack called on a thread with kstack"));
735 if (!vm_thread_new(td, pages))
737 cpu_thread_alloc(td);
742 * Deallocate a thread.
745 thread_free_batched(struct thread *td)
748 lock_profile_thread_exit(td);
750 cpuset_rel(td->td_cpuset);
751 td->td_cpuset = NULL;
753 if (td->td_kstack != 0)
754 vm_thread_dispose(td);
755 callout_drain(&td->td_slpcallout);
757 * Freeing handled by the caller.
760 uma_zfree(thread_zone, td);
764 thread_free(struct thread *td)
768 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, td);
770 thread_free_batched(td);
776 thread_cow_get_proc(struct thread *newtd, struct proc *p)
779 PROC_LOCK_ASSERT(p, MA_OWNED);
780 newtd->td_realucred = crcowget(p->p_ucred);
781 newtd->td_ucred = newtd->td_realucred;
782 newtd->td_limit = lim_hold(p->p_limit);
783 newtd->td_cowgen = p->p_cowgen;
787 thread_cow_get(struct thread *newtd, struct thread *td)
790 MPASS(td->td_realucred == td->td_ucred);
791 newtd->td_realucred = crcowget(td->td_realucred);
792 newtd->td_ucred = newtd->td_realucred;
793 newtd->td_limit = lim_hold(td->td_limit);
794 newtd->td_cowgen = td->td_cowgen;
798 thread_cow_free(struct thread *td)
801 if (td->td_realucred != NULL)
803 if (td->td_limit != NULL)
804 lim_free(td->td_limit);
808 thread_cow_update(struct thread *td)
811 struct ucred *oldcred;
812 struct plimit *oldlimit;
817 oldcred = crcowsync();
818 if (td->td_limit != p->p_limit) {
819 oldlimit = td->td_limit;
820 td->td_limit = lim_hold(p->p_limit);
822 td->td_cowgen = p->p_cowgen;
826 if (oldlimit != NULL)
831 * Discard the current thread and exit from its context.
832 * Always called with scheduler locked.
834 * Because we can't free a thread while we're operating under its context,
835 * push the current thread into our CPU's deadthread holder. This means
836 * we needn't worry about someone else grabbing our context before we
842 uint64_t runtime, new_switchtime;
851 PROC_SLOCK_ASSERT(p, MA_OWNED);
852 mtx_assert(&Giant, MA_NOTOWNED);
854 PROC_LOCK_ASSERT(p, MA_OWNED);
855 KASSERT(p != NULL, ("thread exiting without a process"));
856 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
857 (long)p->p_pid, td->td_name);
858 SDT_PROBE0(proc, , , lwp__exit);
859 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
860 MPASS(td->td_realucred == td->td_ucred);
863 * drop FPU & debug register state storage, or any other
864 * architecture specific resources that
865 * would not be on a new untouched process.
870 * The last thread is left attached to the process
871 * So that the whole bundle gets recycled. Skip
872 * all this stuff if we never had threads.
873 * EXIT clears all sign of other threads when
874 * it goes to single threading, so the last thread always
875 * takes the short path.
877 if (p->p_flag & P_HADTHREADS) {
878 if (p->p_numthreads > 1) {
879 atomic_add_int(&td->td_proc->p_exitthreads, 1);
881 td2 = FIRST_THREAD_IN_PROC(p);
882 sched_exit_thread(td2, td);
885 * The test below is NOT true if we are the
886 * sole exiting thread. P_STOPPED_SINGLE is unset
887 * in exit1() after it is the only survivor.
889 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
890 if (p->p_numthreads == p->p_suspcount) {
891 thread_lock(p->p_singlethread);
892 wakeup_swapper = thread_unsuspend_one(
893 p->p_singlethread, p, false);
899 PCPU_SET(deadthread, td);
902 * The last thread is exiting.. but not through exit()
904 panic ("thread_exit: Last thread exiting on its own");
909 * If this thread is part of a process that is being tracked by hwpmc(4),
910 * inform the module of the thread's impending exit.
912 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) {
913 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
914 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT, NULL);
915 } else if (PMC_SYSTEM_SAMPLING_ACTIVE())
916 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL);
923 /* Do the same timestamp bookkeeping that mi_switch() would do. */
924 new_switchtime = cpu_ticks();
925 runtime = new_switchtime - PCPU_GET(switchtime);
926 td->td_runtime += runtime;
927 td->td_incruntime += runtime;
928 PCPU_SET(switchtime, new_switchtime);
929 PCPU_SET(switchticks, ticks);
932 /* Save our resource usage in our process. */
933 td->td_ru.ru_nvcsw++;
934 ruxagg_locked(p, td);
935 rucollect(&p->p_ru, &td->td_ru);
938 td->td_state = TDS_INACTIVE;
940 witness_thread_exit(td);
942 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
944 panic("I'm a teapot!");
949 * Do any thread specific cleanups that may be needed in wait()
950 * called with Giant, proc and schedlock not held.
953 thread_wait(struct proc *p)
957 mtx_assert(&Giant, MA_NOTOWNED);
958 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()"));
959 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking"));
960 td = FIRST_THREAD_IN_PROC(p);
961 /* Lock the last thread so we spin until it exits cpu_throw(). */
964 lock_profile_thread_exit(td);
965 cpuset_rel(td->td_cpuset);
966 td->td_cpuset = NULL;
967 cpu_thread_clean(td);
969 callout_drain(&td->td_slpcallout);
970 thread_reap(); /* check for zombie threads etc. */
974 * Link a thread to a process.
975 * set up anything that needs to be initialized for it to
976 * be used by the process.
979 thread_link(struct thread *td, struct proc *p)
983 * XXX This can't be enabled because it's called for proc0 before
984 * its lock has been created.
985 * PROC_LOCK_ASSERT(p, MA_OWNED);
987 td->td_state = TDS_INACTIVE;
989 td->td_flags = TDF_INMEM;
991 LIST_INIT(&td->td_contested);
992 LIST_INIT(&td->td_lprof[0]);
993 LIST_INIT(&td->td_lprof[1]);
995 SLIST_INIT(&td->td_epochs);
997 sigqueue_init(&td->td_sigqueue, p);
998 callout_init(&td->td_slpcallout, 1);
999 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist);
1008 thread_unlink(struct thread *td)
1010 struct proc *p = td->td_proc;
1012 PROC_LOCK_ASSERT(p, MA_OWNED);
1014 MPASS(SLIST_EMPTY(&td->td_epochs));
1017 TAILQ_REMOVE(&p->p_threads, td, td_plist);
1019 /* could clear a few other things here */
1020 /* Must NOT clear links to proc! */
1024 calc_remaining(struct proc *p, int mode)
1028 PROC_LOCK_ASSERT(p, MA_OWNED);
1029 PROC_SLOCK_ASSERT(p, MA_OWNED);
1030 if (mode == SINGLE_EXIT)
1031 remaining = p->p_numthreads;
1032 else if (mode == SINGLE_BOUNDARY)
1033 remaining = p->p_numthreads - p->p_boundary_count;
1034 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC)
1035 remaining = p->p_numthreads - p->p_suspcount;
1037 panic("calc_remaining: wrong mode %d", mode);
1042 remain_for_mode(int mode)
1045 return (mode == SINGLE_ALLPROC ? 0 : 1);
1049 weed_inhib(int mode, struct thread *td2, struct proc *p)
1053 PROC_LOCK_ASSERT(p, MA_OWNED);
1054 PROC_SLOCK_ASSERT(p, MA_OWNED);
1055 THREAD_LOCK_ASSERT(td2, MA_OWNED);
1060 * Since the thread lock is dropped by the scheduler we have
1061 * to retry to check for races.
1066 if (TD_IS_SUSPENDED(td2)) {
1067 wakeup_swapper |= thread_unsuspend_one(td2, p, true);
1071 if (TD_CAN_ABORT(td2)) {
1072 wakeup_swapper |= sleepq_abort(td2, EINTR);
1073 return (wakeup_swapper);
1076 case SINGLE_BOUNDARY:
1077 case SINGLE_NO_EXIT:
1078 if (TD_IS_SUSPENDED(td2) &&
1079 (td2->td_flags & TDF_BOUNDARY) == 0) {
1080 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
1084 if (TD_CAN_ABORT(td2)) {
1085 wakeup_swapper |= sleepq_abort(td2, ERESTART);
1086 return (wakeup_swapper);
1089 case SINGLE_ALLPROC:
1091 * ALLPROC suspend tries to avoid spurious EINTR for
1092 * threads sleeping interruptable, by suspending the
1093 * thread directly, similarly to sig_suspend_threads().
1094 * Since such sleep is not performed at the user
1095 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP
1096 * is used to avoid immediate un-suspend.
1098 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY |
1099 TDF_ALLPROCSUSP)) == 0) {
1100 wakeup_swapper |= thread_unsuspend_one(td2, p, false);
1104 if (TD_CAN_ABORT(td2)) {
1105 if ((td2->td_flags & TDF_SBDRY) == 0) {
1106 thread_suspend_one(td2);
1107 td2->td_flags |= TDF_ALLPROCSUSP;
1109 wakeup_swapper |= sleepq_abort(td2, ERESTART);
1110 return (wakeup_swapper);
1118 return (wakeup_swapper);
1122 * Enforce single-threading.
1124 * Returns 1 if the caller must abort (another thread is waiting to
1125 * exit the process or similar). Process is locked!
1126 * Returns 0 when you are successfully the only thread running.
1127 * A process has successfully single threaded in the suspend mode when
1128 * There are no threads in user mode. Threads in the kernel must be
1129 * allowed to continue until they get to the user boundary. They may even
1130 * copy out their return values and data before suspending. They may however be
1131 * accelerated in reaching the user boundary as we will wake up
1132 * any sleeping threads that are interruptable. (PCATCH).
1135 thread_single(struct proc *p, int mode)
1139 int remaining, wakeup_swapper;
1142 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
1143 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
1144 ("invalid mode %d", mode));
1146 * If allowing non-ALLPROC singlethreading for non-curproc
1147 * callers, calc_remaining() and remain_for_mode() should be
1148 * adjusted to also account for td->td_proc != p. For now
1149 * this is not implemented because it is not used.
1151 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) ||
1152 (mode != SINGLE_ALLPROC && td->td_proc == p),
1153 ("mode %d proc %p curproc %p", mode, p, td->td_proc));
1154 mtx_assert(&Giant, MA_NOTOWNED);
1155 PROC_LOCK_ASSERT(p, MA_OWNED);
1157 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC)
1160 /* Is someone already single threading? */
1161 if (p->p_singlethread != NULL && p->p_singlethread != td)
1164 if (mode == SINGLE_EXIT) {
1165 p->p_flag |= P_SINGLE_EXIT;
1166 p->p_flag &= ~P_SINGLE_BOUNDARY;
1168 p->p_flag &= ~P_SINGLE_EXIT;
1169 if (mode == SINGLE_BOUNDARY)
1170 p->p_flag |= P_SINGLE_BOUNDARY;
1172 p->p_flag &= ~P_SINGLE_BOUNDARY;
1174 if (mode == SINGLE_ALLPROC)
1175 p->p_flag |= P_TOTAL_STOP;
1176 p->p_flag |= P_STOPPED_SINGLE;
1178 p->p_singlethread = td;
1179 remaining = calc_remaining(p, mode);
1180 while (remaining != remain_for_mode(mode)) {
1181 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE)
1184 FOREACH_THREAD_IN_PROC(p, td2) {
1188 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK;
1189 if (TD_IS_INHIBITED(td2)) {
1190 wakeup_swapper |= weed_inhib(mode, td2, p);
1192 } else if (TD_IS_RUNNING(td2) && td != td2) {
1193 forward_signal(td2);
1201 remaining = calc_remaining(p, mode);
1204 * Maybe we suspended some threads.. was it enough?
1206 if (remaining == remain_for_mode(mode))
1211 * Wake us up when everyone else has suspended.
1212 * In the mean time we suspend as well.
1214 thread_suspend_switch(td, p);
1215 remaining = calc_remaining(p, mode);
1217 if (mode == SINGLE_EXIT) {
1219 * Convert the process to an unthreaded process. The
1220 * SINGLE_EXIT is called by exit1() or execve(), in
1221 * both cases other threads must be retired.
1223 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads"));
1224 p->p_singlethread = NULL;
1225 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS);
1228 * Wait for any remaining threads to exit cpu_throw().
1230 while (p->p_exitthreads != 0) {
1233 sched_relinquish(td);
1237 } else if (mode == SINGLE_BOUNDARY) {
1239 * Wait until all suspended threads are removed from
1240 * the processors. The thread_suspend_check()
1241 * increments p_boundary_count while it is still
1242 * running, which makes it possible for the execve()
1243 * to destroy vmspace while our other threads are
1244 * still using the address space.
1246 * We lock the thread, which is only allowed to
1247 * succeed after context switch code finished using
1248 * the address space.
1250 FOREACH_THREAD_IN_PROC(p, td2) {
1254 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0,
1255 ("td %p not on boundary", td2));
1256 KASSERT(TD_IS_SUSPENDED(td2),
1257 ("td %p is not suspended", td2));
1266 thread_suspend_check_needed(void)
1273 PROC_LOCK_ASSERT(p, MA_OWNED);
1274 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 &&
1275 (td->td_dbgflags & TDB_SUSPEND) != 0));
1279 * Called in from locations that can safely check to see
1280 * whether we have to suspend or at least throttle for a
1281 * single-thread event (e.g. fork).
1283 * Such locations include userret().
1284 * If the "return_instead" argument is non zero, the thread must be able to
1285 * accept 0 (caller may continue), or 1 (caller must abort) as a result.
1287 * The 'return_instead' argument tells the function if it may do a
1288 * thread_exit() or suspend, or whether the caller must abort and back
1291 * If the thread that set the single_threading request has set the
1292 * P_SINGLE_EXIT bit in the process flags then this call will never return
1293 * if 'return_instead' is false, but will exit.
1295 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0
1296 *---------------+--------------------+---------------------
1297 * 0 | returns 0 | returns 0 or 1
1298 * | when ST ends | immediately
1299 *---------------+--------------------+---------------------
1300 * 1 | thread exits | returns 1
1302 * 0 = thread_exit() or suspension ok,
1303 * other = return error instead of stopping the thread.
1305 * While a full suspension is under effect, even a single threading
1306 * thread would be suspended if it made this call (but it shouldn't).
1307 * This call should only be made from places where
1308 * thread_exit() would be safe as that may be the outcome unless
1309 * return_instead is set.
1312 thread_suspend_check(int return_instead)
1320 mtx_assert(&Giant, MA_NOTOWNED);
1321 PROC_LOCK_ASSERT(p, MA_OWNED);
1322 while (thread_suspend_check_needed()) {
1323 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
1324 KASSERT(p->p_singlethread != NULL,
1325 ("singlethread not set"));
1327 * The only suspension in action is a
1328 * single-threading. Single threader need not stop.
1329 * It is safe to access p->p_singlethread unlocked
1330 * because it can only be set to our address by us.
1332 if (p->p_singlethread == td)
1333 return (0); /* Exempt from stopping. */
1335 if ((p->p_flag & P_SINGLE_EXIT) && return_instead)
1338 /* Should we goto user boundary if we didn't come from there? */
1339 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
1340 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
1344 * Ignore suspend requests if they are deferred.
1346 if ((td->td_flags & TDF_SBDRY) != 0) {
1347 KASSERT(return_instead,
1348 ("TDF_SBDRY set for unsafe thread_suspend_check"));
1349 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) !=
1350 (TDF_SEINTR | TDF_SERESTART),
1351 ("both TDF_SEINTR and TDF_SERESTART"));
1352 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0);
1356 * If the process is waiting for us to exit,
1357 * this thread should just suicide.
1358 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
1360 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
1364 * Allow Linux emulation layer to do some work
1365 * before thread suicide.
1367 if (__predict_false(p->p_sysent->sv_thread_detach != NULL))
1368 (p->p_sysent->sv_thread_detach)(td);
1369 umtx_thread_exit(td);
1371 panic("stopped thread did not exit");
1376 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
1377 if (p->p_numthreads == p->p_suspcount + 1) {
1378 thread_lock(p->p_singlethread);
1379 wakeup_swapper = thread_unsuspend_one(
1380 p->p_singlethread, p, false);
1388 * When a thread suspends, it just
1389 * gets taken off all queues.
1391 thread_suspend_one(td);
1392 if (return_instead == 0) {
1393 p->p_boundary_count++;
1394 td->td_flags |= TDF_BOUNDARY;
1397 mi_switch(SW_INVOL | SWT_SUSPEND);
1404 * Check for possible stops and suspensions while executing a
1405 * casueword or similar transiently failing operation.
1407 * The sleep argument controls whether the function can handle a stop
1408 * request itself or it should return ERESTART and the request is
1409 * proceed at the kernel/user boundary in ast.
1411 * Typically, when retrying due to casueword(9) failure (rv == 1), we
1412 * should handle the stop requests there, with exception of cases when
1413 * the thread owns a kernel resource, for instance busied the umtx
1414 * key, or when functions return immediately if thread_check_susp()
1415 * returned non-zero. On the other hand, retrying the whole lock
1416 * operation, we better not stop there but delegate the handling to
1419 * If the request is for thread termination P_SINGLE_EXIT, we cannot
1420 * handle it at all, and simply return EINTR.
1423 thread_check_susp(struct thread *td, bool sleep)
1429 * The check for TDF_NEEDSUSPCHK is racy, but it is enough to
1430 * eventually break the lockstep loop.
1432 if ((td->td_flags & TDF_NEEDSUSPCHK) == 0)
1437 if (p->p_flag & P_SINGLE_EXIT)
1439 else if (P_SHOULDSTOP(p) ||
1440 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND)))
1441 error = sleep ? thread_suspend_check(0) : ERESTART;
1447 thread_suspend_switch(struct thread *td, struct proc *p)
1450 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
1451 PROC_LOCK_ASSERT(p, MA_OWNED);
1452 PROC_SLOCK_ASSERT(p, MA_OWNED);
1454 * We implement thread_suspend_one in stages here to avoid
1455 * dropping the proc lock while the thread lock is owned.
1457 if (p == td->td_proc) {
1463 td->td_flags &= ~TDF_NEEDSUSPCHK;
1464 TD_SET_SUSPENDED(td);
1468 mi_switch(SW_VOL | SWT_SUSPEND);
1475 thread_suspend_one(struct thread *td)
1480 PROC_SLOCK_ASSERT(p, MA_OWNED);
1481 THREAD_LOCK_ASSERT(td, MA_OWNED);
1482 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
1484 td->td_flags &= ~TDF_NEEDSUSPCHK;
1485 TD_SET_SUSPENDED(td);
1490 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary)
1493 THREAD_LOCK_ASSERT(td, MA_OWNED);
1494 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
1495 TD_CLR_SUSPENDED(td);
1496 td->td_flags &= ~TDF_ALLPROCSUSP;
1497 if (td->td_proc == p) {
1498 PROC_SLOCK_ASSERT(p, MA_OWNED);
1500 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) {
1501 td->td_flags &= ~TDF_BOUNDARY;
1502 p->p_boundary_count--;
1505 return (setrunnable(td, 0));
1509 * Allow all threads blocked by single threading to continue running.
1512 thread_unsuspend(struct proc *p)
1517 PROC_LOCK_ASSERT(p, MA_OWNED);
1518 PROC_SLOCK_ASSERT(p, MA_OWNED);
1520 if (!P_SHOULDSTOP(p)) {
1521 FOREACH_THREAD_IN_PROC(p, td) {
1523 if (TD_IS_SUSPENDED(td)) {
1524 wakeup_swapper |= thread_unsuspend_one(td, p,
1529 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
1530 p->p_numthreads == p->p_suspcount) {
1532 * Stopping everything also did the job for the single
1533 * threading request. Now we've downgraded to single-threaded,
1536 if (p->p_singlethread->td_proc == p) {
1537 thread_lock(p->p_singlethread);
1538 wakeup_swapper = thread_unsuspend_one(
1539 p->p_singlethread, p, false);
1547 * End the single threading mode..
1550 thread_single_end(struct proc *p, int mode)
1555 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY ||
1556 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT,
1557 ("invalid mode %d", mode));
1558 PROC_LOCK_ASSERT(p, MA_OWNED);
1559 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) ||
1560 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0),
1561 ("mode %d does not match P_TOTAL_STOP", mode));
1562 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread,
1563 ("thread_single_end from other thread %p %p",
1564 curthread, p->p_singlethread));
1565 KASSERT(mode != SINGLE_BOUNDARY ||
1566 (p->p_flag & P_SINGLE_BOUNDARY) != 0,
1567 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag));
1568 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY |
1571 p->p_singlethread = NULL;
1574 * If there are other threads they may now run,
1575 * unless of course there is a blanket 'stop order'
1576 * on the process. The single threader must be allowed
1577 * to continue however as this is a bad place to stop.
1579 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) {
1580 FOREACH_THREAD_IN_PROC(p, td) {
1582 if (TD_IS_SUSPENDED(td)) {
1583 wakeup_swapper |= thread_unsuspend_one(td, p,
1584 mode == SINGLE_BOUNDARY);
1589 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0,
1590 ("inconsistent boundary count %d", p->p_boundary_count));
1597 * Locate a thread by number and return with proc lock held.
1599 * thread exit establishes proc -> tidhash lock ordering, but lookup
1600 * takes tidhash first and needs to return locked proc.
1602 * The problem is worked around by relying on type-safety of both
1603 * structures and doing the work in 2 steps:
1604 * - tidhash-locked lookup which saves both thread and proc pointers
1605 * - proc-locked verification that the found thread still matches
1608 tdfind_hash(lwpid_t tid, pid_t pid, struct proc **pp, struct thread **tdp)
1610 #define RUN_THRESH 16
1617 rw_rlock(TIDHASHLOCK(tid));
1619 LIST_FOREACH(td, TIDHASH(tid), td_hash) {
1620 if (td->td_tid != tid) {
1625 if (pid != -1 && p->p_pid != pid) {
1629 if (run > RUN_THRESH) {
1630 if (rw_try_upgrade(TIDHASHLOCK(tid))) {
1631 LIST_REMOVE(td, td_hash);
1632 LIST_INSERT_HEAD(TIDHASH(td->td_tid),
1634 rw_wunlock(TIDHASHLOCK(tid));
1642 rw_runlock(TIDHASHLOCK(tid));
1651 tdfind(lwpid_t tid, pid_t pid)
1657 if (td->td_tid == tid) {
1658 if (pid != -1 && td->td_proc->p_pid != pid)
1660 PROC_LOCK(td->td_proc);
1665 if (!tdfind_hash(tid, pid, &p, &td))
1668 if (td->td_tid != tid) {
1672 if (td->td_proc != p) {
1676 if (p->p_state == PRS_NEW) {
1685 tidhash_add(struct thread *td)
1687 rw_wlock(TIDHASHLOCK(td->td_tid));
1688 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
1689 rw_wunlock(TIDHASHLOCK(td->td_tid));
1693 tidhash_remove(struct thread *td)
1696 rw_wlock(TIDHASHLOCK(td->td_tid));
1697 LIST_REMOVE(td, td_hash);
1698 rw_wunlock(TIDHASHLOCK(td->td_tid));