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freebsd-dev/sys/kern/kern_thread.c
Julian Elischer 93a7aa79d6 Add code to ddb to allow backtracing an arbitrary thread. 
(show thread {address})

Remove the IDLE kse state and replace it with a change in
the way threads sahre KSEs. Every KSE now has a thread, which is
considered its "owner" however a KSE may also be lent to other
threads in the same group to allow completion of in-kernel work.
n this case the owner remains the same and the KSE will revert to the
owner when the other work has been completed.

All creations of upcalls etc. is now done from
kse_reassign() which in turn is called from mi_switch or
thread_exit(). This means that special code can be removed from
msleep() and cv_wait().

kse_release() does not leave a KSE with no thread any more but
converts the existing thread into teh KSE's owner, and sets it up
for doing an upcall. It is just inhibitted from being scheduled until
there is some reason to do an upcall.

Remove all trace of the kse_idle queue since it is no-longer needed.
"Idle" KSEs are now on the loanable queue.
2002-12-28 01:23:07 +00:00

1879 lines
47 KiB
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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;
/* 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");
#define RANGEOF(type, start, end) (offsetof(type, end) - offsetof(type, start))
struct threadqueue 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);
struct mtx zombie_thread_lock;
MTX_SYSINIT(zombie_thread_lock, &zombie_thread_lock,
"zombie_thread_lock", MTX_SPIN);
static void kse_purge(struct proc *p, struct thread *td);
/*
* 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;
td->td_flags |= TDF_UNBOUND;
}
/*
* 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 onto the idle queue.
*/
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_owner = NULL;
ke->ke_thread = NULL;
ke->ke_oncpu = NOCPU;
}
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 (--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_lq); /* loan kses 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_loan_kses = 0;
kg->kg_runq_kses = 0; /* XXXKSE change name */
/* 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);
p = kg->kg_proc;
KASSERT(((kg->kg_numthreads == 0) && (kg->kg_kses == 0)),
("kseg_unlink: residual threads or KSEs"));
TAILQ_REMOVE(&p->p_ksegrps, kg, kg_ksegrp);
p->p_numksegrps--;
/*
* Aggregate stats from the KSE
*/
ksegrp_stash(kg);
}
/*
* for a newly created process,
* link up a the structure 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);
}
int
kse_thr_interrupt(struct thread *td, struct kse_thr_interrupt_args *uap)
{
struct proc *p;
struct thread *td2;
p = td->td_proc;
/* KSE-enabled processes only, please. */
if (!(p->p_flag & P_KSES))
return (EINVAL);
if (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);
td->td_retval[0] = 0;
td->td_retval[1] = 0;
return (0);
}
}
mtx_unlock_spin(&sched_lock);
return (ESRCH);
}
int
kse_exit(struct thread *td, struct kse_exit_args *uap)
{
struct proc *p;
struct ksegrp *kg;
p = td->td_proc;
/* KSE-enabled processes only, please. */
if (!(p->p_flag & P_KSES))
return (EINVAL);
/* must be a bound thread */
if (td->td_flags & TDF_UNBOUND)
return (EINVAL);
kg = td->td_ksegrp;
/* serialize killing kse */
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
if ((kg->kg_kses == 1) && (kg->kg_numthreads > 1)) {
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
return (EDEADLK);
}
if ((p->p_numthreads == 1) && (p->p_numksegrps == 1)) {
/* XXXSKE what if >1 KSE? check.... */
p->p_flag &= ~P_KSES;
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
} else {
td->td_kse->ke_flags |= KEF_EXIT;
thread_exit();
/* NOTREACHED */
}
return (0);
}
/*
* Either becomes an upcall or waits for an awakening event and
* THEN becomes an upcall. Only error cases return.
*/
int
kse_release(struct thread * td, struct kse_release_args * uap)
{
struct proc *p;
struct ksegrp *kg;
p = td->td_proc;
kg = td->td_ksegrp;
/*
* Must be a bound thread. And kse must have a mailbox ready,
* if not, the kse can not generate an upcall.
*/
if (!(p->p_flag & P_KSES) ||
(td->td_flags & TDF_UNBOUND) ||
(td->td_kse->ke_mailbox == NULL))
return (EINVAL);
PROC_LOCK(p);
/* Change OURSELF to become an upcall. */
td->td_flags = TDF_UPCALLING; /* BOUND */
if (kg->kg_completed == NULL) {
/* XXXKSE also look for waiting signals etc. */
/*
* The KSE will however be lendable.
*/
mtx_lock_spin(&sched_lock);
TD_SET_IDLE(td);
PROC_UNLOCK(p);
p->p_stats->p_ru.ru_nvcsw++;
mi_switch();
mtx_unlock_spin(&sched_lock);
} else {
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 kse *ke;
struct ksegrp *kg;
struct thread *td2;
p = td->td_proc;
td2 = NULL;
/* KSE-enabled processes only, please. */
if (!(p->p_flag & P_KSES))
return EINVAL;
PROC_LOCK(p);
if (uap->mbx) {
FOREACH_KSEGRP_IN_PROC(p, kg) {
FOREACH_KSE_IN_GROUP(kg, ke) {
if (ke->ke_mailbox != uap->mbx)
continue;
td2 = ke->ke_owner ;
KASSERT((td2 != NULL),("KSE with no owner"));
if (!TD_IS_IDLE(td2)) {
/* Return silently if no longer idle */
PROC_UNLOCK(p);
td->td_retval[0] = 0;
td->td_retval[1] = 0;
return (0);
}
break;
}
if (td2) {
break;
}
}
} else {
/*
* look for any idle KSE to resurrect.
*/
kg = td->td_ksegrp;
mtx_lock_spin(&sched_lock);
FOREACH_KSE_IN_GROUP(kg, ke) {
td2 = ke->ke_owner;
KASSERT((td2 != NULL),("KSE with no owner2"));
if (TD_IS_IDLE(td2))
break;
}
}
if (td2) {
mtx_lock_spin(&sched_lock);
PROC_UNLOCK(p);
TD_CLR_IDLE(td2);
setrunnable(td2);
mtx_unlock_spin(&sched_lock);
td->td_retval[0] = 0;
td->td_retval[1] = 0;
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 a new KSE and schedule an upcall on it.
*/
/* 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 kse *ke;
struct ksegrp *newkg;
struct ksegrp *kg;
struct proc *p;
struct kse_mailbox mbx;
int err;
p = td->td_proc;
if ((err = copyin(uap->mbx, &mbx, sizeof(mbx))))
return (err);
p->p_flag |= P_KSES; /* easier to just set it than to test and set */
kg = td->td_ksegrp;
if (uap->newgroup) {
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
* and KSE. If our KSE has not got a mailbox yet then
* that doesn't matter, just leave it that way. It will
* ensure that this thread stay BOUND. It's possible
* that the call came form a threaded library and the main
* program knows nothing of threads.
*/
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));
newke = kse_alloc();
} else {
/*
* Otherwise, if we have already set this KSE
* to have a mailbox, we want to make another KSE here,
* but only if there are not already the limit, which
* is 1 per CPU max.
*
* If the current KSE doesn't have a mailbox we just use it
* and give it one.
*
* Because we don't like to access
* the KSE outside of schedlock if we are UNBOUND,
* (because it can change if we are preempted by an interrupt)
* we can deduce it as having a mailbox if we are UNBOUND,
* and only need to actually look at it if we are BOUND,
* which is safe.
*/
if ((td->td_flags & TDF_UNBOUND) || td->td_kse->ke_mailbox) {
if (thread_debug == 0) { /* if debugging, allow more */
#ifdef SMP
if (kg->kg_kses > mp_ncpus)
#endif
return (EPROCLIM);
}
newke = kse_alloc();
} else {
newke = NULL;
}
newkg = NULL;
}
if (newke) {
bzero(&newke->ke_startzero, RANGEOF(struct kse,
ke_startzero, ke_endzero));
#if 0
bcopy(&ke->ke_startcopy, &newke->ke_startcopy,
RANGEOF(struct kse, ke_startcopy, ke_endcopy));
#endif
/* For the first call this may not have been set */
if (td->td_standin == NULL) {
td->td_standin = thread_alloc();
}
mtx_lock_spin(&sched_lock);
if (newkg) {
if (p->p_numksegrps >= max_groups_per_proc) {
mtx_unlock_spin(&sched_lock);
ksegrp_free(newkg);
kse_free(newke);
return (EPROCLIM);
}
ksegrp_link(newkg, p);
}
else
newkg = kg;
kse_link(newke, newkg);
if (p->p_sflag & PS_NEEDSIGCHK)
newke->ke_flags |= KEF_ASTPENDING;
newke->ke_mailbox = uap->mbx;
newke->ke_upcall = mbx.km_func;
bcopy(&mbx.km_stack, &newke->ke_stack, sizeof(stack_t));
thread_schedule_upcall(td, newke);
mtx_unlock_spin(&sched_lock);
} else {
/*
* If we didn't allocate a new KSE then the we are using
* the exisiting (BOUND) kse.
*/
ke = td->td_kse;
ke->ke_mailbox = uap->mbx;
ke->ke_upcall = mbx.km_func;
bcopy(&mbx.km_stack, &ke->ke_stack, sizeof(stack_t));
}
/*
* Fill out the KSE-mode specific fields of the new kse.
*/
td->td_retval[0] = 0;
td->td_retval[1] = 0;
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);
}
/*
* Stash an embarasingly extra thread into the zombie thread queue.
*/
void
thread_stash(struct thread *td)
{
mtx_lock_spin(&zombie_thread_lock);
TAILQ_INSERT_HEAD(&zombie_threads, td, td_runq);
mtx_unlock_spin(&zombie_thread_lock);
}
/*
* Stash an embarasingly extra kse into the zombie kse queue.
*/
void
kse_stash(struct kse *ke)
{
mtx_lock_spin(&zombie_thread_lock);
TAILQ_INSERT_HEAD(&zombie_kses, ke, ke_procq);
mtx_unlock_spin(&zombie_thread_lock);
}
/*
* Stash an embarasingly extra ksegrp into the zombie ksegrp queue.
*/
void
ksegrp_stash(struct ksegrp *kg)
{
mtx_lock_spin(&zombie_thread_lock);
TAILQ_INSERT_HEAD(&zombie_ksegrps, kg, kg_ksegrp);
mtx_unlock_spin(&zombie_thread_lock);
}
/*
* Reap zombie threads.
*/
void
thread_reap(void)
{
struct thread *td_first, *td_next;
struct kse *ke_first, *ke_next;
struct ksegrp *kg_first, * kg_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))) {
mtx_lock_spin(&zombie_thread_lock);
td_first = TAILQ_FIRST(&zombie_threads);
ke_first = TAILQ_FIRST(&zombie_kses);
kg_first = TAILQ_FIRST(&zombie_ksegrps);
if (td_first)
TAILQ_INIT(&zombie_threads);
if (ke_first)
TAILQ_INIT(&zombie_kses);
if (kg_first)
TAILQ_INIT(&zombie_ksegrps);
mtx_unlock_spin(&zombie_thread_lock);
while (td_first) {
td_next = TAILQ_NEXT(td_first, td_runq);
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;
}
}
}
/*
* 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;
ucontext_t uc;
uint temp;
p = td->td_proc;
kg = td->td_ksegrp;
/* Export the user/machine context. */
#if 0
addr = (caddr_t)td->td_mailbox +
offsetof(struct kse_thr_mailbox, tm_context);
#else /* if user pointer arithmetic is valid in the kernel */
addr = (void *)(&td->td_mailbox->tm_context);
#endif
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;
/* get address in latest mbox of list pointer */
#if 0
addr = (caddr_t)td->td_mailbox
+ offsetof(struct kse_thr_mailbox , tm_next);
#else /* if user pointer arithmetic is valid in the kernel */
addr = (void *)(&td->td_mailbox->tm_next);
#endif
/*
* 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;
PROC_UNLOCK(p);
break;
}
PROC_UNLOCK(p);
}
addr = (caddr_t)td->td_mailbox
+ offsetof(struct kse_thr_mailbox, tm_sticks);
temp = fuword(addr) + td->td_usticks;
if (suword(addr, temp))
goto bad;
return (0);
bad:
PROC_LOCK(p);
psignal(p, SIGSEGV);
PROC_UNLOCK(p);
return (error);
}
/*
* Take the list of completed mailboxes for this KSEGRP and put them on this
* KSE's mailbox as it's the next one going up.
*/
static int
thread_link_mboxes(struct ksegrp *kg, struct kse *ke)
{
struct proc *p = kg->kg_proc;
void *addr;
uintptr_t mbx;
#if 0
addr = (caddr_t)ke->ke_mailbox
+ offsetof(struct kse_mailbox, km_completed);
#else /* if user pointer arithmetic is valid in the kernel */
addr = (void *)(&ke->ke_mailbox->km_completed);
#endif
for (;;) {
mbx = (uintptr_t)kg->kg_completed;
if (suword(addr, mbx)) {
PROC_LOCK(p);
psignal(p, SIGSEGV);
PROC_UNLOCK(p);
return (EFAULT);
}
/* XXXKSE could use atomic CMPXCH here */
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_add_ticks_intr(int user, uint ticks)
{
struct thread *td = curthread;
struct kse *ke = td->td_kse;
if (ke->ke_mailbox == NULL)
return -1;
if (user) {
/* Current always do via ast() */
ke->ke_flags |= KEF_ASTPENDING;
ke->ke_uuticks += ticks;
} else {
if (td->td_mailbox != NULL)
td->td_usticks += ticks;
else
ke->ke_usticks += ticks;
}
return 0;
}
static int
thread_update_uticks(void)
{
struct thread *td = curthread;
struct proc *p = td->td_proc;
struct kse *ke = td->td_kse;
struct kse_thr_mailbox *tmbx;
caddr_t addr;
uint uticks, sticks;
if (ke->ke_mailbox == NULL)
return 0;
uticks = ke->ke_uuticks;
ke->ke_uuticks = 0;
sticks = ke->ke_usticks;
ke->ke_usticks = 0;
#if 0
tmbx = (void *)fuword((caddr_t)ke->ke_mailbox
+ offsetof(struct kse_mailbox, km_curthread));
#else /* if user pointer arithmetic is ok in the kernel */
tmbx = (void *)fuword( (void *)&ke->ke_mailbox->km_curthread);
#endif
if ((tmbx == NULL) || (tmbx == (void *)-1))
return 0;
if (uticks) {
addr = (caddr_t)tmbx + offsetof(struct kse_thr_mailbox, tm_uticks);
uticks += fuword(addr);
if (suword(addr, uticks))
goto bad;
}
if (sticks) {
addr = (caddr_t)tmbx + offsetof(struct kse_thr_mailbox, tm_sticks);
sticks += fuword(addr);
if (suword(addr, sticks))
goto bad;
}
return 0;
bad:
PROC_LOCK(p);
psignal(p, SIGSEGV);
PROC_UNLOCK(p);
return -1;
}
/*
* 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--;
/*
* 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);
}
}
/* Reassign this thread's KSE. */
ke->ke_state = KES_UNQUEUED;
/*
* Decide what to do with the KSE attached to this thread.
* XXX Possibly kse_reassign should do both cases as it already
* does some of this.
*/
if (ke->ke_flags & KEF_EXIT) {
KASSERT((ke->ke_owner == td),
("thread_exit: KSE exiting with non-owner thread"));
ke->ke_thread = NULL;
td->td_kse = NULL;
kse_unlink(ke);
} else {
TD_SET_EXITING(td); /* definitly not runnable */
kse_reassign(ke);
}
PROC_UNLOCK(p);
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;
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++;
td->td_kse = NULL;
}
void
kse_purge(struct proc *p, struct thread *td)
{
/* XXXKSE think about this..
may need to wake up threads on loan queue. */
struct ksegrp *kg;
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--;
KASSERT(((kg->kg_kses == 0) && (kg != td->td_ksegrp)) ||
((kg->kg_kses == 1) && (kg == td->td_ksegrp)),
("wrong kg_kses"));
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);
}
/*
* 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 *ke)
{
struct thread *td2;
int newkse;
mtx_assert(&sched_lock, MA_OWNED);
newkse = (ke != td->td_kse);
/*
* If the owner and kse are BOUND then that thread is planning to
* go to userland and upcalls are not expected. So don't make one.
* If it is not bound then make it so with the spare thread
* anf then borrw back the KSE to allow us to complete some in-kernel
* work. When we complete, the Bound thread will have the chance to
* complete. This thread will sleep as planned. Hopefully there will
* eventually be un unbound thread that can be converted to an
* upcall to report the completion of this thread.
*/
if ((td2 = td->td_standin) != NULL) {
td->td_standin = NULL;
} else {
if (newkse)
panic("no reserve thread when called with a new kse");
/*
* If called from (e.g.) sleep and we do not have
* a reserve thread, then we've used it, so do not
* create 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);
bzero(&td2->td_startzero,
(unsigned)RANGEOF(struct thread, td_startzero, td_endzero));
bcopy(&td->td_startcopy, &td2->td_startcopy,
(unsigned) RANGEOF(struct thread, td_startcopy, td_endcopy));
thread_link(td2, ke->ke_ksegrp);
cpu_set_upcall(td2, td->td_pcb);
/*
* XXXKSE do we really need this? (default values for the
* frame).
*/
bcopy(td->td_frame, td2->td_frame, sizeof(struct trapframe));
/*
* Bind the new thread to the KSE,
* and if it's our KSE, lend it back to ourself
* so we can continue running.
*/
td2->td_ucred = crhold(td->td_ucred);
td2->td_flags = TDF_UPCALLING; /* note: BOUND */
td2->td_kse = ke;
td2->td_state = TDS_CAN_RUN;
td2->td_inhibitors = 0;
ke->ke_owner = td2;
/*
* If called from kse_reassign(), we are working on the current
* KSE so fake that we borrowed it. If called from
* kse_create(), don't, as we have a new kse too.
*/
if (!newkse) {
/*
* This thread will be scheduled when the current thread
* blocks, exits or tries to enter userspace, (which ever
* happens first). When that happens the KSe will "revert"
* to this thread in a BOUND manner. Since we are called
* from msleep() this is going to be "very soon" in nearly
* all cases.
*/
TD_SET_LOAN(td2);
} else {
ke->ke_thread = td2;
ke->ke_state = KES_THREAD;
setrunqueue(td2);
}
return (td2); /* bogus.. should be a void function */
}
/*
* Schedule an upcall to notify a KSE process recieved signals.
*
* XXX - Modifying a sigset_t like this is totally bogus.
*/
struct thread *
signal_upcall(struct proc *p, int sig)
{
struct thread *td, *td2;
struct kse *ke;
sigset_t ss;
int error;
PROC_LOCK_ASSERT(p, MA_OWNED);
return (NULL);
td = FIRST_THREAD_IN_PROC(p);
ke = td->td_kse;
PROC_UNLOCK(p);
error = copyin(&ke->ke_mailbox->km_sigscaught, &ss, sizeof(sigset_t));
PROC_LOCK(p);
if (error)
return (NULL);
SIGADDSET(ss, sig);
PROC_UNLOCK(p);
error = copyout(&ss, &ke->ke_mailbox->km_sigscaught, sizeof(sigset_t));
PROC_LOCK(p);
if (error)
return (NULL);
if (td->td_standin == NULL)
td->td_standin = thread_alloc();
mtx_lock_spin(&sched_lock);
td2 = thread_schedule_upcall(td, ke); /* Bogus JRE */
mtx_unlock_spin(&sched_lock);
return (td2);
}
/*
* 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 kse *ke;
/*
* 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_WEXIT) && (p->p_singlethread != td)) {
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
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.
*/
ke = td->td_kse;
td->td_flags &= ~TDF_UNBOUND;
if (ke->ke_mailbox != NULL) {
#if 0
td->td_mailbox = (void *)fuword((caddr_t)ke->ke_mailbox
+ offsetof(struct kse_mailbox, km_curthread));
#else /* if user pointer arithmetic is ok in the kernel */
td->td_mailbox =
(void *)fuword( (void *)&ke->ke_mailbox->km_curthread);
#endif
if ((td->td_mailbox == NULL) ||
(td->td_mailbox == (void *)-1)) {
td->td_mailbox = NULL; /* single thread it.. */
mtx_lock_spin(&sched_lock);
td->td_flags &= ~(TDF_UNBOUND|TDF_CAN_UNBIND);
mtx_unlock_spin(&sched_lock);
} else {
/*
* when thread limit reached, act like that the thread
* has already done an upcall.
*/
if (p->p_numthreads > max_threads_per_proc) {
if (td->td_standin != NULL)
thread_stash(td->td_standin);
td->td_standin = NULL;
} else {
if (td->td_standin == NULL)
td->td_standin = thread_alloc();
}
mtx_lock_spin(&sched_lock);
td->td_flags |= TDF_CAN_UNBIND;
mtx_unlock_spin(&sched_lock);
KASSERT((ke->ke_owner == td),
("thread_user_enter: No starting owner "));
ke->ke_owner = td;
td->td_usticks = 0;
}
}
}
/*
* 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;
int unbound;
struct kse *ke;
struct ksegrp *kg;
struct thread *worktodo;
struct proc *p;
struct timespec ts;
KASSERT((td->td_kse && td->td_kse->ke_thread && td->td_kse->ke_owner),
("thread_userret: bad thread/kse pointers"));
KASSERT((td == curthread),
("thread_userret: bad thread argument"));
kg = td->td_ksegrp;
p = td->td_proc;
error = 0;
unbound = TD_IS_UNBOUND(td);
mtx_lock_spin(&sched_lock);
if ((worktodo = kg->kg_last_assigned))
worktodo = TAILQ_NEXT(worktodo, td_runq);
else
worktodo = TAILQ_FIRST(&kg->kg_runq);
/*
* Permanently bound threads never upcall but they may
* loan out their KSE at this point.
* Upcalls imply bound.. They also may want to do some Philantropy.
* Temporarily bound threads on the other hand either yield
* to other work and transform into an upcall, or proceed back to
* userland.
*/
if (TD_CAN_UNBIND(td)) {
td->td_flags &= ~(TDF_UNBOUND|TDF_CAN_UNBIND);
if (!worktodo && (kg->kg_completed == NULL)) {
/*
* This thread has not started any upcall.
* If there is no work to report other than
* ourself, then it can return direct to userland.
*/
justreturn:
mtx_unlock_spin(&sched_lock);
thread_update_uticks();
td->td_mailbox = NULL;
return (0);
}
mtx_unlock_spin(&sched_lock);
error = thread_export_context(td);
td->td_usticks = 0;
if (error) {
/*
* As we are not running on a borrowed KSE,
* failing to do the KSE operation just defaults
* back to synchonous operation, so just return from
* the syscall.
*/
goto justreturn;
}
mtx_lock_spin(&sched_lock);
/*
* Turn ourself into a bound upcall.
* We will rely on kse_reassign()
* to make us run at a later time.
*/
td->td_flags |= TDF_UPCALLING;
/* there may be more work since we re-locked schedlock */
if ((worktodo = kg->kg_last_assigned))
worktodo = TAILQ_NEXT(worktodo, td_runq);
else
worktodo = TAILQ_FIRST(&kg->kg_runq);
} else if (unbound) {
/*
* We are an unbound thread, looking to
* return to user space. There must be another owner
* of this KSE.
* We are using a borrowed KSE. save state and exit.
* kse_reassign() will recycle the kse as needed,
*/
mtx_unlock_spin(&sched_lock);
error = thread_export_context(td);
td->td_usticks = 0;
if (error) {
/*
* There is nothing we can do.
* We just lose that context. We
* probably should note this somewhere and send
* the process a signal.
*/
PROC_LOCK(td->td_proc);
psignal(td->td_proc, SIGSEGV);
mtx_lock_spin(&sched_lock);
ke = td->td_kse;
/* possibly upcall with error? */
} else {
/*
* Don't make an upcall, just exit so that the owner
* can get its KSE if it wants it.
* Our context is already safely stored for later
* use by the UTS.
*/
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
ke = td->td_kse;
}
/*
* If the owner is idling, we now have something for it
* to report, so make it runnable.
* If the owner is not an upcall, make an attempt to
* ensure that at least one of any IDLED upcalls can
* wake up.
*/
if (ke->ke_owner->td_flags & TDF_UPCALLING) {
TD_CLR_IDLE(ke->ke_owner);
} else {
FOREACH_KSE_IN_GROUP(kg, ke) {
if (TD_IS_IDLE(ke->ke_owner)) {
TD_CLR_IDLE(ke->ke_owner);
}
}
}
thread_exit();
}
/*
* We ARE going back to userland with this KSE.
* We are permanently bound. We may be an upcall.
* If an upcall, check for threads that need to borrow the KSE.
* Any other thread that comes ready after this missed the boat.
*/
ke = td->td_kse;
/*
* If not upcalling, go back to userspace.
* If we are, get the upcall set up.
*/
if (td->td_flags & TDF_UPCALLING) {
if (worktodo) {
/*
* force a switch to more urgent 'in kernel'
* work. Control will return to this thread
* when there is no more work to do.
* kse_reassign() will do that for us.
*/
TD_SET_LOAN(td); /* XXXKSE may not be needed */
p->p_stats->p_ru.ru_nvcsw++;
mi_switch(); /* kse_reassign() will (re)find worktodo */
}
td->td_flags &= ~TDF_UPCALLING;
mtx_unlock_spin(&sched_lock);
/*
* There is no more work to do and we are going to ride
* this thread/KSE 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, ke);
/*
* 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, ke);
if (error)
goto bad;
/*
* 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.)
*/
#if 0
error = suword((caddr_t)ke->ke_mailbox +
offsetof(struct kse_mailbox, km_curthread), 0);
#else /* if user pointer arithmetic is ok in the kernel */
error = suword((caddr_t)&ke->ke_mailbox->km_curthread, 0);
#endif
ke->ke_uuticks = ke->ke_usticks = 0;
if (error)
goto bad;
nanotime(&ts);
if (copyout(&ts,
(caddr_t)&ke->ke_mailbox->km_timeofday, sizeof(ts))) {
goto bad;
}
} else {
mtx_unlock_spin(&sched_lock);
}
/*
* Optimisation:
* Ensure that we have a spare thread available,
* for when we re-enter the kernel.
*/
if (td->td_standin == NULL) {
td->td_standin = thread_alloc();
}
thread_update_uticks();
td->td_mailbox = NULL;
return (0);
bad:
/*
* 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);
td->td_mailbox = NULL;
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_KSES) == 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;
td->td_flags &= ~TDF_UNBOUND;
} 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;
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);
}
if (TD_IS_IDLE(td2)) {
TD_CLR_IDLE(td2);
}
} else {
if (TD_IS_SUSPENDED(td2))
continue;
/* maybe other inhibitted states too? */
if (td2->td_inhibitors &
(TDI_SLEEPING | TDI_SWAPPED |
TDI_LOAN | TDI_IDLE |
TDI_EXITING))
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)
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 kse *ke;
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);
/*
* 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)) {
mtx_lock_spin(&sched_lock);
while (mtx_owned(&Giant))
mtx_unlock(&Giant);
/*
* All threads should be exiting
* Unless they are the active "singlethread".
* destroy un-needed KSEs as we go..
* KSEGRPS may implode too as #kses -> 0.
*/
ke = td->td_kse;
if (ke->ke_owner == td &&
(kg->kg_kses >= kg->kg_numthreads ))
ke->ke_flags |= KEF_EXIT;
thread_exit();
}
/*
* When a thread suspends, it just
* moves to the processes's suspend queue
* and stays there.
*
* XXXKSE if TDF_BOUND is true
* it will not release it's KSE which might
* lead to deadlock if there are not enough KSEs
* to complete all waiting threads.
* Maybe be able to 'lend' it out again.
* (lent kse's can not go back to userland?)
* and can only be lent in STOPPED state.
*/
mtx_lock_spin(&sched_lock);
if ((p->p_flag & P_STOPPED_SIG) &&
(p->p_suspcount+1 == p->p_numthreads)) {
mtx_unlock_spin(&sched_lock);
PROC_LOCK(p->p_pptr);
if ((p->p_pptr->p_procsig->ps_flag &
PS_NOCLDSTOP) == 0) {
psignal(p->p_pptr, SIGCHLD);
}
PROC_UNLOCK(p->p_pptr);
mtx_lock_spin(&sched_lock);
}
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);
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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