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freebsd-skq/sys/kern/kern_thread.c
davidxu 8e88e8da05 Adjust code for userland preemptive. Userland can set a quantum in 
kse_mailbox to schedule an upcall, this is useful for userland timeout
routine, for example pthread_cond_timedwait().

Also extract upcall scheduling code from kse_reassign and create
a new function called thread_switchout to include these code.

Reviewed by: julain
2003-03-19 05:49:38 +00:00

2065 lines
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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.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/sysproto.h>
#include <sys/filedesc.h>
#include <sys/sched.h>
#include <sys/signalvar.h>
#include <sys/sx.h>
#include <sys/tty.h>
#include <sys/user.h>
#include <sys/jail.h>
#include <sys/kse.h>
#include <sys/ktr.h>
#include <sys/ucontext.h>
#include <vm/vm.h>
#include <vm/vm_object.h>
#include <vm/pmap.h>
#include <vm/uma.h>
#include <vm/vm_map.h>
#include <machine/frame.h>
/*
* KSEGRP related storage.
*/
static uma_zone_t ksegrp_zone;
static uma_zone_t kse_zone;
static uma_zone_t thread_zone;
static uma_zone_t upcall_zone;
/* DEBUG ONLY */
SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0, "thread allocation");
static int thread_debug = 0;
SYSCTL_INT(_kern_threads, OID_AUTO, debug, CTLFLAG_RW,
&thread_debug, 0, "thread debug");
static int max_threads_per_proc = 30;
SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_per_proc, CTLFLAG_RW,
&max_threads_per_proc, 0, "Limit on threads per proc");
static int max_groups_per_proc = 5;
SYSCTL_INT(_kern_threads, OID_AUTO, max_groups_per_proc, CTLFLAG_RW,
&max_groups_per_proc, 0, "Limit on thread groups per proc");
static int max_threads_hits;
SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_hits, CTLFLAG_RD,
&max_threads_hits, 0, "");
static int virtual_cpu;
#define RANGEOF(type, start, end) (offsetof(type, end) - offsetof(type, start))
TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads);
TAILQ_HEAD(, kse) zombie_kses = TAILQ_HEAD_INITIALIZER(zombie_kses);
TAILQ_HEAD(, ksegrp) zombie_ksegrps = TAILQ_HEAD_INITIALIZER(zombie_ksegrps);
TAILQ_HEAD(, kse_upcall) zombie_upcalls =
TAILQ_HEAD_INITIALIZER(zombie_upcalls);
struct mtx kse_zombie_lock;
MTX_SYSINIT(kse_zombie_lock, &kse_zombie_lock, "kse zombie lock", MTX_SPIN);
static void kse_purge(struct proc *p, struct thread *td);
static void kse_purge_group(struct thread *td);
static int thread_update_usr_ticks(struct thread *td, int user);
static void thread_alloc_spare(struct thread *td, struct thread *spare);
static int
sysctl_kse_virtual_cpu(SYSCTL_HANDLER_ARGS)
{
int error, new_val;
int def_val;
#ifdef SMP
def_val = mp_ncpus;
#else
def_val = 1;
#endif
if (virtual_cpu == 0)
new_val = def_val;
else
new_val = virtual_cpu;
error = sysctl_handle_int(oidp, &new_val, 0, req);
if (error != 0 || req->newptr == NULL)
return (error);
if (new_val < 0)
return (EINVAL);
virtual_cpu = new_val;
return (0);
}
/* DEBUG ONLY */
SYSCTL_PROC(_kern_threads, OID_AUTO, virtual_cpu, CTLTYPE_INT|CTLFLAG_RW,
0, sizeof(virtual_cpu), sysctl_kse_virtual_cpu, "I",
"debug virtual cpus");
/*
* Prepare a thread for use.
*/
static void
thread_ctor(void *mem, int size, void *arg)
{
struct thread *td;
td = (struct thread *)mem;
td->td_state = TDS_INACTIVE;
}
/*
* 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
}
/*
* Initialize type-stable parts of a thread (when newly created).
*/
static void
thread_init(void *mem, int size)
{
struct thread *td;
td = (struct thread *)mem;
mtx_lock(&Giant);
pmap_new_thread(td, 0);
mtx_unlock(&Giant);
cpu_thread_setup(td);
td->td_sched = (struct td_sched *)&td[1];
}
/*
* 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;
pmap_dispose_thread(td);
}
/*
* Initialize type-stable parts of a kse (when newly created).
*/
static void
kse_init(void *mem, int size)
{
struct kse *ke;
ke = (struct kse *)mem;
ke->ke_sched = (struct ke_sched *)&ke[1];
}
/*
* Initialize type-stable parts of a ksegrp (when newly created).
*/
static void
ksegrp_init(void *mem, int size)
{
struct ksegrp *kg;
kg = (struct ksegrp *)mem;
kg->kg_sched = (struct kg_sched *)&kg[1];
}
/*
* KSE is linked into kse group.
*/
void
kse_link(struct kse *ke, struct ksegrp *kg)
{
struct proc *p = kg->kg_proc;
TAILQ_INSERT_HEAD(&kg->kg_kseq, ke, ke_kglist);
kg->kg_kses++;
ke->ke_state = KES_UNQUEUED;
ke->ke_proc = p;
ke->ke_ksegrp = kg;
ke->ke_thread = NULL;
ke->ke_oncpu = NOCPU;
ke->ke_flags = 0;
}
void
kse_unlink(struct kse *ke)
{
struct ksegrp *kg;
mtx_assert(&sched_lock, MA_OWNED);
kg = ke->ke_ksegrp;
TAILQ_REMOVE(&kg->kg_kseq, ke, ke_kglist);
if (ke->ke_state == KES_IDLE) {
TAILQ_REMOVE(&kg->kg_iq, ke, ke_kgrlist);
kg->kg_idle_kses--;
}
if (--kg->kg_kses == 0)
ksegrp_unlink(kg);
/*
* Aggregate stats from the KSE
*/
kse_stash(ke);
}
void
ksegrp_link(struct ksegrp *kg, struct proc *p)
{
TAILQ_INIT(&kg->kg_threads);
TAILQ_INIT(&kg->kg_runq); /* links with td_runq */
TAILQ_INIT(&kg->kg_slpq); /* links with td_runq */
TAILQ_INIT(&kg->kg_kseq); /* all kses in ksegrp */
TAILQ_INIT(&kg->kg_iq); /* all idle kses in ksegrp */
TAILQ_INIT(&kg->kg_upcalls); /* all upcall structure in ksegrp */
kg->kg_proc = p;
/*
* the following counters are in the -zero- section
* and may not need clearing
*/
kg->kg_numthreads = 0;
kg->kg_runnable = 0;
kg->kg_kses = 0;
kg->kg_runq_kses = 0; /* XXXKSE change name */
kg->kg_idle_kses = 0;
kg->kg_numupcalls = 0;
/* link it in now that it's consistent */
p->p_numksegrps++;
TAILQ_INSERT_HEAD(&p->p_ksegrps, kg, kg_ksegrp);
}
void
ksegrp_unlink(struct ksegrp *kg)
{
struct proc *p;
mtx_assert(&sched_lock, MA_OWNED);
KASSERT((kg->kg_numthreads == 0), ("ksegrp_unlink: residual threads"));
KASSERT((kg->kg_kses == 0), ("ksegrp_unlink: residual kses"));
KASSERT((kg->kg_numupcalls == 0), ("ksegrp_unlink: residual upcalls"));
p = kg->kg_proc;
TAILQ_REMOVE(&p->p_ksegrps, kg, kg_ksegrp);
p->p_numksegrps--;
/*
* Aggregate stats from the KSE
*/
ksegrp_stash(kg);
}
struct kse_upcall *
upcall_alloc(void)
{
struct kse_upcall *ku;
ku = uma_zalloc(upcall_zone, M_WAITOK);
bzero(ku, sizeof(*ku));
return (ku);
}
void
upcall_free(struct kse_upcall *ku)
{
uma_zfree(upcall_zone, ku);
}
void
upcall_link(struct kse_upcall *ku, struct ksegrp *kg)
{
mtx_assert(&sched_lock, MA_OWNED);
TAILQ_INSERT_TAIL(&kg->kg_upcalls, ku, ku_link);
ku->ku_ksegrp = kg;
kg->kg_numupcalls++;
}
void
upcall_unlink(struct kse_upcall *ku)
{
struct ksegrp *kg = ku->ku_ksegrp;
mtx_assert(&sched_lock, MA_OWNED);
KASSERT(ku->ku_owner == NULL, ("%s: have owner", __func__));
TAILQ_REMOVE(&kg->kg_upcalls, ku, ku_link);
kg->kg_numupcalls--;
upcall_stash(ku);
}
void
upcall_remove(struct thread *td)
{
if (td->td_upcall) {
td->td_upcall->ku_owner = NULL;
upcall_unlink(td->td_upcall);
td->td_upcall = 0;
}
}
/*
* For a newly created process,
* link up all the structures and its initial threads etc.
*/
void
proc_linkup(struct proc *p, struct ksegrp *kg,
struct kse *ke, struct thread *td)
{
TAILQ_INIT(&p->p_ksegrps); /* all ksegrps in proc */
TAILQ_INIT(&p->p_threads); /* all threads in proc */
TAILQ_INIT(&p->p_suspended); /* Threads suspended */
p->p_numksegrps = 0;
p->p_numthreads = 0;
ksegrp_link(kg, p);
kse_link(ke, kg);
thread_link(td, kg);
}
/*
struct kse_thr_interrupt_args {
struct kse_thr_mailbox * tmbx;
};
*/
int
kse_thr_interrupt(struct thread *td, struct kse_thr_interrupt_args *uap)
{
struct proc *p;
struct thread *td2;
p = td->td_proc;
if (!(p->p_flag & P_THREADED) || (uap->tmbx == NULL))
return (EINVAL);
mtx_lock_spin(&sched_lock);
FOREACH_THREAD_IN_PROC(p, td2) {
if (td2->td_mailbox == uap->tmbx) {
td2->td_flags |= TDF_INTERRUPT;
if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR)) {
if (td2->td_flags & TDF_CVWAITQ)
cv_abort(td2);
else
abortsleep(td2);
}
mtx_unlock_spin(&sched_lock);
return (0);
}
}
mtx_unlock_spin(&sched_lock);
return (ESRCH);
}
/*
struct kse_exit_args {
register_t dummy;
};
*/
int
kse_exit(struct thread *td, struct kse_exit_args *uap)
{
struct proc *p;
struct ksegrp *kg;
struct kse *ke;
p = td->td_proc;
/*
* Only UTS can call the syscall and current group
* should be a threaded group.
*/
if ((td->td_mailbox != NULL) || (td->td_ksegrp->kg_numupcalls == 0))
return (EINVAL);
KASSERT((td->td_upcall != NULL), ("%s: not own an upcall", __func__));
kg = td->td_ksegrp;
/* Serialize removing upcall */
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
if ((kg->kg_numupcalls == 1) && (kg->kg_numthreads > 1)) {
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
return (EDEADLK);
}
ke = td->td_kse;
upcall_remove(td);
if (p->p_numthreads == 1) {
kse_purge(p, td);
p->p_flag &= ~P_THREADED;
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
} else {
if (kg->kg_numthreads == 1) { /* Shutdown a group */
kse_purge_group(td);
ke->ke_flags |= KEF_EXIT;
}
thread_stopped(p);
thread_exit();
/* NOTREACHED */
}
return (0);
}
/*
* Either becomes an upcall or waits for an awakening event and
* then becomes an upcall. Only error cases return.
*/
/*
struct kse_release_args {
struct timespec *timeout;
};
*/
int
kse_release(struct thread *td, struct kse_release_args *uap)
{
struct proc *p;
struct ksegrp *kg;
struct timespec ts, ts2, ts3, timeout;
struct timeval tv;
int error;
p = td->td_proc;
kg = td->td_ksegrp;
/*
* Only UTS can call the syscall and current group
* should be a threaded group.
*/
if ((td->td_mailbox != NULL) || (td->td_ksegrp->kg_numupcalls == 0))
return (EINVAL);
KASSERT((td->td_upcall != NULL), ("%s: not own an upcall", __func__));
if (uap->timeout != NULL) {
if ((error = copyin(uap->timeout, &timeout, sizeof(timeout))))
return (error);
getnanouptime(&ts);
timespecadd(&ts, &timeout);
TIMESPEC_TO_TIMEVAL(&tv, &timeout);
}
mtx_lock_spin(&sched_lock);
/* Change OURSELF to become an upcall. */
td->td_flags = TDF_UPCALLING;
if (p->p_sflag & PS_NEEDSIGCHK)
td->td_flags |= TDF_ASTPENDING;
mtx_unlock_spin(&sched_lock);
PROC_LOCK(p);
while ((td->td_upcall->ku_flags & KUF_DOUPCALL) == 0 &&
(kg->kg_completed == NULL)) {
kg->kg_upsleeps++;
error = msleep(&kg->kg_completed, &p->p_mtx, PPAUSE|PCATCH,
"kse_rel", (uap->timeout ? tvtohz(&tv) : 0));
kg->kg_upsleeps--;
PROC_UNLOCK(p);
if (uap->timeout == NULL || error != EWOULDBLOCK)
return (0);
getnanouptime(&ts2);
if (timespeccmp(&ts2, &ts, >=))
return (0);
ts3 = ts;
timespecsub(&ts3, &ts2);
TIMESPEC_TO_TIMEVAL(&tv, &ts3);
PROC_LOCK(p);
}
PROC_UNLOCK(p);
return (0);
}
/* struct kse_wakeup_args {
struct kse_mailbox *mbx;
}; */
int
kse_wakeup(struct thread *td, struct kse_wakeup_args *uap)
{
struct proc *p;
struct ksegrp *kg;
struct kse_upcall *ku;
struct thread *td2;
p = td->td_proc;
td2 = NULL;
ku = NULL;
/* KSE-enabled processes only, please. */
if (!(p->p_flag & P_THREADED))
return (EINVAL);
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
if (uap->mbx) {
FOREACH_KSEGRP_IN_PROC(p, kg) {
FOREACH_UPCALL_IN_GROUP(kg, ku) {
if (ku->ku_mailbox == uap->mbx)
break;
}
if (ku)
break;
}
} else {
kg = td->td_ksegrp;
if (kg->kg_upsleeps) {
wakeup_one(&kg->kg_completed);
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
return (0);
}
ku = TAILQ_FIRST(&kg->kg_upcalls);
}
if (ku) {
if ((td2 = ku->ku_owner) == NULL) {
panic("%s: no owner", __func__);
} else if (TD_ON_SLEEPQ(td2) &&
(td2->td_wchan == &kg->kg_completed)) {
abortsleep(td2);
} else {
ku->ku_flags |= KUF_DOUPCALL;
}
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
return (0);
}
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
return (ESRCH);
}
/*
* No new KSEG: first call: use current KSE, don't schedule an upcall
* All other situations, do allocate max new KSEs and schedule an upcall.
*/
/* struct kse_create_args {
struct kse_mailbox *mbx;
int newgroup;
}; */
int
kse_create(struct thread *td, struct kse_create_args *uap)
{
struct kse *newke;
struct ksegrp *newkg;
struct ksegrp *kg;
struct proc *p;
struct kse_mailbox mbx;
struct kse_upcall *newku;
int err, ncpus;
p = td->td_proc;
if ((err = copyin(uap->mbx, &mbx, sizeof(mbx))))
return (err);
/* Too bad, why hasn't kernel always a cpu counter !? */
#ifdef SMP
ncpus = mp_ncpus;
#else
ncpus = 1;
#endif
if (thread_debug && virtual_cpu != 0)
ncpus = virtual_cpu;
/* Easier to just set it than to test and set */
PROC_LOCK(p);
p->p_flag |= P_THREADED;
PROC_UNLOCK(p);
kg = td->td_ksegrp;
if (uap->newgroup) {
/* Have race condition but it is cheap */
if (p->p_numksegrps >= max_groups_per_proc)
return (EPROCLIM);
/*
* If we want a new KSEGRP it doesn't matter whether
* we have already fired up KSE mode before or not.
* We put the process in KSE mode and create a new KSEGRP.
*/
newkg = ksegrp_alloc();
bzero(&newkg->kg_startzero, RANGEOF(struct ksegrp,
kg_startzero, kg_endzero));
bcopy(&kg->kg_startcopy, &newkg->kg_startcopy,
RANGEOF(struct ksegrp, kg_startcopy, kg_endcopy));
mtx_lock_spin(&sched_lock);
if (p->p_numksegrps >= max_groups_per_proc) {
mtx_unlock_spin(&sched_lock);
ksegrp_free(newkg);
return (EPROCLIM);
}
ksegrp_link(newkg, p);
mtx_unlock_spin(&sched_lock);
} else {
newkg = kg;
}
/*
* Creating upcalls more than number of physical cpu does
* not help performance.
*/
if (newkg->kg_numupcalls >= ncpus)
return (EPROCLIM);
if (newkg->kg_numupcalls == 0) {
/*
* Initialize KSE group, optimized for MP.
* Create KSEs as many as physical cpus, this increases
* concurrent even if userland is not MP safe and can only run
* on single CPU (for early version of libpthread, it is true).
* In ideal world, every physical cpu should execute a thread.
* If there is enough KSEs, threads in kernel can be
* executed parallel on different cpus with full speed,
* Concurrent in kernel shouldn't be restricted by number of
* upcalls userland provides.
* Adding more upcall structures only increases concurrent
* in userland.
* Highest performance configuration is:
* N kses = N upcalls = N phyiscal cpus
*/
while (newkg->kg_kses < ncpus) {
newke = kse_alloc();
bzero(&newke->ke_startzero, RANGEOF(struct kse,
ke_startzero, ke_endzero));
#if 0
mtx_lock_spin(&sched_lock);
bcopy(&ke->ke_startcopy, &newke->ke_startcopy,
RANGEOF(struct kse, ke_startcopy, ke_endcopy));
mtx_unlock_spin(&sched_lock);
#endif
mtx_lock_spin(&sched_lock);
kse_link(newke, newkg);
/* Add engine */
kse_reassign(newke);
mtx_unlock_spin(&sched_lock);
}
}
newku = upcall_alloc();
newku->ku_mailbox = uap->mbx;
newku->ku_func = mbx.km_func;
bcopy(&mbx.km_stack, &newku->ku_stack, sizeof(stack_t));
/* For the first call this may not have been set */
if (td->td_standin == NULL)
thread_alloc_spare(td, NULL);
mtx_lock_spin(&sched_lock);
if (newkg->kg_numupcalls >= ncpus) {
mtx_unlock_spin(&sched_lock);
upcall_free(newku);
return (EPROCLIM);
}
upcall_link(newku, newkg);
if (mbx.km_quantum)
newkg->kg_upquantum = max(1, mbx.km_quantum/tick);
/*
* Each upcall structure has an owner thread, find which
* one owns it.
*/
if (uap->newgroup) {
/*
* Because new ksegrp hasn't thread,
* create an initial upcall thread to own it.
*/
thread_schedule_upcall(td, newku);
} else {
/*
* If current thread hasn't an upcall structure,
* just assign the upcall to it.
*/
if (td->td_upcall == NULL) {
newku->ku_owner = td;
td->td_upcall = newku;
} else {
/*
* Create a new upcall thread to own it.
*/
thread_schedule_upcall(td, newku);
}
}
mtx_unlock_spin(&sched_lock);
return (0);
}
/*
* Fill a ucontext_t with a thread's context information.
*
* This is an analogue to getcontext(3).
*/
void
thread_getcontext(struct thread *td, ucontext_t *uc)
{
/*
* XXX this is declared in a MD include file, i386/include/ucontext.h but
* is used in MI code.
*/
#ifdef __i386__
get_mcontext(td, &uc->uc_mcontext);
#endif
uc->uc_sigmask = td->td_proc->p_sigmask;
}
/*
* Set a thread's context from a ucontext_t.
*
* This is an analogue to setcontext(3).
*/
int
thread_setcontext(struct thread *td, ucontext_t *uc)
{
int ret;
/*
* XXX this is declared in a MD include file, i386/include/ucontext.h but
* is used in MI code.
*/
#ifdef __i386__
ret = set_mcontext(td, &uc->uc_mcontext);
#else
ret = ENOSYS;
#endif
if (ret == 0) {
SIG_CANTMASK(uc->uc_sigmask);
PROC_LOCK(td->td_proc);
td->td_proc->p_sigmask = uc->uc_sigmask;
PROC_UNLOCK(td->td_proc);
}
return (ret);
}
/*
* Initialize global thread allocation resources.
*/
void
threadinit(void)
{
#ifndef __ia64__
thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
thread_ctor, thread_dtor, thread_init, thread_fini,
UMA_ALIGN_CACHE, 0);
#else
/*
* XXX the ia64 kstack allocator is really lame and is at the mercy
* of contigmallloc(). This hackery is to pre-construct a whole
* pile of thread structures with associated kernel stacks early
* in the system startup while contigmalloc() still works. Once we
* have them, keep them. Sigh.
*/
thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
thread_ctor, thread_dtor, thread_init, thread_fini,
UMA_ALIGN_CACHE, UMA_ZONE_NOFREE);
uma_prealloc(thread_zone, 512); /* XXX arbitary */
#endif
ksegrp_zone = uma_zcreate("KSEGRP", sched_sizeof_ksegrp(),
NULL, NULL, ksegrp_init, NULL,
UMA_ALIGN_CACHE, 0);
kse_zone = uma_zcreate("KSE", sched_sizeof_kse(),
NULL, NULL, kse_init, NULL,
UMA_ALIGN_CACHE, 0);
upcall_zone = uma_zcreate("UPCALL", sizeof(struct kse_upcall),
NULL, NULL, NULL, NULL, UMA_ALIGN_CACHE, 0);
}
/*
* Stash an embarasingly extra thread into the zombie thread queue.
*/
void
thread_stash(struct thread *td)
{
mtx_lock_spin(&kse_zombie_lock);
TAILQ_INSERT_HEAD(&zombie_threads, td, td_runq);
mtx_unlock_spin(&kse_zombie_lock);
}
/*
* Stash an embarasingly extra kse into the zombie kse queue.
*/
void
kse_stash(struct kse *ke)
{
mtx_lock_spin(&kse_zombie_lock);
TAILQ_INSERT_HEAD(&zombie_kses, ke, ke_procq);
mtx_unlock_spin(&kse_zombie_lock);
}
/*
* Stash an embarasingly extra upcall into the zombie upcall queue.
*/
void
upcall_stash(struct kse_upcall *ku)
{
mtx_lock_spin(&kse_zombie_lock);
TAILQ_INSERT_HEAD(&zombie_upcalls, ku, ku_link);
mtx_unlock_spin(&kse_zombie_lock);
}
/*
* Stash an embarasingly extra ksegrp into the zombie ksegrp queue.
*/
void
ksegrp_stash(struct ksegrp *kg)
{
mtx_lock_spin(&kse_zombie_lock);
TAILQ_INSERT_HEAD(&zombie_ksegrps, kg, kg_ksegrp);
mtx_unlock_spin(&kse_zombie_lock);
}
/*
* Reap zombie kse resource.
*/
void
thread_reap(void)
{
struct thread *td_first, *td_next;
struct kse *ke_first, *ke_next;
struct ksegrp *kg_first, * kg_next;
struct kse_upcall *ku_first, *ku_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))
|| (!TAILQ_EMPTY(&zombie_kses))
|| (!TAILQ_EMPTY(&zombie_ksegrps))
|| (!TAILQ_EMPTY(&zombie_upcalls))) {
mtx_lock_spin(&kse_zombie_lock);
td_first = TAILQ_FIRST(&zombie_threads);
ke_first = TAILQ_FIRST(&zombie_kses);
kg_first = TAILQ_FIRST(&zombie_ksegrps);
ku_first = TAILQ_FIRST(&zombie_upcalls);
if (td_first)
TAILQ_INIT(&zombie_threads);
if (ke_first)
TAILQ_INIT(&zombie_kses);
if (kg_first)
TAILQ_INIT(&zombie_ksegrps);
if (ku_first)
TAILQ_INIT(&zombie_upcalls);
mtx_unlock_spin(&kse_zombie_lock);
while (td_first) {
td_next = TAILQ_NEXT(td_first, td_runq);
if (td_first->td_ucred)
crfree(td_first->td_ucred);
thread_free(td_first);
td_first = td_next;
}
while (ke_first) {
ke_next = TAILQ_NEXT(ke_first, ke_procq);
kse_free(ke_first);
ke_first = ke_next;
}
while (kg_first) {
kg_next = TAILQ_NEXT(kg_first, kg_ksegrp);
ksegrp_free(kg_first);
kg_first = kg_next;
}
while (ku_first) {
ku_next = TAILQ_NEXT(ku_first, ku_link);
upcall_free(ku_first);
ku_first = ku_next;
}
}
}
/*
* Allocate a ksegrp.
*/
struct ksegrp *
ksegrp_alloc(void)
{
return (uma_zalloc(ksegrp_zone, M_WAITOK));
}
/*
* Allocate a kse.
*/
struct kse *
kse_alloc(void)
{
return (uma_zalloc(kse_zone, M_WAITOK));
}
/*
* Allocate a thread.
*/
struct thread *
thread_alloc(void)
{
thread_reap(); /* check if any zombies to get */
return (uma_zalloc(thread_zone, M_WAITOK));
}
/*
* Deallocate a ksegrp.
*/
void
ksegrp_free(struct ksegrp *td)
{
uma_zfree(ksegrp_zone, td);
}
/*
* Deallocate a kse.
*/
void
kse_free(struct kse *td)
{
uma_zfree(kse_zone, td);
}
/*
* Deallocate a thread.
*/
void
thread_free(struct thread *td)
{
cpu_thread_clean(td);
uma_zfree(thread_zone, td);
}
/*
* Store the thread context in the UTS's mailbox.
* then add the mailbox at the head of a list we are building in user space.
* The list is anchored in the ksegrp structure.
*/
int
thread_export_context(struct thread *td)
{
struct proc *p;
struct ksegrp *kg;
uintptr_t mbx;
void *addr;
int error,temp;
ucontext_t uc;
p = td->td_proc;
kg = td->td_ksegrp;
/* Export the user/machine context. */
addr = (void *)(&td->td_mailbox->tm_context);
error = copyin(addr, &uc, sizeof(ucontext_t));
if (error)
goto bad;
thread_getcontext(td, &uc);
error = copyout(&uc, addr, sizeof(ucontext_t));
if (error)
goto bad;
/* Exports clock ticks in kernel mode */
addr = (caddr_t)(&td->td_mailbox->tm_sticks);
temp = fuword(addr) + td->td_usticks;
if (suword(addr, temp))
goto bad;
/* Get address in latest mbox of list pointer */
addr = (void *)(&td->td_mailbox->tm_next);
/*
* Put the saved address of the previous first
* entry into this one
*/
for (;;) {
mbx = (uintptr_t)kg->kg_completed;
if (suword(addr, mbx)) {
error = EFAULT;
goto bad;
}
PROC_LOCK(p);
if (mbx == (uintptr_t)kg->kg_completed) {
kg->kg_completed = td->td_mailbox;
/*
* The thread context may be taken away by
* other upcall threads when we unlock
* process lock. it's no longer valid to
* use it again in any other places.
*/
td->td_mailbox = NULL;
PROC_UNLOCK(p);
break;
}
PROC_UNLOCK(p);
}
td->td_usticks = 0;
return (0);
bad:
PROC_LOCK(p);
psignal(p, SIGSEGV);
PROC_UNLOCK(p);
/* The mailbox is bad, don't use it */
td->td_mailbox = NULL;
td->td_usticks = 0;
return (error);
}
/*
* Take the list of completed mailboxes for this KSEGRP and put them on this
* upcall's mailbox as it's the next one going up.
*/
static int
thread_link_mboxes(struct ksegrp *kg, struct kse_upcall *ku)
{
struct proc *p = kg->kg_proc;
void *addr;
uintptr_t mbx;
addr = (void *)(&ku->ku_mailbox->km_completed);
for (;;) {
mbx = (uintptr_t)kg->kg_completed;
if (suword(addr, mbx)) {
PROC_LOCK(p);
psignal(p, SIGSEGV);
PROC_UNLOCK(p);
return (EFAULT);
}
PROC_LOCK(p);
if (mbx == (uintptr_t)kg->kg_completed) {
kg->kg_completed = NULL;
PROC_UNLOCK(p);
break;
}
PROC_UNLOCK(p);
}
return (0);
}
/*
* This function should be called at statclock interrupt time
*/
int
thread_statclock(int user)
{
struct thread *td = curthread;
if (td->td_ksegrp->kg_numupcalls == 0)
return (-1);
if (user) {
/* Current always do via ast() */
mtx_lock_spin(&sched_lock);
td->td_flags |= (TDF_USTATCLOCK|TDF_ASTPENDING);
mtx_unlock_spin(&sched_lock);
td->td_uuticks++;
} else {
if (td->td_mailbox != NULL)
td->td_usticks++;
else {
/* XXXKSE
* We will call thread_user_enter() for every
* kernel entry in future, so if the thread mailbox
* is NULL, it must be a UTS kernel, don't account
* clock ticks for it.
*/
}
}
return (0);
}
/*
* Export state clock ticks for userland
*/
static int
thread_update_usr_ticks(struct thread *td, int user)
{
struct proc *p = td->td_proc;
struct kse_thr_mailbox *tmbx;
struct kse_upcall *ku;
struct ksegrp *kg;
caddr_t addr;
uint uticks;
if ((ku = td->td_upcall) == NULL)
return (-1);
tmbx = (void *)fuword((void *)&ku->ku_mailbox->km_curthread);
if ((tmbx == NULL) || (tmbx == (void *)-1))
return (-1);
if (user) {
uticks = td->td_uuticks;
td->td_uuticks = 0;
addr = (caddr_t)&tmbx->tm_uticks;
} else {
uticks = td->td_usticks;
td->td_usticks = 0;
addr = (caddr_t)&tmbx->tm_sticks;
}
if (uticks) {
if (suword(addr, uticks+fuword(addr))) {
PROC_LOCK(p);
psignal(p, SIGSEGV);
PROC_UNLOCK(p);
return (-2);
}
}
kg = td->td_ksegrp;
if (kg->kg_upquantum && ticks >= kg->kg_nextupcall) {
mtx_lock_spin(&sched_lock);
td->td_upcall->ku_flags |= KUF_DOUPCALL;
mtx_unlock_spin(&sched_lock);
}
return (0);
}
/*
* Discard the current thread and exit from its context.
*
* 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)
{
struct thread *td;
struct kse *ke;
struct proc *p;
struct ksegrp *kg;
td = curthread;
kg = td->td_ksegrp;
p = td->td_proc;
ke = td->td_kse;
mtx_assert(&sched_lock, MA_OWNED);
KASSERT(p != NULL, ("thread exiting without a process"));
KASSERT(ke != NULL, ("thread exiting without a kse"));
KASSERT(kg != NULL, ("thread exiting without a kse group"));
PROC_LOCK_ASSERT(p, MA_OWNED);
CTR1(KTR_PROC, "thread_exit: thread %p", td);
KASSERT(!mtx_owned(&Giant), ("dying thread owns giant"));
if (td->td_standin != NULL) {
thread_stash(td->td_standin);
td->td_standin = NULL;
}
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 (p->p_numthreads > 1) {
/*
* Unlink this thread from its proc and the kseg.
* In keeping with the other structs we probably should
* have a thread_unlink() that does some of this but it
* would only be called from here (I think) so it would
* be a waste. (might be useful for proc_fini() as well.)
*/
TAILQ_REMOVE(&p->p_threads, td, td_plist);
p->p_numthreads--;
TAILQ_REMOVE(&kg->kg_threads, td, td_kglist);
kg->kg_numthreads--;
if (p->p_maxthrwaits)
wakeup(&p->p_numthreads);
/*
* The test below is NOT true if we are the
* sole exiting thread. P_STOPPED_SNGL 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_unsuspend_one(p->p_singlethread);
}
}
/*
* Because each upcall structure has an owner thread,
* owner thread exits only when process is in exiting
* state, so upcall to userland is no longer needed,
* deleting upcall structure is safe here.
* So when all threads in a group is exited, all upcalls
* in the group should be automatically freed.
*/
if (td->td_upcall)
upcall_remove(td);
ke->ke_state = KES_UNQUEUED;
ke->ke_thread = NULL;
/*
* Decide what to do with the KSE attached to this thread.
*/
if (ke->ke_flags & KEF_EXIT)
kse_unlink(ke);
else
kse_reassign(ke);
PROC_UNLOCK(p);
td->td_kse = NULL;
td->td_state = TDS_INACTIVE;
td->td_proc = NULL;
td->td_ksegrp = NULL;
td->td_last_kse = NULL;
PCPU_SET(deadthread, td);
} else {
PROC_UNLOCK(p);
}
cpu_throw();
/* NOTREACHED */
}
/*
* Do any thread specific cleanups that may be needed in wait()
* called with Giant held, proc and schedlock not held.
*/
void
thread_wait(struct proc *p)
{
struct thread *td;
KASSERT((p->p_numthreads == 1), ("Muliple threads in wait1()"));
KASSERT((p->p_numksegrps == 1), ("Muliple ksegrps in wait1()"));
FOREACH_THREAD_IN_PROC(p, td) {
if (td->td_standin != NULL) {
thread_free(td->td_standin);
td->td_standin = NULL;
}
cpu_thread_clean(td);
}
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.
*
* Note that we do not link to the proc's ucred here.
* The thread is linked as if running but no KSE assigned.
*/
void
thread_link(struct thread *td, struct ksegrp *kg)
{
struct proc *p;
p = kg->kg_proc;
td->td_state = TDS_INACTIVE;
td->td_proc = p;
td->td_ksegrp = kg;
td->td_last_kse = NULL;
td->td_flags = 0;
td->td_kse = NULL;
LIST_INIT(&td->td_contested);
callout_init(&td->td_slpcallout, 1);
TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist);
TAILQ_INSERT_HEAD(&kg->kg_threads, td, td_kglist);
p->p_numthreads++;
kg->kg_numthreads++;
}
/*
* Purge a ksegrp resource. When a ksegrp is preparing to
* exit, it calls this function.
*/
void
kse_purge_group(struct thread *td)
{
struct ksegrp *kg;
struct kse *ke;
kg = td->td_ksegrp;
KASSERT(kg->kg_numthreads == 1, ("%s: bad thread number", __func__));
while ((ke = TAILQ_FIRST(&kg->kg_iq)) != NULL) {
KASSERT(ke->ke_state == KES_IDLE,
("%s: wrong idle KSE state", __func__));
kse_unlink(ke);
}
KASSERT((kg->kg_kses == 1),
("%s: ksegrp still has %d KSEs", __func__, kg->kg_kses));
KASSERT((kg->kg_numupcalls == 0),
("%s: ksegrp still has %d upcall datas",
__func__, kg->kg_numupcalls));
}
/*
* Purge a process's KSE resource. When a process is preparing to
* exit, it calls kse_purge to release any extra KSE resources in
* the process.
*/
void
kse_purge(struct proc *p, struct thread *td)
{
struct ksegrp *kg;
struct kse *ke;
KASSERT(p->p_numthreads == 1, ("bad thread number"));
mtx_lock_spin(&sched_lock);
while ((kg = TAILQ_FIRST(&p->p_ksegrps)) != NULL) {
TAILQ_REMOVE(&p->p_ksegrps, kg, kg_ksegrp);
p->p_numksegrps--;
/*
* There is no ownership for KSE, after all threads
* in the group exited, it is possible that some KSEs
* were left in idle queue, gc them now.
*/
while ((ke = TAILQ_FIRST(&kg->kg_iq)) != NULL) {
KASSERT(ke->ke_state == KES_IDLE,
("%s: wrong idle KSE state", __func__));
TAILQ_REMOVE(&kg->kg_iq, ke, ke_kgrlist);
kg->kg_idle_kses--;
TAILQ_REMOVE(&kg->kg_kseq, ke, ke_kglist);
kg->kg_kses--;
kse_stash(ke);
}
KASSERT(((kg->kg_kses == 0) && (kg != td->td_ksegrp)) ||
((kg->kg_kses == 1) && (kg == td->td_ksegrp)),
("ksegrp has wrong kg_kses: %d", kg->kg_kses));
KASSERT((kg->kg_numupcalls == 0),
("%s: ksegrp still has %d upcall datas",
__func__, kg->kg_numupcalls));
if (kg != td->td_ksegrp)
ksegrp_stash(kg);
}
TAILQ_INSERT_HEAD(&p->p_ksegrps, td->td_ksegrp, kg_ksegrp);
p->p_numksegrps++;
mtx_unlock_spin(&sched_lock);
}
/*
* This function is intended to be used to initialize a spare thread
* for upcall. Initialize thread's large data area outside sched_lock
* for thread_schedule_upcall().
*/
void
thread_alloc_spare(struct thread *td, struct thread *spare)
{
if (td->td_standin)
return;
if (spare == NULL)
spare = thread_alloc();
td->td_standin = spare;
bzero(&spare->td_startzero,
(unsigned)RANGEOF(struct thread, td_startzero, td_endzero));
spare->td_proc = td->td_proc;
/* Setup PCB and fork address */
cpu_set_upcall(spare, td->td_pcb);
/*
* XXXKSE do we really need this? (default values for the
* frame).
*/
bcopy(td->td_frame, spare->td_frame, sizeof(struct trapframe));
spare->td_ucred = crhold(td->td_ucred);
}
/*
* Create a thread and schedule it for upcall on the KSE given.
* Use our thread's standin so that we don't have to allocate one.
*/
struct thread *
thread_schedule_upcall(struct thread *td, struct kse_upcall *ku)
{
struct thread *td2;
mtx_assert(&sched_lock, MA_OWNED);
/*
* Schedule an upcall thread on specified kse_upcall,
* the kse_upcall must be free.
* td must have a spare thread.
*/
KASSERT(ku->ku_owner == NULL, ("%s: upcall has owner", __func__));
if ((td2 = td->td_standin) != NULL) {
td->td_standin = NULL;
} else {
panic("no reserve thread when scheduling an upcall");
return (NULL);
}
CTR3(KTR_PROC, "thread_schedule_upcall: thread %p (pid %d, %s)",
td2, td->td_proc->p_pid, td->td_proc->p_comm);
bcopy(&td->td_startcopy, &td2->td_startcopy,
(unsigned) RANGEOF(struct thread, td_startcopy, td_endcopy));
thread_link(td2, ku->ku_ksegrp);
/* Let the new thread become owner of the upcall */
ku->ku_owner = td2;
td2->td_upcall = ku;
td2->td_flags = TDF_UPCALLING;
if (td->td_proc->p_sflag & PS_NEEDSIGCHK)
td2->td_flags |= TDF_ASTPENDING;
td2->td_kse = NULL;
td2->td_state = TDS_CAN_RUN;
td2->td_inhibitors = 0;
setrunqueue(td2);
return (td2); /* bogus.. should be a void function */
}
void
thread_signal_add(struct thread *td, int sig)
{
struct kse_upcall *ku;
struct proc *p;
sigset_t ss;
int error;
PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
td = curthread;
ku = td->td_upcall;
p = td->td_proc;
PROC_UNLOCK(p);
error = copyin(&ku->ku_mailbox->km_sigscaught, &ss, sizeof(sigset_t));
if (error)
goto error;
SIGADDSET(ss, sig);
error = copyout(&ss, &ku->ku_mailbox->km_sigscaught, sizeof(sigset_t));
if (error)
goto error;
PROC_LOCK(p);
return;
error:
PROC_LOCK(p);
sigexit(td, SIGILL);
}
/*
* Schedule an upcall to notify a KSE process recieved signals.
*
*/
void
thread_signal_upcall(struct thread *td)
{
mtx_lock_spin(&sched_lock);
td->td_flags |= TDF_UPCALLING;
mtx_unlock_spin(&sched_lock);
return;
}
void
thread_switchout(struct thread *td)
{
struct kse_upcall *ku;
mtx_assert(&sched_lock, MA_OWNED);
/*
* If the outgoing thread is in threaded group and has never
* scheduled an upcall, decide whether this is a short
* or long term event and thus whether or not to schedule
* an upcall.
* If it is a short term event, just suspend it in
* a way that takes its KSE with it.
* Select the events for which we want to schedule upcalls.
* For now it's just sleep.
* XXXKSE eventually almost any inhibition could do.
*/
if (TD_CAN_UNBIND(td) && (td->td_standin) && TD_ON_SLEEPQ(td)) {
/*
* Release ownership of upcall, and schedule an upcall
* thread, this new upcall thread becomes the owner of
* the upcall structure.
*/
ku = td->td_upcall;
ku->ku_owner = NULL;
td->td_upcall = NULL;
td->td_flags &= ~TDF_CAN_UNBIND;
thread_schedule_upcall(td, ku);
}
}
/*
* Setup done on the thread when it enters the kernel.
* XXXKSE Presently only for syscalls but eventually all kernel entries.
*/
void
thread_user_enter(struct proc *p, struct thread *td)
{
struct ksegrp *kg;
struct kse_upcall *ku;
kg = td->td_ksegrp;
/*
* First check that we shouldn't just abort.
* But check if we are the single thread first!
* XXX p_singlethread not locked, but should be safe.
*/
if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
thread_stopped(p);
thread_exit();
/* NOTREACHED */
}
/*
* If we are doing a syscall in a KSE environment,
* note where our mailbox is. There is always the
* possibility that we could do this lazily (in kse_reassign()),
* but for now do it every time.
*/
kg = td->td_ksegrp;
if (kg->kg_numupcalls) {
ku = td->td_upcall;
KASSERT(ku, ("%s: no upcall owned", __func__));
KASSERT((ku->ku_owner == td), ("%s: wrong owner", __func__));
td->td_mailbox =
(void *)fuword((void *)&ku->ku_mailbox->km_curthread);
if ((td->td_mailbox == NULL) ||
(td->td_mailbox == (void *)-1)) {
/* Don't schedule upcall when blocked */
td->td_mailbox = NULL;
mtx_lock_spin(&sched_lock);
td->td_flags &= ~TDF_CAN_UNBIND;
mtx_unlock_spin(&sched_lock);
} else {
if (td->td_standin == NULL)
thread_alloc_spare(td, NULL);
mtx_lock_spin(&sched_lock);
td->td_flags |= TDF_CAN_UNBIND;
mtx_unlock_spin(&sched_lock);
}
}
}
/*
* The extra work we go through if we are a threaded process when we
* return to userland.
*
* If we are a KSE process and returning to user mode, check for
* extra work to do before we return (e.g. for more syscalls
* to complete first). If we were in a critical section, we should
* just return to let it finish. Same if we were in the UTS (in
* which case the mailbox's context's busy indicator will be set).
* The only traps we suport will have set the mailbox.
* We will clear it here.
*/
int
thread_userret(struct thread *td, struct trapframe *frame)
{
int error = 0, upcalls;
struct kse_upcall *ku;
struct ksegrp *kg, *kg2;
struct proc *p;
struct timespec ts;
p = td->td_proc;
kg = td->td_ksegrp;
/* Nothing to do with non-threaded group/process */
if (td->td_ksegrp->kg_numupcalls == 0)
return (0);
/*
* Stat clock interrupt hit in userland, it
* is returning from interrupt, charge thread's
* userland time for UTS.
*/
if (td->td_flags & TDF_USTATCLOCK) {
thread_update_usr_ticks(td, 1);
mtx_lock_spin(&sched_lock);
td->td_flags &= ~TDF_USTATCLOCK;
mtx_unlock_spin(&sched_lock);
if (kg->kg_completed ||
(td->td_upcall->ku_flags & KUF_DOUPCALL))
thread_user_enter(p, td);
}
/*
* Optimisation:
* This thread has not started any upcall.
* If there is no work to report other than ourself,
* then it can return direct to userland.
*/
if (TD_CAN_UNBIND(td)) {
mtx_lock_spin(&sched_lock);
td->td_flags &= ~TDF_CAN_UNBIND;
mtx_unlock_spin(&sched_lock);
ku = td->td_upcall;
if ((p->p_flag & PS_NEEDSIGCHK) == 0 &&
(kg->kg_completed == NULL) &&
(ku->ku_flags & KUF_DOUPCALL) == 0 &&
(kg->kg_upquantum && ticks >= kg->kg_nextupcall)) {
thread_update_usr_ticks(td, 0);
nanotime(&ts);
error = copyout(&ts,
(caddr_t)&ku->ku_mailbox->km_timeofday,
sizeof(ts));
td->td_mailbox = 0;
if (error)
goto out;
return (0);
}
error = thread_export_context(td);
if (error) {
/*
* Failing to do the KSE operation just defaults
* back to synchonous operation, so just return from
* the syscall.
*/
return (0);
}
/*
* There is something to report, and we own an upcall
* strucuture, we can go to userland.
* Turn ourself into an upcall thread.
*/
mtx_lock_spin(&sched_lock);
td->td_flags |= TDF_UPCALLING;
mtx_unlock_spin(&sched_lock);
} else if (td->td_mailbox) {
error = thread_export_context(td);
/* possibly upcall with error? */
PROC_LOCK(p);
/*
* There are upcall threads waiting for
* work to do, wake one of them up.
* XXXKSE Maybe wake all of them up.
*/
if (!error && kg->kg_upsleeps)
wakeup_one(&kg->kg_completed);
mtx_lock_spin(&sched_lock);
thread_stopped(p);
thread_exit();
/* NOTREACHED */
}
KASSERT(TD_CAN_UNBIND(td) == 0, ("can unbind"));
if (p->p_numthreads > max_threads_per_proc) {
max_threads_hits++;
PROC_LOCK(p);
while (p->p_numthreads > max_threads_per_proc) {
if (P_SHOULDSTOP(p))
break;
upcalls = 0;
mtx_lock_spin(&sched_lock);
FOREACH_KSEGRP_IN_PROC(p, kg2) {
if (kg2->kg_numupcalls == 0)
upcalls++;
else
upcalls += kg2->kg_numupcalls;
}
mtx_unlock_spin(&sched_lock);
if (upcalls >= max_threads_per_proc)
break;
p->p_maxthrwaits++;
msleep(&p->p_numthreads, &p->p_mtx, PPAUSE|PCATCH,
"maxthreads", NULL);
p->p_maxthrwaits--;
}
PROC_UNLOCK(p);
}
if (td->td_flags & TDF_UPCALLING) {
kg->kg_nextupcall = ticks+kg->kg_upquantum;
ku = td->td_upcall;
/*
* There is no more work to do and we are going to ride
* this thread up to userland as an upcall.
* Do the last parts of the setup needed for the upcall.
*/
CTR3(KTR_PROC, "userret: upcall thread %p (pid %d, %s)",
td, td->td_proc->p_pid, td->td_proc->p_comm);
/*
* Set user context to the UTS.
* Will use Giant in cpu_thread_clean() because it uses
* kmem_free(kernel_map, ...)
*/
cpu_set_upcall_kse(td, ku);
mtx_lock_spin(&sched_lock);
td->td_flags &= ~TDF_UPCALLING;
if (ku->ku_flags & KUF_DOUPCALL)
ku->ku_flags &= ~KUF_DOUPCALL;
mtx_unlock_spin(&sched_lock);
/*
* Unhook the list of completed threads.
* anything that completes after this gets to
* come in next time.
* Put the list of completed thread mailboxes on
* this KSE's mailbox.
*/
error = thread_link_mboxes(kg, ku);
if (error)
goto out;
/*
* Set state and clear the thread mailbox pointer.
* From now on we are just a bound outgoing process.
* **Problem** userret is often called several times.
* it would be nice if this all happenned only on the first
* time through. (the scan for extra work etc.)
*/
error = suword((caddr_t)&ku->ku_mailbox->km_curthread, 0);
if (error)
goto out;
/* Export current system time */
nanotime(&ts);
error = copyout(&ts, (caddr_t)&ku->ku_mailbox->km_timeofday,
sizeof(ts));
}
out:
if (error) {
/*
* Things are going to be so screwed we should just kill
* the process.
* how do we do that?
*/
PROC_LOCK(td->td_proc);
psignal(td->td_proc, SIGSEGV);
PROC_UNLOCK(td->td_proc);
} else {
/*
* Optimisation:
* Ensure that we have a spare thread available,
* for when we re-enter the kernel.
*/
if (td->td_standin == NULL)
thread_alloc_spare(td, NULL);
}
/*
* Clear thread mailbox first, then clear system tick count.
* The order is important because thread_statclock() use
* mailbox pointer to see if it is an userland thread or
* an UTS kernel thread.
*/
td->td_mailbox = NULL;
td->td_usticks = 0;
return (error); /* go sync */
}
/*
* 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
* accellerated in reaching the user boundary as we will wake up
* any sleeping threads that are interruptable. (PCATCH).
*/
int
thread_single(int force_exit)
{
struct thread *td;
struct thread *td2;
struct proc *p;
td = curthread;
p = td->td_proc;
mtx_assert(&Giant, MA_OWNED);
PROC_LOCK_ASSERT(p, MA_OWNED);
KASSERT((td != NULL), ("curthread is NULL"));
if ((p->p_flag & P_THREADED) == 0)
return (0);
/* Is someone already single threading? */
if (p->p_singlethread)
return (1);
if (force_exit == SINGLE_EXIT) {
p->p_flag |= P_SINGLE_EXIT;
} else
p->p_flag &= ~P_SINGLE_EXIT;
p->p_flag |= P_STOPPED_SINGLE;
p->p_singlethread = td;
/* XXXKSE Which lock protects the below values? */
while ((p->p_numthreads - p->p_suspcount) != 1) {
mtx_lock_spin(&sched_lock);
FOREACH_THREAD_IN_PROC(p, td2) {
if (td2 == td)
continue;
td->td_flags |= TDF_ASTPENDING;
if (TD_IS_INHIBITED(td2)) {
if (force_exit == SINGLE_EXIT) {
if (TD_IS_SUSPENDED(td2)) {
thread_unsuspend_one(td2);
}
if (TD_ON_SLEEPQ(td2) &&
(td2->td_flags & TDF_SINTR)) {
if (td2->td_flags & TDF_CVWAITQ)
cv_abort(td2);
else
abortsleep(td2);
}
} else {
if (TD_IS_SUSPENDED(td2))
continue;
/*
* maybe other inhibitted states too?
* XXXKSE Is it totally safe to
* suspend a non-interruptable thread?
*/
if (td2->td_inhibitors &
(TDI_SLEEPING | TDI_SWAPPED))
thread_suspend_one(td2);
}
}
}
/*
* Maybe we suspended some threads.. was it enough?
*/
if ((p->p_numthreads - p->p_suspcount) == 1) {
mtx_unlock_spin(&sched_lock);
break;
}
/*
* Wake us up when everyone else has suspended.
* In the mean time we suspend as well.
*/
thread_suspend_one(td);
mtx_unlock(&Giant);
PROC_UNLOCK(p);
p->p_stats->p_ru.ru_nvcsw++;
mi_switch();
mtx_unlock_spin(&sched_lock);
mtx_lock(&Giant);
PROC_LOCK(p);
}
if (force_exit == SINGLE_EXIT) {
if (td->td_upcall) {
mtx_lock_spin(&sched_lock);
upcall_remove(td);
mtx_unlock_spin(&sched_lock);
}
kse_purge(p, td);
}
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;
struct ksegrp *kg;
td = curthread;
p = td->td_proc;
kg = td->td_ksegrp;
PROC_LOCK_ASSERT(p, MA_OWNED);
while (P_SHOULDSTOP(p)) {
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 (return_instead)
return (1);
mtx_lock_spin(&sched_lock);
thread_stopped(p);
/*
* 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)) {
while (mtx_owned(&Giant))
mtx_unlock(&Giant);
thread_exit();
}
/*
* When a thread suspends, it just
* moves to the processes's suspend queue
* and stays there.
*/
mtx_assert(&Giant, MA_NOTOWNED);
thread_suspend_one(td);
PROC_UNLOCK(p);
if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
if (p->p_numthreads == p->p_suspcount) {
thread_unsuspend_one(p->p_singlethread);
}
}
p->p_stats->p_ru.ru_nivcsw++;
mi_switch();
mtx_unlock_spin(&sched_lock);
PROC_LOCK(p);
}
return (0);
}
void
thread_suspend_one(struct thread *td)
{
struct proc *p = td->td_proc;
mtx_assert(&sched_lock, MA_OWNED);
KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
p->p_suspcount++;
TD_SET_SUSPENDED(td);
TAILQ_INSERT_TAIL(&p->p_suspended, td, td_runq);
/*
* Hack: If we are suspending but are on the sleep queue
* then we are in msleep or the cv equivalent. We
* want to look like we have two Inhibitors.
* May already be set.. doesn't matter.
*/
if (TD_ON_SLEEPQ(td))
TD_SET_SLEEPING(td);
}
void
thread_unsuspend_one(struct thread *td)
{
struct proc *p = td->td_proc;
mtx_assert(&sched_lock, MA_OWNED);
TAILQ_REMOVE(&p->p_suspended, td, td_runq);
TD_CLR_SUSPENDED(td);
p->p_suspcount--;
setrunnable(td);
}
/*
* Allow all threads blocked by single threading to continue running.
*/
void
thread_unsuspend(struct proc *p)
{
struct thread *td;
mtx_assert(&sched_lock, MA_OWNED);
PROC_LOCK_ASSERT(p, MA_OWNED);
if (!P_SHOULDSTOP(p)) {
while (( td = TAILQ_FIRST(&p->p_suspended))) {
thread_unsuspend_one(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_unsuspend_one(p->p_singlethread);
}
}
void
thread_single_end(void)
{
struct thread *td;
struct proc *p;
td = curthread;
p = td->td_proc;
PROC_LOCK_ASSERT(p, MA_OWNED);
p->p_flag &= ~P_STOPPED_SINGLE;
p->p_singlethread = NULL;
/*
* If there are other threads they mey 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))) {
mtx_lock_spin(&sched_lock);
while (( td = TAILQ_FIRST(&p->p_suspended))) {
thread_unsuspend_one(td);
}
mtx_unlock_spin(&sched_lock);
}
}
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