2 * Copyright (C) 2001 Julian Elischer <julian@freebsd.org>.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice(s), this list of conditions and the following disclaimer as
10 * the first lines of this file unmodified other than the possible
11 * addition of one or more copyright notices.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice(s), this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
17 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
20 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
22 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
23 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
29 #include "opt_witness.h"
30 #include "opt_hwpmc_hooks.h"
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/kernel.h>
39 #include <sys/mutex.h>
41 #include <sys/rangelock.h>
42 #include <sys/resourcevar.h>
45 #include <sys/sched.h>
46 #include <sys/sleepqueue.h>
47 #include <sys/selinfo.h>
48 #include <sys/syscallsubr.h>
49 #include <sys/sysent.h>
50 #include <sys/turnstile.h>
52 #include <sys/rwlock.h>
54 #include <sys/cpuset.h>
56 #include <sys/pmckern.h>
59 #include <security/audit/audit.h>
62 #include <vm/vm_extern.h>
64 #include <vm/vm_domain.h>
65 #include <sys/eventhandler.h>
67 SDT_PROVIDER_DECLARE(proc
);
68 SDT_PROBE_DEFINE(proc
, , , lwp__exit
);
71 * thread related storage.
73 static uma_zone_t thread_zone
;
75 TAILQ_HEAD(, thread
) zombie_threads
= TAILQ_HEAD_INITIALIZER(zombie_threads
);
76 static struct mtx zombie_lock
;
77 MTX_SYSINIT(zombie_lock
, &zombie_lock
, "zombie lock", MTX_SPIN
);
79 static void thread_zombie(struct thread
*);
80 static int thread_unsuspend_one(struct thread
*td
, struct proc
*p
,
83 #define TID_BUFFER_SIZE 1024
86 static struct unrhdr
*tid_unrhdr
;
87 static lwpid_t tid_buffer
[TID_BUFFER_SIZE
];
88 static int tid_head
, tid_tail
;
89 static MALLOC_DEFINE(M_TIDHASH
, "tidhash", "thread hash");
91 struct tidhashhead
*tidhashtbl
;
93 struct rwlock tidhash_lock
;
100 tid
= alloc_unr(tid_unrhdr
);
104 if (tid_head
== tid_tail
) {
105 mtx_unlock(&tid_lock
);
108 tid
= tid_buffer
[tid_head
];
109 tid_head
= (tid_head
+ 1) % TID_BUFFER_SIZE
;
110 mtx_unlock(&tid_lock
);
115 tid_free(lwpid_t tid
)
117 lwpid_t tmp_tid
= -1;
120 if ((tid_tail
+ 1) % TID_BUFFER_SIZE
== tid_head
) {
121 tmp_tid
= tid_buffer
[tid_head
];
122 tid_head
= (tid_head
+ 1) % TID_BUFFER_SIZE
;
124 tid_buffer
[tid_tail
] = tid
;
125 tid_tail
= (tid_tail
+ 1) % TID_BUFFER_SIZE
;
126 mtx_unlock(&tid_lock
);
128 free_unr(tid_unrhdr
, tmp_tid
);
132 * Prepare a thread for use.
135 thread_ctor(void *mem
, int size
, void *arg
, int flags
)
139 td
= (struct thread
*)mem
;
140 td
->td_state
= TDS_INACTIVE
;
141 td
->td_oncpu
= NOCPU
;
143 td
->td_tid
= tid_alloc();
146 * Note that td_critnest begins life as 1 because the thread is not
147 * running and is thereby implicitly waiting to be on the receiving
148 * end of a context switch.
151 td
->td_lend_user_pri
= PRI_MAX
;
152 EVENTHANDLER_INVOKE(thread_ctor
, td
);
154 audit_thread_alloc(td
);
156 umtx_thread_alloc(td
);
161 * Reclaim a thread after use.
164 thread_dtor(void *mem
, int size
, void *arg
)
168 td
= (struct thread
*)mem
;
171 /* Verify that this thread is in a safe state to free. */
172 switch (td
->td_state
) {
178 * We must never unlink a thread that is in one of
179 * these states, because it is currently active.
181 panic("bad state for thread unlinking");
186 panic("bad thread state");
191 audit_thread_free(td
);
193 /* Free all OSD associated to this thread. */
196 EVENTHANDLER_INVOKE(thread_dtor
, td
);
197 tid_free(td
->td_tid
);
201 * Initialize type-stable parts of a thread (when newly created).
204 thread_init(void *mem
, int size
, int flags
)
208 td
= (struct thread
*)mem
;
210 td
->td_sleepqueue
= sleepq_alloc();
211 td
->td_turnstile
= turnstile_alloc();
213 EVENTHANDLER_INVOKE(thread_init
, td
);
214 td
->td_sched
= (struct td_sched
*)&td
[1];
215 umtx_thread_init(td
);
222 * Tear down type-stable parts of a thread (just before being discarded).
225 thread_fini(void *mem
, int size
)
229 td
= (struct thread
*)mem
;
230 EVENTHANDLER_INVOKE(thread_fini
, td
);
231 rlqentry_free(td
->td_rlqe
);
232 turnstile_free(td
->td_turnstile
);
233 sleepq_free(td
->td_sleepqueue
);
234 umtx_thread_fini(td
);
239 * For a newly created process,
240 * link up all the structures and its initial threads etc.
242 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc.
243 * proc_dtor() (should go away)
247 proc_linkup0(struct proc
*p
, struct thread
*td
)
249 TAILQ_INIT(&p
->p_threads
); /* all threads in proc */
254 proc_linkup(struct proc
*p
, struct thread
*td
)
257 sigqueue_init(&p
->p_sigqueue
, p
);
258 p
->p_ksi
= ksiginfo_alloc(1);
259 if (p
->p_ksi
!= NULL
) {
260 /* XXX p_ksi may be null if ksiginfo zone is not ready */
261 p
->p_ksi
->ksi_flags
= KSI_EXT
| KSI_INS
;
263 LIST_INIT(&p
->p_mqnotifier
);
269 * Initialize global thread allocation resources.
275 mtx_init(&tid_lock
, "TID lock", NULL
, MTX_DEF
);
278 * pid_max cannot be greater than PID_MAX.
279 * leave one number for thread0.
281 tid_unrhdr
= new_unrhdr(PID_MAX
+ 2, INT_MAX
, &tid_lock
);
283 thread_zone
= uma_zcreate("THREAD", sched_sizeof_thread(),
284 thread_ctor
, thread_dtor
, thread_init
, thread_fini
,
285 16 - 1, UMA_ZONE_NOFREE
);
286 tidhashtbl
= hashinit(maxproc
/ 2, M_TIDHASH
, &tidhash
);
287 rw_init(&tidhash_lock
, "tidhash");
291 * Place an unused thread on the zombie list.
292 * Use the slpq as that must be unused by now.
295 thread_zombie(struct thread
*td
)
297 mtx_lock_spin(&zombie_lock
);
298 TAILQ_INSERT_HEAD(&zombie_threads
, td
, td_slpq
);
299 mtx_unlock_spin(&zombie_lock
);
303 * Release a thread that has exited after cpu_throw().
306 thread_stash(struct thread
*td
)
308 atomic_subtract_rel_int(&td
->td_proc
->p_exitthreads
, 1);
313 * Reap zombie resources.
318 struct thread
*td_first
, *td_next
;
321 * Don't even bother to lock if none at this instant,
322 * we really don't care about the next instant..
324 if (!TAILQ_EMPTY(&zombie_threads
)) {
325 mtx_lock_spin(&zombie_lock
);
326 td_first
= TAILQ_FIRST(&zombie_threads
);
328 TAILQ_INIT(&zombie_threads
);
329 mtx_unlock_spin(&zombie_lock
);
331 td_next
= TAILQ_NEXT(td_first
, td_slpq
);
332 thread_cow_free(td_first
);
333 thread_free(td_first
);
343 thread_alloc(int pages
)
347 thread_reap(); /* check if any zombies to get */
349 td
= (struct thread
*)uma_zalloc(thread_zone
, M_WAITOK
);
350 KASSERT(td
->td_kstack
== 0, ("thread_alloc got thread with kstack"));
351 if (!vm_thread_new(td
, pages
)) {
352 uma_zfree(thread_zone
, td
);
355 cpu_thread_alloc(td
);
356 vm_domain_policy_init(&td
->td_vm_dom_policy
);
361 thread_alloc_stack(struct thread
*td
, int pages
)
364 KASSERT(td
->td_kstack
== 0,
365 ("thread_alloc_stack called on a thread with kstack"));
366 if (!vm_thread_new(td
, pages
))
368 cpu_thread_alloc(td
);
373 * Deallocate a thread.
376 thread_free(struct thread
*td
)
379 lock_profile_thread_exit(td
);
381 cpuset_rel(td
->td_cpuset
);
382 td
->td_cpuset
= NULL
;
384 if (td
->td_kstack
!= 0)
385 vm_thread_dispose(td
);
386 vm_domain_policy_cleanup(&td
->td_vm_dom_policy
);
387 uma_zfree(thread_zone
, td
);
391 thread_cow_get_proc(struct thread
*newtd
, struct proc
*p
)
394 PROC_LOCK_ASSERT(p
, MA_OWNED
);
395 newtd
->td_ucred
= crhold(p
->p_ucred
);
396 newtd
->td_limit
= lim_hold(p
->p_limit
);
397 newtd
->td_cowgen
= p
->p_cowgen
;
401 thread_cow_get(struct thread
*newtd
, struct thread
*td
)
404 newtd
->td_ucred
= crhold(td
->td_ucred
);
405 newtd
->td_limit
= lim_hold(td
->td_limit
);
406 newtd
->td_cowgen
= td
->td_cowgen
;
410 thread_cow_free(struct thread
*td
)
413 if (td
->td_ucred
!= NULL
)
414 crfree(td
->td_ucred
);
415 if (td
->td_limit
!= NULL
)
416 lim_free(td
->td_limit
);
420 thread_cow_update(struct thread
*td
)
423 struct ucred
*oldcred
;
424 struct plimit
*oldlimit
;
430 if (td
->td_ucred
!= p
->p_ucred
) {
431 oldcred
= td
->td_ucred
;
432 td
->td_ucred
= crhold(p
->p_ucred
);
434 if (td
->td_limit
!= p
->p_limit
) {
435 oldlimit
= td
->td_limit
;
436 td
->td_limit
= lim_hold(p
->p_limit
);
438 td
->td_cowgen
= p
->p_cowgen
;
442 if (oldlimit
!= NULL
)
447 * Discard the current thread and exit from its context.
448 * Always called with scheduler locked.
450 * Because we can't free a thread while we're operating under its context,
451 * push the current thread into our CPU's deadthread holder. This means
452 * we needn't worry about someone else grabbing our context before we
458 uint64_t runtime
, new_switchtime
;
467 PROC_SLOCK_ASSERT(p
, MA_OWNED
);
468 mtx_assert(&Giant
, MA_NOTOWNED
);
470 PROC_LOCK_ASSERT(p
, MA_OWNED
);
471 KASSERT(p
!= NULL
, ("thread exiting without a process"));
472 CTR3(KTR_PROC
, "thread_exit: thread %p (pid %ld, %s)", td
,
473 (long)p
->p_pid
, td
->td_name
);
474 KASSERT(TAILQ_EMPTY(&td
->td_sigqueue
.sq_list
), ("signal pending"));
477 AUDIT_SYSCALL_EXIT(0, td
);
480 * drop FPU & debug register state storage, or any other
481 * architecture specific resources that
482 * would not be on a new untouched process.
484 cpu_thread_exit(td
); /* XXXSMP */
487 * The last thread is left attached to the process
488 * So that the whole bundle gets recycled. Skip
489 * all this stuff if we never had threads.
490 * EXIT clears all sign of other threads when
491 * it goes to single threading, so the last thread always
492 * takes the short path.
494 if (p
->p_flag
& P_HADTHREADS
) {
495 if (p
->p_numthreads
> 1) {
496 atomic_add_int(&td
->td_proc
->p_exitthreads
, 1);
498 td2
= FIRST_THREAD_IN_PROC(p
);
499 sched_exit_thread(td2
, td
);
502 * The test below is NOT true if we are the
503 * sole exiting thread. P_STOPPED_SINGLE is unset
504 * in exit1() after it is the only survivor.
506 if (P_SHOULDSTOP(p
) == P_STOPPED_SINGLE
) {
507 if (p
->p_numthreads
== p
->p_suspcount
) {
508 thread_lock(p
->p_singlethread
);
509 wakeup_swapper
= thread_unsuspend_one(
510 p
->p_singlethread
, p
, false);
511 thread_unlock(p
->p_singlethread
);
517 PCPU_SET(deadthread
, td
);
520 * The last thread is exiting.. but not through exit()
522 panic ("thread_exit: Last thread exiting on its own");
527 * If this thread is part of a process that is being tracked by hwpmc(4),
528 * inform the module of the thread's impending exit.
530 if (PMC_PROC_IS_USING_PMCS(td
->td_proc
))
531 PMC_SWITCH_CONTEXT(td
, PMC_FN_CSW_OUT
);
538 /* Do the same timestamp bookkeeping that mi_switch() would do. */
539 new_switchtime
= cpu_ticks();
540 runtime
= new_switchtime
- PCPU_GET(switchtime
);
541 td
->td_runtime
+= runtime
;
542 td
->td_incruntime
+= runtime
;
543 PCPU_SET(switchtime
, new_switchtime
);
544 PCPU_SET(switchticks
, ticks
);
545 PCPU_INC(cnt
.v_swtch
);
547 /* Save our resource usage in our process. */
548 td
->td_ru
.ru_nvcsw
++;
550 rucollect(&p
->p_ru
, &td
->td_ru
);
553 td
->td_state
= TDS_INACTIVE
;
555 witness_thread_exit(td
);
557 CTR1(KTR_PROC
, "thread_exit: cpu_throw() thread %p", td
);
559 panic("I'm a teapot!");
564 * Do any thread specific cleanups that may be needed in wait()
565 * called with Giant, proc and schedlock not held.
568 thread_wait(struct proc
*p
)
572 mtx_assert(&Giant
, MA_NOTOWNED
);
573 KASSERT(p
->p_numthreads
== 1, ("multiple threads in thread_wait()"));
574 KASSERT(p
->p_exitthreads
== 0, ("p_exitthreads leaking"));
575 td
= FIRST_THREAD_IN_PROC(p
);
576 /* Lock the last thread so we spin until it exits cpu_throw(). */
579 lock_profile_thread_exit(td
);
580 cpuset_rel(td
->td_cpuset
);
581 td
->td_cpuset
= NULL
;
582 cpu_thread_clean(td
);
584 thread_reap(); /* check for zombie threads etc. */
588 * Link a thread to a process.
589 * set up anything that needs to be initialized for it to
590 * be used by the process.
593 thread_link(struct thread
*td
, struct proc
*p
)
597 * XXX This can't be enabled because it's called for proc0 before
598 * its lock has been created.
599 * PROC_LOCK_ASSERT(p, MA_OWNED);
601 td
->td_state
= TDS_INACTIVE
;
603 td
->td_flags
= TDF_INMEM
;
605 LIST_INIT(&td
->td_contested
);
606 LIST_INIT(&td
->td_lprof
[0]);
607 LIST_INIT(&td
->td_lprof
[1]);
608 sigqueue_init(&td
->td_sigqueue
, p
);
609 callout_init(&td
->td_slpcallout
, 1);
610 TAILQ_INSERT_TAIL(&p
->p_threads
, td
, td_plist
);
619 thread_unlink(struct thread
*td
)
621 struct proc
*p
= td
->td_proc
;
623 PROC_LOCK_ASSERT(p
, MA_OWNED
);
624 TAILQ_REMOVE(&p
->p_threads
, td
, td_plist
);
626 /* could clear a few other things here */
627 /* Must NOT clear links to proc! */
631 calc_remaining(struct proc
*p
, int mode
)
635 PROC_LOCK_ASSERT(p
, MA_OWNED
);
636 PROC_SLOCK_ASSERT(p
, MA_OWNED
);
637 if (mode
== SINGLE_EXIT
)
638 remaining
= p
->p_numthreads
;
639 else if (mode
== SINGLE_BOUNDARY
)
640 remaining
= p
->p_numthreads
- p
->p_boundary_count
;
641 else if (mode
== SINGLE_NO_EXIT
|| mode
== SINGLE_ALLPROC
)
642 remaining
= p
->p_numthreads
- p
->p_suspcount
;
644 panic("calc_remaining: wrong mode %d", mode
);
649 remain_for_mode(int mode
)
652 return (mode
== SINGLE_ALLPROC
? 0 : 1);
656 weed_inhib(int mode
, struct thread
*td2
, struct proc
*p
)
660 PROC_LOCK_ASSERT(p
, MA_OWNED
);
661 PROC_SLOCK_ASSERT(p
, MA_OWNED
);
662 THREAD_LOCK_ASSERT(td2
, MA_OWNED
);
667 if (TD_IS_SUSPENDED(td2
))
668 wakeup_swapper
|= thread_unsuspend_one(td2
, p
, true);
669 if (TD_ON_SLEEPQ(td2
) && (td2
->td_flags
& TDF_SINTR
) != 0)
670 wakeup_swapper
|= sleepq_abort(td2
, EINTR
);
672 case SINGLE_BOUNDARY
:
673 if (TD_IS_SUSPENDED(td2
) && (td2
->td_flags
& TDF_BOUNDARY
) == 0)
674 wakeup_swapper
|= thread_unsuspend_one(td2
, p
, false);
675 if (TD_ON_SLEEPQ(td2
) && (td2
->td_flags
& TDF_SINTR
) != 0)
676 wakeup_swapper
|= sleepq_abort(td2
, ERESTART
);
679 if (TD_IS_SUSPENDED(td2
) && (td2
->td_flags
& TDF_BOUNDARY
) == 0)
680 wakeup_swapper
|= thread_unsuspend_one(td2
, p
, false);
681 if (TD_ON_SLEEPQ(td2
) && (td2
->td_flags
& TDF_SINTR
) != 0)
682 wakeup_swapper
|= sleepq_abort(td2
, ERESTART
);
686 * ALLPROC suspend tries to avoid spurious EINTR for
687 * threads sleeping interruptable, by suspending the
688 * thread directly, similarly to sig_suspend_threads().
689 * Since such sleep is not performed at the user
690 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP
691 * is used to avoid immediate un-suspend.
693 if (TD_IS_SUSPENDED(td2
) && (td2
->td_flags
& (TDF_BOUNDARY
|
694 TDF_ALLPROCSUSP
)) == 0)
695 wakeup_swapper
|= thread_unsuspend_one(td2
, p
, false);
696 if (TD_ON_SLEEPQ(td2
) && (td2
->td_flags
& TDF_SINTR
) != 0) {
697 if ((td2
->td_flags
& TDF_SBDRY
) == 0) {
698 thread_suspend_one(td2
);
699 td2
->td_flags
|= TDF_ALLPROCSUSP
;
701 wakeup_swapper
|= sleepq_abort(td2
, ERESTART
);
706 return (wakeup_swapper
);
710 * Enforce single-threading.
712 * Returns 1 if the caller must abort (another thread is waiting to
713 * exit the process or similar). Process is locked!
714 * Returns 0 when you are successfully the only thread running.
715 * A process has successfully single threaded in the suspend mode when
716 * There are no threads in user mode. Threads in the kernel must be
717 * allowed to continue until they get to the user boundary. They may even
718 * copy out their return values and data before suspending. They may however be
719 * accelerated in reaching the user boundary as we will wake up
720 * any sleeping threads that are interruptable. (PCATCH).
723 thread_single(struct proc
*p
, int mode
)
727 int remaining
, wakeup_swapper
;
730 KASSERT(mode
== SINGLE_EXIT
|| mode
== SINGLE_BOUNDARY
||
731 mode
== SINGLE_ALLPROC
|| mode
== SINGLE_NO_EXIT
,
732 ("invalid mode %d", mode
));
734 * If allowing non-ALLPROC singlethreading for non-curproc
735 * callers, calc_remaining() and remain_for_mode() should be
736 * adjusted to also account for td->td_proc != p. For now
737 * this is not implemented because it is not used.
739 KASSERT((mode
== SINGLE_ALLPROC
&& td
->td_proc
!= p
) ||
740 (mode
!= SINGLE_ALLPROC
&& td
->td_proc
== p
),
741 ("mode %d proc %p curproc %p", mode
, p
, td
->td_proc
));
742 mtx_assert(&Giant
, MA_NOTOWNED
);
743 PROC_LOCK_ASSERT(p
, MA_OWNED
);
745 if ((p
->p_flag
& P_HADTHREADS
) == 0 && mode
!= SINGLE_ALLPROC
)
748 /* Is someone already single threading? */
749 if (p
->p_singlethread
!= NULL
&& p
->p_singlethread
!= td
)
752 if (mode
== SINGLE_EXIT
) {
753 p
->p_flag
|= P_SINGLE_EXIT
;
754 p
->p_flag
&= ~P_SINGLE_BOUNDARY
;
756 p
->p_flag
&= ~P_SINGLE_EXIT
;
757 if (mode
== SINGLE_BOUNDARY
)
758 p
->p_flag
|= P_SINGLE_BOUNDARY
;
760 p
->p_flag
&= ~P_SINGLE_BOUNDARY
;
762 if (mode
== SINGLE_ALLPROC
)
763 p
->p_flag
|= P_TOTAL_STOP
;
764 p
->p_flag
|= P_STOPPED_SINGLE
;
766 p
->p_singlethread
= td
;
767 remaining
= calc_remaining(p
, mode
);
768 while (remaining
!= remain_for_mode(mode
)) {
769 if (P_SHOULDSTOP(p
) != P_STOPPED_SINGLE
)
772 FOREACH_THREAD_IN_PROC(p
, td2
) {
776 td2
->td_flags
|= TDF_ASTPENDING
| TDF_NEEDSUSPCHK
;
777 if (TD_IS_INHIBITED(td2
)) {
778 wakeup_swapper
|= weed_inhib(mode
, td2
, p
);
780 } else if (TD_IS_RUNNING(td2
) && td
!= td2
) {
788 remaining
= calc_remaining(p
, mode
);
791 * Maybe we suspended some threads.. was it enough?
793 if (remaining
== remain_for_mode(mode
))
798 * Wake us up when everyone else has suspended.
799 * In the mean time we suspend as well.
801 thread_suspend_switch(td
, p
);
802 remaining
= calc_remaining(p
, mode
);
804 if (mode
== SINGLE_EXIT
) {
806 * Convert the process to an unthreaded process. The
807 * SINGLE_EXIT is called by exit1() or execve(), in
808 * both cases other threads must be retired.
810 KASSERT(p
->p_numthreads
== 1, ("Unthreading with >1 threads"));
811 p
->p_singlethread
= NULL
;
812 p
->p_flag
&= ~(P_STOPPED_SINGLE
| P_SINGLE_EXIT
| P_HADTHREADS
);
815 * Wait for any remaining threads to exit cpu_throw().
817 while (p
->p_exitthreads
!= 0) {
820 sched_relinquish(td
);
824 } else if (mode
== SINGLE_BOUNDARY
) {
826 * Wait until all suspended threads are removed from
827 * the processors. The thread_suspend_check()
828 * increments p_boundary_count while it is still
829 * running, which makes it possible for the execve()
830 * to destroy vmspace while our other threads are
831 * still using the address space.
833 * We lock the thread, which is only allowed to
834 * succeed after context switch code finished using
837 FOREACH_THREAD_IN_PROC(p
, td2
) {
841 KASSERT((td2
->td_flags
& TDF_BOUNDARY
) != 0,
842 ("td %p not on boundary", td2
));
843 KASSERT(TD_IS_SUSPENDED(td2
),
844 ("td %p is not suspended", td2
));
853 thread_suspend_check_needed(void)
860 PROC_LOCK_ASSERT(p
, MA_OWNED
);
861 return (P_SHOULDSTOP(p
) || ((p
->p_flag
& P_TRACED
) != 0 &&
862 (td
->td_dbgflags
& TDB_SUSPEND
) != 0));
866 * Called in from locations that can safely check to see
867 * whether we have to suspend or at least throttle for a
868 * single-thread event (e.g. fork).
870 * Such locations include userret().
871 * If the "return_instead" argument is non zero, the thread must be able to
872 * accept 0 (caller may continue), or 1 (caller must abort) as a result.
874 * The 'return_instead' argument tells the function if it may do a
875 * thread_exit() or suspend, or whether the caller must abort and back
878 * If the thread that set the single_threading request has set the
879 * P_SINGLE_EXIT bit in the process flags then this call will never return
880 * if 'return_instead' is false, but will exit.
882 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0
883 *---------------+--------------------+---------------------
884 * 0 | returns 0 | returns 0 or 1
885 * | when ST ends | immediately
886 *---------------+--------------------+---------------------
887 * 1 | thread exits | returns 1
889 * 0 = thread_exit() or suspension ok,
890 * other = return error instead of stopping the thread.
892 * While a full suspension is under effect, even a single threading
893 * thread would be suspended if it made this call (but it shouldn't).
894 * This call should only be made from places where
895 * thread_exit() would be safe as that may be the outcome unless
896 * return_instead is set.
899 thread_suspend_check(int return_instead
)
907 mtx_assert(&Giant
, MA_NOTOWNED
);
908 PROC_LOCK_ASSERT(p
, MA_OWNED
);
909 while (thread_suspend_check_needed()) {
910 if (P_SHOULDSTOP(p
) == P_STOPPED_SINGLE
) {
911 KASSERT(p
->p_singlethread
!= NULL
,
912 ("singlethread not set"));
914 * The only suspension in action is a
915 * single-threading. Single threader need not stop.
916 * XXX Should be safe to access unlocked
917 * as it can only be set to be true by us.
919 if (p
->p_singlethread
== td
)
920 return (0); /* Exempt from stopping. */
922 if ((p
->p_flag
& P_SINGLE_EXIT
) && return_instead
)
925 /* Should we goto user boundary if we didn't come from there? */
926 if (P_SHOULDSTOP(p
) == P_STOPPED_SINGLE
&&
927 (p
->p_flag
& P_SINGLE_BOUNDARY
) && return_instead
)
931 * Ignore suspend requests if they are deferred.
933 if ((td
->td_flags
& TDF_SBDRY
) != 0) {
934 KASSERT(return_instead
,
935 ("TDF_SBDRY set for unsafe thread_suspend_check"));
940 * If the process is waiting for us to exit,
941 * this thread should just suicide.
942 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
944 if ((p
->p_flag
& P_SINGLE_EXIT
) && (p
->p_singlethread
!= td
)) {
948 * Allow Linux emulation layer to do some work
949 * before thread suicide.
951 if (__predict_false(p
->p_sysent
->sv_thread_detach
!= NULL
))
952 (p
->p_sysent
->sv_thread_detach
)(td
);
954 panic("stopped thread did not exit");
959 if (P_SHOULDSTOP(p
) == P_STOPPED_SINGLE
) {
960 if (p
->p_numthreads
== p
->p_suspcount
+ 1) {
961 thread_lock(p
->p_singlethread
);
962 wakeup_swapper
= thread_unsuspend_one(
963 p
->p_singlethread
, p
, false);
964 thread_unlock(p
->p_singlethread
);
972 * When a thread suspends, it just
973 * gets taken off all queues.
975 thread_suspend_one(td
);
976 if (return_instead
== 0) {
977 p
->p_boundary_count
++;
978 td
->td_flags
|= TDF_BOUNDARY
;
981 mi_switch(SW_INVOL
| SWT_SUSPEND
, NULL
);
989 thread_suspend_switch(struct thread
*td
, struct proc
*p
)
992 KASSERT(!TD_IS_SUSPENDED(td
), ("already suspended"));
993 PROC_LOCK_ASSERT(p
, MA_OWNED
);
994 PROC_SLOCK_ASSERT(p
, MA_OWNED
);
996 * We implement thread_suspend_one in stages here to avoid
997 * dropping the proc lock while the thread lock is owned.
999 if (p
== td
->td_proc
) {
1005 td
->td_flags
&= ~TDF_NEEDSUSPCHK
;
1006 TD_SET_SUSPENDED(td
);
1010 mi_switch(SW_VOL
| SWT_SUSPEND
, NULL
);
1018 thread_suspend_one(struct thread
*td
)
1023 PROC_SLOCK_ASSERT(p
, MA_OWNED
);
1024 THREAD_LOCK_ASSERT(td
, MA_OWNED
);
1025 KASSERT(!TD_IS_SUSPENDED(td
), ("already suspended"));
1027 td
->td_flags
&= ~TDF_NEEDSUSPCHK
;
1028 TD_SET_SUSPENDED(td
);
1033 thread_unsuspend_one(struct thread
*td
, struct proc
*p
, bool boundary
)
1036 THREAD_LOCK_ASSERT(td
, MA_OWNED
);
1037 KASSERT(TD_IS_SUSPENDED(td
), ("Thread not suspended"));
1038 TD_CLR_SUSPENDED(td
);
1039 td
->td_flags
&= ~TDF_ALLPROCSUSP
;
1040 if (td
->td_proc
== p
) {
1041 PROC_SLOCK_ASSERT(p
, MA_OWNED
);
1043 if (boundary
&& (td
->td_flags
& TDF_BOUNDARY
) != 0) {
1044 td
->td_flags
&= ~TDF_BOUNDARY
;
1045 p
->p_boundary_count
--;
1048 return (setrunnable(td
));
1052 * Allow all threads blocked by single threading to continue running.
1055 thread_unsuspend(struct proc
*p
)
1060 PROC_LOCK_ASSERT(p
, MA_OWNED
);
1061 PROC_SLOCK_ASSERT(p
, MA_OWNED
);
1063 if (!P_SHOULDSTOP(p
)) {
1064 FOREACH_THREAD_IN_PROC(p
, td
) {
1066 if (TD_IS_SUSPENDED(td
)) {
1067 wakeup_swapper
|= thread_unsuspend_one(td
, p
,
1072 } else if (P_SHOULDSTOP(p
) == P_STOPPED_SINGLE
&&
1073 p
->p_numthreads
== p
->p_suspcount
) {
1075 * Stopping everything also did the job for the single
1076 * threading request. Now we've downgraded to single-threaded,
1079 if (p
->p_singlethread
->td_proc
== p
) {
1080 thread_lock(p
->p_singlethread
);
1081 wakeup_swapper
= thread_unsuspend_one(
1082 p
->p_singlethread
, p
, false);
1083 thread_unlock(p
->p_singlethread
);
1091 * End the single threading mode..
1094 thread_single_end(struct proc
*p
, int mode
)
1099 KASSERT(mode
== SINGLE_EXIT
|| mode
== SINGLE_BOUNDARY
||
1100 mode
== SINGLE_ALLPROC
|| mode
== SINGLE_NO_EXIT
,
1101 ("invalid mode %d", mode
));
1102 PROC_LOCK_ASSERT(p
, MA_OWNED
);
1103 KASSERT((mode
== SINGLE_ALLPROC
&& (p
->p_flag
& P_TOTAL_STOP
) != 0) ||
1104 (mode
!= SINGLE_ALLPROC
&& (p
->p_flag
& P_TOTAL_STOP
) == 0),
1105 ("mode %d does not match P_TOTAL_STOP", mode
));
1106 KASSERT(mode
== SINGLE_ALLPROC
|| p
->p_singlethread
== curthread
,
1107 ("thread_single_end from other thread %p %p",
1108 curthread
, p
->p_singlethread
));
1109 KASSERT(mode
!= SINGLE_BOUNDARY
||
1110 (p
->p_flag
& P_SINGLE_BOUNDARY
) != 0,
1111 ("mis-matched SINGLE_BOUNDARY flags %x", p
->p_flag
));
1112 p
->p_flag
&= ~(P_STOPPED_SINGLE
| P_SINGLE_EXIT
| P_SINGLE_BOUNDARY
|
1115 p
->p_singlethread
= NULL
;
1118 * If there are other threads they may now run,
1119 * unless of course there is a blanket 'stop order'
1120 * on the process. The single threader must be allowed
1121 * to continue however as this is a bad place to stop.
1123 if (p
->p_numthreads
!= remain_for_mode(mode
) && !P_SHOULDSTOP(p
)) {
1124 FOREACH_THREAD_IN_PROC(p
, td
) {
1126 if (TD_IS_SUSPENDED(td
)) {
1127 wakeup_swapper
|= thread_unsuspend_one(td
, p
,
1128 mode
== SINGLE_BOUNDARY
);
1133 KASSERT(mode
!= SINGLE_BOUNDARY
|| p
->p_boundary_count
== 0,
1134 ("inconsistent boundary count %d", p
->p_boundary_count
));
1141 thread_find(struct proc
*p
, lwpid_t tid
)
1145 PROC_LOCK_ASSERT(p
, MA_OWNED
);
1146 FOREACH_THREAD_IN_PROC(p
, td
) {
1147 if (td
->td_tid
== tid
)
1153 /* Locate a thread by number; return with proc lock held. */
1155 tdfind(lwpid_t tid
, pid_t pid
)
1157 #define RUN_THRESH 16
1161 rw_rlock(&tidhash_lock
);
1162 LIST_FOREACH(td
, TIDHASH(tid
), td_hash
) {
1163 if (td
->td_tid
== tid
) {
1164 if (pid
!= -1 && td
->td_proc
->p_pid
!= pid
) {
1168 PROC_LOCK(td
->td_proc
);
1169 if (td
->td_proc
->p_state
== PRS_NEW
) {
1170 PROC_UNLOCK(td
->td_proc
);
1174 if (run
> RUN_THRESH
) {
1175 if (rw_try_upgrade(&tidhash_lock
)) {
1176 LIST_REMOVE(td
, td_hash
);
1177 LIST_INSERT_HEAD(TIDHASH(td
->td_tid
),
1179 rw_wunlock(&tidhash_lock
);
1187 rw_runlock(&tidhash_lock
);
1192 tidhash_add(struct thread
*td
)
1194 rw_wlock(&tidhash_lock
);
1195 LIST_INSERT_HEAD(TIDHASH(td
->td_tid
), td
, td_hash
);
1196 rw_wunlock(&tidhash_lock
);
1200 tidhash_remove(struct thread
*td
)
1202 rw_wlock(&tidhash_lock
);
1203 LIST_REMOVE(td
, td_hash
);
1204 rw_wunlock(&tidhash_lock
);