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/*-
* Copyright (C) 2001 Julian Elischer <julian@freebsd.org>.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice(s), this list of conditions and the following disclaimer as
* the first lines of this file unmodified other than the possible
* addition of one or more copyright notices.
* 2. Redistributions in binary form must reproduce the above copyright
* notice(s), this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*/
#include "opt_witness.h"
#include "opt_kdtrace.h"
#include "opt_hwpmc_hooks.h"
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/sys/kern/kern_thread.c 236344 2012-05-30 23:22:52Z rstone $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/sdt.h>
#include <sys/smp.h>
#include <sys/sched.h>
#include <sys/sleepqueue.h>
#include <sys/selinfo.h>
#include <sys/turnstile.h>
#include <sys/ktr.h>
#include <sys/rwlock.h>
#include <sys/umtx.h>
#include <sys/cpuset.h>
#ifdef HWPMC_HOOKS
#include <sys/pmckern.h>
#endif
#include <security/audit/audit.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/uma.h>
#include <sys/eventhandler.h>
SDT_PROVIDER_DECLARE(proc);
SDT_PROBE_DEFINE(proc, , , lwp_exit, lwp-exit);
/*
* thread related storage.
*/
static uma_zone_t thread_zone;
TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads);
static struct mtx zombie_lock;
MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN);
static void thread_zombie(struct thread *);
#define TID_BUFFER_SIZE 1024
struct mtx tid_lock;
static struct unrhdr *tid_unrhdr;
static lwpid_t tid_buffer[TID_BUFFER_SIZE];
static int tid_head, tid_tail;
static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash");
struct tidhashhead *tidhashtbl;
u_long tidhash;
struct rwlock tidhash_lock;
static lwpid_t
tid_alloc(void)
{
lwpid_t tid;
tid = alloc_unr(tid_unrhdr);
if (tid != -1)
return (tid);
mtx_lock(&tid_lock);
if (tid_head == tid_tail) {
mtx_unlock(&tid_lock);
return (-1);
}
tid = tid_buffer[tid_head++];
tid_head %= TID_BUFFER_SIZE;
mtx_unlock(&tid_lock);
return (tid);
}
static void
tid_free(lwpid_t tid)
{
lwpid_t tmp_tid = -1;
mtx_lock(&tid_lock);
if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) {
tmp_tid = tid_buffer[tid_head++];
tid_head = (tid_head + 1) % TID_BUFFER_SIZE;
}
tid_buffer[tid_tail++] = tid;
tid_tail %= TID_BUFFER_SIZE;
mtx_unlock(&tid_lock);
if (tmp_tid != -1)
free_unr(tid_unrhdr, tmp_tid);
}
/*
* Prepare a thread for use.
*/
static int
thread_ctor(void *mem, int size, void *arg, int flags)
{
struct thread *td;
td = (struct thread *)mem;
td->td_state = TDS_INACTIVE;
td->td_oncpu = NOCPU;
td->td_tid = tid_alloc();
/*
* Note that td_critnest begins life as 1 because the thread is not
* running and is thereby implicitly waiting to be on the receiving
* end of a context switch.
*/
td->td_critnest = 1;
td->td_lend_user_pri = PRI_MAX;
EVENTHANDLER_INVOKE(thread_ctor, td);
#ifdef AUDIT
audit_thread_alloc(td);
#endif
umtx_thread_alloc(td);
return (0);
}
/*
* Reclaim a thread after use.
*/
static void
thread_dtor(void *mem, int size, void *arg)
{
struct thread *td;
td = (struct thread *)mem;
#ifdef INVARIANTS
/* Verify that this thread is in a safe state to free. */
switch (td->td_state) {
case TDS_INHIBITED:
case TDS_RUNNING:
case TDS_CAN_RUN:
case TDS_RUNQ:
/*
* We must never unlink a thread that is in one of
* these states, because it is currently active.
*/
panic("bad state for thread unlinking");
/* NOTREACHED */
case TDS_INACTIVE:
break;
default:
panic("bad thread state");
/* NOTREACHED */
}
#endif
#ifdef AUDIT
audit_thread_free(td);
#endif
/* Free all OSD associated to this thread. */
osd_thread_exit(td);
EVENTHANDLER_INVOKE(thread_dtor, td);
tid_free(td->td_tid);
}
/*
* Initialize type-stable parts of a thread (when newly created).
*/
static int
thread_init(void *mem, int size, int flags)
{
struct thread *td;
td = (struct thread *)mem;
td->td_sleepqueue = sleepq_alloc();
td->td_turnstile = turnstile_alloc();
EVENTHANDLER_INVOKE(thread_init, td);
td->td_sched = (struct td_sched *)&td[1];
umtx_thread_init(td);
td->td_kstack = 0;
return (0);
}
/*
* Tear down type-stable parts of a thread (just before being discarded).
*/
static void
thread_fini(void *mem, int size)
{
struct thread *td;
td = (struct thread *)mem;
EVENTHANDLER_INVOKE(thread_fini, td);
turnstile_free(td->td_turnstile);
sleepq_free(td->td_sleepqueue);
umtx_thread_fini(td);
seltdfini(td);
}
/*
* For a newly created process,
* link up all the structures and its initial threads etc.
* called from:
* {arch}/{arch}/machdep.c ia64_init(), init386() etc.
* proc_dtor() (should go away)
* proc_init()
*/
void
proc_linkup0(struct proc *p, struct thread *td)
{
TAILQ_INIT(&p->p_threads); /* all threads in proc */
proc_linkup(p, td);
}
void
proc_linkup(struct proc *p, struct thread *td)
{
sigqueue_init(&p->p_sigqueue, p);
p->p_ksi = ksiginfo_alloc(1);
if (p->p_ksi != NULL) {
/* XXX p_ksi may be null if ksiginfo zone is not ready */
p->p_ksi->ksi_flags = KSI_EXT | KSI_INS;
}
LIST_INIT(&p->p_mqnotifier);
p->p_numthreads = 0;
thread_link(td, p);
}
/*
* Initialize global thread allocation resources.
*/
void
threadinit(void)
{
mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
/* leave one number for thread0 */
tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock);
thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
thread_ctor, thread_dtor, thread_init, thread_fini,
16 - 1, 0);
tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash);
rw_init(&tidhash_lock, "tidhash");
}
/*
* Place an unused thread on the zombie list.
* Use the slpq as that must be unused by now.
*/
void
thread_zombie(struct thread *td)
{
mtx_lock_spin(&zombie_lock);
TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq);
mtx_unlock_spin(&zombie_lock);
}
/*
* Release a thread that has exited after cpu_throw().
*/
void
thread_stash(struct thread *td)
{
atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1);
thread_zombie(td);
}
/*
* Reap zombie resources.
*/
void
thread_reap(void)
{
struct thread *td_first, *td_next;
/*
* Don't even bother to lock if none at this instant,
* we really don't care about the next instant..
*/
if (!TAILQ_EMPTY(&zombie_threads)) {
mtx_lock_spin(&zombie_lock);
td_first = TAILQ_FIRST(&zombie_threads);
if (td_first)
TAILQ_INIT(&zombie_threads);
mtx_unlock_spin(&zombie_lock);
while (td_first) {
td_next = TAILQ_NEXT(td_first, td_slpq);
if (td_first->td_ucred)
crfree(td_first->td_ucred);
thread_free(td_first);
td_first = td_next;
}
}
}
/*
* Allocate a thread.
*/
struct thread *
thread_alloc(int pages)
{
struct thread *td;
thread_reap(); /* check if any zombies to get */
td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK);
KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
if (!vm_thread_new(td, pages)) {
uma_zfree(thread_zone, td);
return (NULL);
}
cpu_thread_alloc(td);
return (td);
}
int
thread_alloc_stack(struct thread *td, int pages)
{
KASSERT(td->td_kstack == 0,
("thread_alloc_stack called on a thread with kstack"));
if (!vm_thread_new(td, pages))
return (0);
cpu_thread_alloc(td);
return (1);
}
/*
* Deallocate a thread.
*/
void
thread_free(struct thread *td)
{
lock_profile_thread_exit(td);
if (td->td_cpuset)
cpuset_rel(td->td_cpuset);
td->td_cpuset = NULL;
cpu_thread_free(td);
if (td->td_kstack != 0)
vm_thread_dispose(td);
uma_zfree(thread_zone, td);
}
/*
* Discard the current thread and exit from its context.
* Always called with scheduler locked.
*
* Because we can't free a thread while we're operating under its context,
* push the current thread into our CPU's deadthread holder. This means
* we needn't worry about someone else grabbing our context before we
* do a cpu_throw().
*/
void
thread_exit(void)
{
uint64_t runtime, new_switchtime;
struct thread *td;
struct thread *td2;
struct proc *p;
int wakeup_swapper;
td = curthread;
p = td->td_proc;
PROC_SLOCK_ASSERT(p, MA_OWNED);
mtx_assert(&Giant, MA_NOTOWNED);
PROC_LOCK_ASSERT(p, MA_OWNED);
KASSERT(p != NULL, ("thread exiting without a process"));
CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
(long)p->p_pid, td->td_name);
KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
#ifdef AUDIT
AUDIT_SYSCALL_EXIT(0, td);
#endif
umtx_thread_exit(td);
/*
* drop FPU & debug register state storage, or any other
* architecture specific resources that
* would not be on a new untouched process.
*/
cpu_thread_exit(td); /* XXXSMP */
/*
* The last thread is left attached to the process
* So that the whole bundle gets recycled. Skip
* all this stuff if we never had threads.
* EXIT clears all sign of other threads when
* it goes to single threading, so the last thread always
* takes the short path.
*/
if (p->p_flag & P_HADTHREADS) {
if (p->p_numthreads > 1) {
thread_unlink(td);
td2 = FIRST_THREAD_IN_PROC(p);
sched_exit_thread(td2, td);
/*
* The test below is NOT true if we are the
* sole exiting thread. P_STOPPED_SINGLE is unset
* in exit1() after it is the only survivor.
*/
if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
if (p->p_numthreads == p->p_suspcount) {
thread_lock(p->p_singlethread);
wakeup_swapper = thread_unsuspend_one(
p->p_singlethread);
thread_unlock(p->p_singlethread);
if (wakeup_swapper)
kick_proc0();
}
}
atomic_add_int(&td->td_proc->p_exitthreads, 1);
PCPU_SET(deadthread, td);
} else {
/*
* The last thread is exiting.. but not through exit()
*/
panic ("thread_exit: Last thread exiting on its own");
}
}
#ifdef HWPMC_HOOKS
/*
* If this thread is part of a process that is being tracked by hwpmc(4),
* inform the module of the thread's impending exit.
*/
if (PMC_PROC_IS_USING_PMCS(td->td_proc))
PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
#endif
PROC_UNLOCK(p);
/* Do the same timestamp bookkeeping that mi_switch() would do. */
new_switchtime = cpu_ticks();
runtime = new_switchtime - PCPU_GET(switchtime);
td->td_runtime += runtime;
td->td_incruntime += runtime;
PCPU_SET(switchtime, new_switchtime);
PCPU_SET(switchticks, ticks);
PCPU_INC(cnt.v_swtch);
/* Save our resource usage in our process. */
td->td_ru.ru_nvcsw++;
ruxagg(p, td);
rucollect(&p->p_ru, &td->td_ru);
thread_lock(td);
PROC_SUNLOCK(p);
td->td_state = TDS_INACTIVE;
#ifdef WITNESS
witness_thread_exit(td);
#endif
CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
sched_throw(td);
panic("I'm a teapot!");
/* NOTREACHED */
}
/*
* Do any thread specific cleanups that may be needed in wait()
* called with Giant, proc and schedlock not held.
*/
void
thread_wait(struct proc *p)
{
struct thread *td;
mtx_assert(&Giant, MA_NOTOWNED);
KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()"));
td = FIRST_THREAD_IN_PROC(p);
/* Lock the last thread so we spin until it exits cpu_throw(). */
thread_lock(td);
thread_unlock(td);
/* Wait for any remaining threads to exit cpu_throw(). */
while (p->p_exitthreads)
sched_relinquish(curthread);
lock_profile_thread_exit(td);
cpuset_rel(td->td_cpuset);
td->td_cpuset = NULL;
cpu_thread_clean(td);
crfree(td->td_ucred);
thread_reap(); /* check for zombie threads etc. */
}
/*
* Link a thread to a process.
* set up anything that needs to be initialized for it to
* be used by the process.
*/
void
thread_link(struct thread *td, struct proc *p)
{
/*
* XXX This can't be enabled because it's called for proc0 before
* its lock has been created.
* PROC_LOCK_ASSERT(p, MA_OWNED);
*/
td->td_state = TDS_INACTIVE;
td->td_proc = p;
td->td_flags = TDF_INMEM;
LIST_INIT(&td->td_contested);
LIST_INIT(&td->td_lprof[0]);
LIST_INIT(&td->td_lprof[1]);
sigqueue_init(&td->td_sigqueue, p);
callout_init(&td->td_slpcallout, CALLOUT_MPSAFE);
TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist);
p->p_numthreads++;
}
/*
* Convert a process with one thread to an unthreaded process.
*/
void
thread_unthread(struct thread *td)
{
struct proc *p = td->td_proc;
KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads"));
p->p_flag &= ~P_HADTHREADS;
}
/*
* Called from:
* thread_exit()
*/
void
thread_unlink(struct thread *td)
{
struct proc *p = td->td_proc;
PROC_LOCK_ASSERT(p, MA_OWNED);
TAILQ_REMOVE(&p->p_threads, td, td_plist);
p->p_numthreads--;
/* could clear a few other things here */
/* Must NOT clear links to proc! */
}
static int
calc_remaining(struct proc *p, int mode)
{
int remaining;
PROC_LOCK_ASSERT(p, MA_OWNED);
PROC_SLOCK_ASSERT(p, MA_OWNED);
if (mode == SINGLE_EXIT)
remaining = p->p_numthreads;
else if (mode == SINGLE_BOUNDARY)
remaining = p->p_numthreads - p->p_boundary_count;
else if (mode == SINGLE_NO_EXIT)
remaining = p->p_numthreads - p->p_suspcount;
else
panic("calc_remaining: wrong mode %d", mode);
return (remaining);
}
/*
* Enforce single-threading.
*
* Returns 1 if the caller must abort (another thread is waiting to
* exit the process or similar). Process is locked!
* Returns 0 when you are successfully the only thread running.
* A process has successfully single threaded in the suspend mode when
* There are no threads in user mode. Threads in the kernel must be
* allowed to continue until they get to the user boundary. They may even
* copy out their return values and data before suspending. They may however be
* accelerated in reaching the user boundary as we will wake up
* any sleeping threads that are interruptable. (PCATCH).
*/
int
thread_single(int mode)
{
struct thread *td;
struct thread *td2;
struct proc *p;
int remaining, wakeup_swapper;
td = curthread;
p = td->td_proc;
mtx_assert(&Giant, MA_NOTOWNED);
PROC_LOCK_ASSERT(p, MA_OWNED);
KASSERT((td != NULL), ("curthread is NULL"));
if ((p->p_flag & P_HADTHREADS) == 0)
return (0);
/* Is someone already single threading? */
if (p->p_singlethread != NULL && p->p_singlethread != td)
return (1);
if (mode == SINGLE_EXIT) {
p->p_flag |= P_SINGLE_EXIT;
p->p_flag &= ~P_SINGLE_BOUNDARY;
} else {
p->p_flag &= ~P_SINGLE_EXIT;
if (mode == SINGLE_BOUNDARY)
p->p_flag |= P_SINGLE_BOUNDARY;
else
p->p_flag &= ~P_SINGLE_BOUNDARY;
}
p->p_flag |= P_STOPPED_SINGLE;
PROC_SLOCK(p);
p->p_singlethread = td;
remaining = calc_remaining(p, mode);
while (remaining != 1) {
if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE)
goto stopme;
wakeup_swapper = 0;
FOREACH_THREAD_IN_PROC(p, td2) {
if (td2 == td)
continue;
thread_lock(td2);
td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK;
if (TD_IS_INHIBITED(td2)) {
switch (mode) {
case SINGLE_EXIT:
if (TD_IS_SUSPENDED(td2))
wakeup_swapper |=
thread_unsuspend_one(td2);
if (TD_ON_SLEEPQ(td2) &&
(td2->td_flags & TDF_SINTR))
wakeup_swapper |=
sleepq_abort(td2, EINTR);
break;
case SINGLE_BOUNDARY:
if (TD_IS_SUSPENDED(td2) &&
!(td2->td_flags & TDF_BOUNDARY))
wakeup_swapper |=
thread_unsuspend_one(td2);
if (TD_ON_SLEEPQ(td2) &&
(td2->td_flags & TDF_SINTR))
wakeup_swapper |=
sleepq_abort(td2, ERESTART);
break;
case SINGLE_NO_EXIT:
if (TD_IS_SUSPENDED(td2) &&
!(td2->td_flags & TDF_BOUNDARY))
wakeup_swapper |=
thread_unsuspend_one(td2);
if (TD_ON_SLEEPQ(td2) &&
(td2->td_flags & TDF_SINTR))
wakeup_swapper |=
sleepq_abort(td2, ERESTART);
break;
default:
break;
}
}
#ifdef SMP
else if (TD_IS_RUNNING(td2) && td != td2) {
forward_signal(td2);
}
#endif
thread_unlock(td2);
}
if (wakeup_swapper)
kick_proc0();
remaining = calc_remaining(p, mode);
/*
* Maybe we suspended some threads.. was it enough?
*/
if (remaining == 1)
break;
stopme:
/*
* Wake us up when everyone else has suspended.
* In the mean time we suspend as well.
*/
thread_suspend_switch(td);
remaining = calc_remaining(p, mode);
}
if (mode == SINGLE_EXIT) {
/*
* We have gotten rid of all the other threads and we
* are about to either exit or exec. In either case,
* we try our utmost to revert to being a non-threaded
* process.
*/
p->p_singlethread = NULL;
p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT);
thread_unthread(td);
}
PROC_SUNLOCK(p);
return (0);
}
/*
* Called in from locations that can safely check to see
* whether we have to suspend or at least throttle for a
* single-thread event (e.g. fork).
*
* Such locations include userret().
* If the "return_instead" argument is non zero, the thread must be able to
* accept 0 (caller may continue), or 1 (caller must abort) as a result.
*
* The 'return_instead' argument tells the function if it may do a
* thread_exit() or suspend, or whether the caller must abort and back
* out instead.
*
* If the thread that set the single_threading request has set the
* P_SINGLE_EXIT bit in the process flags then this call will never return
* if 'return_instead' is false, but will exit.
*
* P_SINGLE_EXIT | return_instead == 0| return_instead != 0
*---------------+--------------------+---------------------
* 0 | returns 0 | returns 0 or 1
* | when ST ends | immediatly
*---------------+--------------------+---------------------
* 1 | thread exits | returns 1
* | | immediatly
* 0 = thread_exit() or suspension ok,
* other = return error instead of stopping the thread.
*
* While a full suspension is under effect, even a single threading
* thread would be suspended if it made this call (but it shouldn't).
* This call should only be made from places where
* thread_exit() would be safe as that may be the outcome unless
* return_instead is set.
*/
int
thread_suspend_check(int return_instead)
{
struct thread *td;
struct proc *p;
int wakeup_swapper;
td = curthread;
p = td->td_proc;
mtx_assert(&Giant, MA_NOTOWNED);
PROC_LOCK_ASSERT(p, MA_OWNED);
while (P_SHOULDSTOP(p) ||
((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) {
if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
KASSERT(p->p_singlethread != NULL,
("singlethread not set"));
/*
* The only suspension in action is a
* single-threading. Single threader need not stop.
* XXX Should be safe to access unlocked
* as it can only be set to be true by us.
*/
if (p->p_singlethread == td)
return (0); /* Exempt from stopping. */
}
if ((p->p_flag & P_SINGLE_EXIT) && return_instead)
return (EINTR);
/* Should we goto user boundary if we didn't come from there? */
if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
(p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
return (ERESTART);
/*
* If the process is waiting for us to exit,
* this thread should just suicide.
* Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
*/
if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
PROC_UNLOCK(p);
tidhash_remove(td);
PROC_LOCK(p);
tdsigcleanup(td);
PROC_SLOCK(p);
thread_stopped(p);
thread_exit();
}
PROC_SLOCK(p);
thread_stopped(p);
if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
if (p->p_numthreads == p->p_suspcount + 1) {
thread_lock(p->p_singlethread);
wakeup_swapper =
thread_unsuspend_one(p->p_singlethread);
thread_unlock(p->p_singlethread);
if (wakeup_swapper)
kick_proc0();
}
}
PROC_UNLOCK(p);
thread_lock(td);
/*
* When a thread suspends, it just
* gets taken off all queues.
*/
thread_suspend_one(td);
if (return_instead == 0) {
p->p_boundary_count++;
td->td_flags |= TDF_BOUNDARY;
}
PROC_SUNLOCK(p);
mi_switch(SW_INVOL | SWT_SUSPEND, NULL);
if (return_instead == 0)
td->td_flags &= ~TDF_BOUNDARY;
thread_unlock(td);
PROC_LOCK(p);
if (return_instead == 0) {
PROC_SLOCK(p);
p->p_boundary_count--;
PROC_SUNLOCK(p);
}
}
return (0);
}
void
thread_suspend_switch(struct thread *td)
{
struct proc *p;
p = td->td_proc;
KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
PROC_LOCK_ASSERT(p, MA_OWNED);
PROC_SLOCK_ASSERT(p, MA_OWNED);
/*
* We implement thread_suspend_one in stages here to avoid
* dropping the proc lock while the thread lock is owned.
*/
thread_stopped(p);
p->p_suspcount++;
PROC_UNLOCK(p);
thread_lock(td);
td->td_flags &= ~TDF_NEEDSUSPCHK;
TD_SET_SUSPENDED(td);
sched_sleep(td, 0);
PROC_SUNLOCK(p);
DROP_GIANT();
mi_switch(SW_VOL | SWT_SUSPEND, NULL);
thread_unlock(td);
PICKUP_GIANT();
PROC_LOCK(p);
PROC_SLOCK(p);
}
void
thread_suspend_one(struct thread *td)
{
struct proc *p = td->td_proc;
PROC_SLOCK_ASSERT(p, MA_OWNED);
THREAD_LOCK_ASSERT(td, MA_OWNED);
KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
p->p_suspcount++;
td->td_flags &= ~TDF_NEEDSUSPCHK;
TD_SET_SUSPENDED(td);
sched_sleep(td, 0);
}
int
thread_unsuspend_one(struct thread *td)
{
struct proc *p = td->td_proc;
PROC_SLOCK_ASSERT(p, MA_OWNED);
THREAD_LOCK_ASSERT(td, MA_OWNED);
KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
TD_CLR_SUSPENDED(td);
p->p_suspcount--;
return (setrunnable(td));
}
/*
* Allow all threads blocked by single threading to continue running.
*/
void
thread_unsuspend(struct proc *p)
{
struct thread *td;
int wakeup_swapper;
PROC_LOCK_ASSERT(p, MA_OWNED);
PROC_SLOCK_ASSERT(p, MA_OWNED);
wakeup_swapper = 0;
if (!P_SHOULDSTOP(p)) {
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
if (TD_IS_SUSPENDED(td)) {
wakeup_swapper |= thread_unsuspend_one(td);
}
thread_unlock(td);
}
} else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) &&
(p->p_numthreads == p->p_suspcount)) {
/*
* Stopping everything also did the job for the single
* threading request. Now we've downgraded to single-threaded,
* let it continue.
*/
thread_lock(p->p_singlethread);
wakeup_swapper = thread_unsuspend_one(p->p_singlethread);
thread_unlock(p->p_singlethread);
}
if (wakeup_swapper)
kick_proc0();
}
/*
* End the single threading mode..
*/
void
thread_single_end(void)
{
struct thread *td;
struct proc *p;
int wakeup_swapper;
td = curthread;
p = td->td_proc;
PROC_LOCK_ASSERT(p, MA_OWNED);
p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY);
PROC_SLOCK(p);
p->p_singlethread = NULL;
wakeup_swapper = 0;
/*
* If there are other threads they may now run,
* unless of course there is a blanket 'stop order'
* on the process. The single threader must be allowed
* to continue however as this is a bad place to stop.
*/
if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) {
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
if (TD_IS_SUSPENDED(td)) {
wakeup_swapper |= thread_unsuspend_one(td);
}
thread_unlock(td);
}
}
PROC_SUNLOCK(p);
if (wakeup_swapper)
kick_proc0();
}
struct thread *
thread_find(struct proc *p, lwpid_t tid)
{
struct thread *td;
PROC_LOCK_ASSERT(p, MA_OWNED);
FOREACH_THREAD_IN_PROC(p, td) {
if (td->td_tid == tid)
break;
}
return (td);
}
/* Locate a thread by number; return with proc lock held. */
struct thread *
tdfind(lwpid_t tid, pid_t pid)
{
#define RUN_THRESH 16
struct thread *td;
int run = 0;
rw_rlock(&tidhash_lock);
LIST_FOREACH(td, TIDHASH(tid), td_hash) {
if (td->td_tid == tid) {
if (pid != -1 && td->td_proc->p_pid != pid) {
td = NULL;
break;
}
PROC_LOCK(td->td_proc);
if (td->td_proc->p_state == PRS_NEW) {
PROC_UNLOCK(td->td_proc);
td = NULL;
break;
}
if (run > RUN_THRESH) {
if (rw_try_upgrade(&tidhash_lock)) {
LIST_REMOVE(td, td_hash);
LIST_INSERT_HEAD(TIDHASH(td->td_tid),
td, td_hash);
rw_wunlock(&tidhash_lock);
return (td);
}
}
break;
}
run++;
}
rw_runlock(&tidhash_lock);
return (td);
}
void
tidhash_add(struct thread *td)
{
rw_wlock(&tidhash_lock);
LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
rw_wunlock(&tidhash_lock);
}
void
tidhash_remove(struct thread *td)
{
rw_wlock(&tidhash_lock);
LIST_REMOVE(td, td_hash);
rw_wunlock(&tidhash_lock);
}