d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
4d99ef8d55
freebsd-skq/sys/kern/kern_thread.c
Julian Elischer 696058c3c5 Unbreak the KSE code. Keep track of zobie threads using the Per-CPU storage 
during the context switch. Rearrange thread cleanups
to avoid problems with Giant. Clean threads when freed or
when recycled.

Approved by:	re (jhb)
2002-12-10 02:33:45 +00:00

1847 lines
46 KiB
C
Raw Blame History

/*
* 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_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;
if (ke->ke_state == KES_IDLE) {
kg->kg_idle_kses--;
TAILQ_REMOVE(&kg->kg_iq, ke, ke_kgrlist);
}
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_iq); /* idle 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_idle_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 returns as an upcall or exits
*/
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);
mtx_lock_spin(&sched_lock);
if (kg->kg_completed == NULL) {
#if 1 /* temp until signals make new threads */
if (p->p_numthreads == 1) {
/* change OURSELF to become an upcall */
td->td_flags = TDF_UPCALLING;
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
/*
* msleep will not call thread_sched_upcall
* because thread is not UNBOUND.
*/
msleep(p->p_sigacts, NULL,
PPAUSE | PCATCH, "ksepause", 0);
return (0);
}
#endif /* end temp */
thread_exit();
}
/* change OURSELF to become an upcall */
td->td_flags = TDF_UPCALLING;
mtx_unlock_spin(&sched_lock);
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, *ke2;
struct ksegrp *kg;
p = td->td_proc;
/* KSE-enabled processes only, please. */
if (!(p->p_flag & P_KSES))
return EINVAL;
ke = NULL;
mtx_lock_spin(&sched_lock);
if (uap->mbx) {
FOREACH_KSEGRP_IN_PROC(p, kg) {
FOREACH_KSE_IN_GROUP(kg, ke2) {
if (ke2->ke_mailbox != uap->mbx)
continue;
if (ke2->ke_state == KES_IDLE) {
ke = ke2;
goto found;
} else {
mtx_unlock_spin(&sched_lock);
td->td_retval[0] = 0;
td->td_retval[1] = 0;
return (0);
}
}
}
} else {
kg = td->td_ksegrp;
ke = TAILQ_FIRST(&kg->kg_iq);
}
if (ke == NULL) {
mtx_unlock_spin(&sched_lock);
return (ESRCH);
}
found:
thread_schedule_upcall(td, ke);
mtx_unlock_spin(&sched_lock);
td->td_retval[0] = 0;
td->td_retval[1] = 0;
return (0);
}
/*
* 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 == 0) {
thread_getcontext(td, &uc);
error = copyout(&uc, addr, sizeof(ucontext_t));
}
if (error) {
PROC_LOCK(p);
psignal(p, SIGSEGV);
PROC_UNLOCK(p);
return (error);
}
/* 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)) {
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 (EFAULT);
}
/*
* 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;
KASSERT(!(td->td_flags & TDF_UNBOUND), ("thread not bound."));
if (ke->ke_mailbox == NULL)
return 0;
uticks = ke->ke_uuticks;
ke->ke_uuticks = 0;
sticks = ke->ke_usticks;
ke->ke_usticks = 0;
tmbx = (void *)fuword((caddr_t)ke->ke_mailbox
+ offsetof(struct kse_mailbox, km_curthread));
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_thread = NULL;
td->td_kse = NULL;
ke->ke_state = KES_UNQUEUED;
KASSERT((ke->ke_bound != td),
("thread_exit: entered with ke_bound set"));
/*
* 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_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)
{
struct kse *ke;
struct ksegrp *kg;
KASSERT(p->p_numthreads == 1, ("bad thread number"));
mtx_lock_spin(&sched_lock);
while ((kg = TAILQ_FIRST(&p->p_ksegrps)) != NULL) {
while ((ke = TAILQ_FIRST(&kg->kg_iq)) != NULL) {
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);
}
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.
*/
struct thread *
thread_schedule_upcall(struct thread *td, struct kse *ke)
{
struct thread *td2;
struct ksegrp *kg;
int newkse;
mtx_assert(&sched_lock, MA_OWNED);
newkse = (ke != td->td_kse);
/*
* If the kse is already owned by another thread then we can't
* schedule an upcall because the other thread must be BOUND
* which means it is not in a position to take an upcall.
* We must be borrowing the KSE to allow us to complete some in-kernel
* work. When we complete, the Bound thread will have teh 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 (ke->ke_bound && ((ke->ke_bound->td_flags & TDF_UNBOUND) == 0)) {
return (NULL);
}
KASSERT((ke->ke_bound == NULL), ("kse already bound"));
if (ke->ke_state == KES_IDLE) {
kg = ke->ke_ksegrp;
TAILQ_REMOVE(&kg->kg_iq, ke, ke_kgrlist);
kg->kg_idle_kses--;
ke->ke_state = KES_UNQUEUED;
}
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;
/*
* If called from msleep(), 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.
*/
ke->ke_bound = td2;
TD_SET_LOAN(td2);
} else {
ke->ke_bound = NULL;
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 sleep()),
* but for now do it every time.
*/
ke = td->td_kse;
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;
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_UNBOUND;
mtx_unlock_spin(&sched_lock);
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 *td2;
struct proc *p;
struct timespec ts;
error = 0;
unbound = td->td_flags & TDF_UNBOUND;
kg = td->td_ksegrp;
p = td->td_proc;
/*
* Originally 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.
* Unbound threads on the other hand either yield to other work
* or transform into an upcall.
* (having saved their context to user space in both cases)
*/
if (unbound) {
/*
* We are an unbound thread, looking to return to
* user space.
* THere are several possibilities:
* 1) we are using a borrowed KSE. save state and exit.
* kse_reassign() will recycle the kse as needed,
* 2) we are not.. save state, and then convert ourself
* to be an upcall, bound to the KSE.
* if there are others that need the kse,
* give them a chance by doing an mi_switch().
* Because we are bound, control will eventually return
* to us here.
* ***
* Save the thread's context, and link it
* into the KSEGRP's list of completed threads.
*/
error = thread_export_context(td);
td->td_mailbox = NULL;
td->td_usticks = 0;
if (error) {
/*
* If we are not running on a borrowed KSE, then
* failing to do the KSE operation just defaults
* back to synchonous operation, so just return from
* the syscall. If it IS borrowed, 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);
if (td->td_kse->ke_bound == NULL) {
td->td_flags &= ~TDF_UNBOUND;
PROC_UNLOCK(td->td_proc);
mtx_unlock_spin(&sched_lock);
thread_update_uticks();
return (error); /* go sync */
}
thread_exit();
}
/*
* if the KSE is owned and we are borrowing it,
* 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);
if (td->td_kse->ke_bound) {
thread_exit();
}
PROC_UNLOCK(p);
/*
* Turn ourself into a bound upcall.
* We will rely on kse_reassign()
* to make us run at a later time.
* We should look just like a sheduled upcall
* from msleep() or cv_wait().
*/
td->td_flags &= ~TDF_UNBOUND;
td->td_flags |= TDF_UPCALLING;
/* Only get here if we have become an upcall */
} else {
mtx_lock_spin(&sched_lock);
}
/*
* We ARE going back to userland with this KSE.
* Check for threads that need to borrow it.
* Optimisation: don't call mi_switch if no-one wants the KSE.
* Any other thread that comes ready after this missed the boat.
*/
ke = td->td_kse;
if ((td2 = kg->kg_last_assigned))
td2 = TAILQ_NEXT(td2, td_runq);
else
td2 = TAILQ_FIRST(&kg->kg_runq);
if (td2) {
/*
* 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 tha for us.
*/
TD_SET_LOAN(td);
ke->ke_bound = td;
ke->ke_thread = NULL;
p->p_stats->p_ru.ru_nvcsw++;
mi_switch(); /* kse_reassign() will (re)find td2 */
}
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();
/*
* To get here, we know there is no other need for our
* KSE so we can proceed. If not upcalling, go back to
* userspace. If we are, get the upcall set up.
*/
if ((td->td_flags & TDF_UPCALLING) == 0)
return (0);
/*
* We must be an upcall to get this far.
* There is no more work to do and we are going to ride
* this thead/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);
/*
* Put any completed mailboxes on this KSE's list.
*/
error = thread_link_mboxes(kg, ke);
if (error)
goto bad;
/*
* Set state and mailbox.
* 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.)
*/
mtx_lock_spin(&sched_lock);
td->td_flags &= ~TDF_UPCALLING;
mtx_unlock_spin(&sched_lock);
#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) {
nanotime(&ts);
if (copyout(&ts, (caddr_t)&ke->ke_mailbox->km_timeofday,
sizeof(ts))) {
goto bad;
}
}
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);
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;
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);
}
} else {
if (TD_IS_SUSPENDED(td2))
continue;
/* maybe other inhibitted states too? */
if (TD_IS_SLEEPING(td2))
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);
/*
* free extra kses and ksegrps, we needn't worry
* about if current thread is in same ksegrp as
* p_singlethread and last kse in the group
* could be killed, this is protected by kg_numthreads,
* in this case, we deduce that kg_numthreads must > 1.
*/
ke = td->td_kse;
if (ke->ke_bound == NULL &&
((kg->kg_kses != 1) || (kg->kg_numthreads == 1)))
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);
}
}
Reference in New Issue View Git Blame Copy Permalink