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freebsd-dev/sys/kern/kern_kse.c
John Baldwin 961a7b244d Add an implementation of turnstiles and change the sleep mutex code to use 
turnstiles to implement blocking isntead of implementing a thread queue
directly.  These turnstiles are somewhat similar to those used in Solaris 7
as described in Solaris Internals but are also different.

Turnstiles do not come out of a fixed-sized pool.  Rather, each thread is
assigned a turnstile when it is created that it frees when it is destroyed.
When a thread blocks on a lock, it donates its turnstile to that lock to
serve as queue of blocked threads.  The queue associated with a given lock
is found by a lookup in a simple hash table.  The turnstile itself is
protected by a lock associated with its entry in the hash table.  This
means that sched_lock is no longer needed to contest on a mutex.  Instead,
sched_lock is only used when manipulating run queues or thread priorities.
Turnstiles also implement priority propagation inherently.

Currently turnstiles only support mutexes.  Eventually, however, turnstiles
may grow two queue's to support a non-sleepable reader/writer lock
implementation.  For more details, see the comments in sys/turnstile.h and
kern/subr_turnstile.c.

The two primary advantages from the turnstile code include: 1) the size
of struct mutex shrinks by four pointers as it no longer stores the
thread queue linkages directly, and 2) less contention on sched_lock in
SMP systems including the ability for multiple CPUs to contend on different
locks simultaneously (not that this last detail is necessarily that much of
a big win).  Note that 1) means that this commit is a kernel ABI breaker,
so don't mix old modules with a new kernel and vice versa.

Tested on:	i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00

2119 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#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/turnstile.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_extern.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 = 150;
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 = 50;
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;
td->td_oncpu = NOCPU;
td->td_critnest = 1;
}
/*
* 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);
vm_thread_new(td, 0);
mtx_unlock(&Giant);
cpu_thread_setup(td);
td->td_turnstile = turnstile_alloc();
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;
turnstile_free(td->td_turnstile);
vm_thread_dispose(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--;
}
--kg->kg_kses;
/*
* 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 cmd;
long data;
};
*/
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_SA))
return (EINVAL);
switch (uap->cmd) {
case KSE_INTR_SENDSIG:
if (uap->data < 0 || uap->data > _SIG_MAXSIG)
return (EINVAL);
case KSE_INTR_INTERRUPT:
case KSE_INTR_RESTART:
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
FOREACH_THREAD_IN_PROC(p, td2) {
if (td2->td_mailbox == uap->tmbx)
break;
}
if (td2 == NULL) {
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
return (ESRCH);
}
if (uap->cmd == KSE_INTR_SENDSIG) {
if (uap->data > 0) {
td2->td_flags &= ~TDF_INTERRUPT;
mtx_unlock_spin(&sched_lock);
tdsignal(td2, (int)uap->data, SIGTARGET_TD);
} else {
mtx_unlock_spin(&sched_lock);
}
} else {
td2->td_flags |= TDF_INTERRUPT | TDF_ASTPENDING;
if (TD_CAN_UNBIND(td2))
td2->td_upcall->ku_flags |= KUF_DOUPCALL;
if (uap->cmd == KSE_INTR_INTERRUPT)
td2->td_intrval = EINTR;
else
td2->td_intrval = ERESTART;
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);
}
PROC_UNLOCK(p);
break;
case KSE_INTR_SIGEXIT:
if (uap->data < 1 || uap->data > _SIG_MAXSIG)
return (EINVAL);
PROC_LOCK(p);
sigexit(td, (int)uap->data);
break;
default:
return (EINVAL);
}
return (0);
}
/*
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;
struct kse_upcall *ku, *ku2;
int error, count;
p = td->td_proc;
if ((ku = td->td_upcall) == NULL || TD_CAN_UNBIND(td))
return (EINVAL);
kg = td->td_ksegrp;
count = 0;
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
FOREACH_UPCALL_IN_GROUP(kg, ku2) {
if (ku2->ku_flags & KUF_EXITING)
count++;
}
if ((kg->kg_numupcalls - count) == 1 &&
(kg->kg_numthreads > 1)) {
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
return (EDEADLK);
}
ku->ku_flags |= KUF_EXITING;
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
error = suword(&ku->ku_mailbox->km_flags, ku->ku_mflags|KMF_DONE);
PROC_LOCK(p);
if (error)
psignal(p, SIGSEGV);
mtx_lock_spin(&sched_lock);
upcall_remove(td);
ke = td->td_kse;
if (p->p_numthreads == 1) {
kse_purge(p, td);
p->p_flag &= ~P_SA;
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 kse_upcall *ku;
struct timespec timeout;
struct timeval tv;
sigset_t sigset;
int error;
p = td->td_proc;
kg = td->td_ksegrp;
if ((ku = td->td_upcall) == NULL || TD_CAN_UNBIND(td))
return (EINVAL);
if (uap->timeout != NULL) {
if ((error = copyin(uap->timeout, &timeout, sizeof(timeout))))
return (error);
TIMESPEC_TO_TIMEVAL(&tv, &timeout);
}
if (td->td_flags & TDF_SA)
td->td_pflags |= TDP_UPCALLING;
else {
ku->ku_mflags = fuword(&ku->ku_mailbox->km_flags);
if (ku->ku_mflags == -1) {
PROC_LOCK(p);
sigexit(td, SIGSEGV);
}
}
PROC_LOCK(p);
if (ku->ku_mflags & KMF_WAITSIGEVENT) {
/* UTS wants to wait for signal event */
if (!(p->p_flag & P_SIGEVENT) && !(ku->ku_flags & KUF_DOUPCALL))
error = msleep(&p->p_siglist, &p->p_mtx, PPAUSE|PCATCH,
"ksesigwait", (uap->timeout ? tvtohz(&tv) : 0));
p->p_flag &= ~P_SIGEVENT;
sigset = p->p_siglist;
PROC_UNLOCK(p);
error = copyout(&sigset, &ku->ku_mailbox->km_sigscaught,
sizeof(sigset));
} else {
if (! kg->kg_completed && !(ku->ku_flags & KUF_DOUPCALL)) {
kg->kg_upsleeps++;
error = msleep(&kg->kg_completed, &p->p_mtx,
PPAUSE|PCATCH, "kserel",
(uap->timeout ? tvtohz(&tv) : 0));
kg->kg_upsleeps--;
}
PROC_UNLOCK(p);
}
if (ku->ku_flags & KUF_DOUPCALL) {
mtx_lock_spin(&sched_lock);
ku->ku_flags &= ~KUF_DOUPCALL;
mtx_unlock_spin(&sched_lock);
}
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_SA))
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) ||
(td2->td_wchan == &p->p_siglist &&
(ku->ku_mflags & KMF_WAITSIGEVENT)))) {
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, sa = 0, first = 0;
struct thread *newtd;
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 (virtual_cpu != 0)
ncpus = virtual_cpu;
if (!(mbx.km_flags & KMF_BOUND))
sa = TDF_SA;
else
ncpus = 1;
PROC_LOCK(p);
if (!(p->p_flag & P_SA)) {
first = 1;
p->p_flag |= P_SA;
}
PROC_UNLOCK(p);
if (!sa && !uap->newgroup && !first)
return (EINVAL);
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));
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
if (p->p_numksegrps >= max_groups_per_proc) {
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
ksegrp_free(newkg);
return (EPROCLIM);
}
ksegrp_link(newkg, p);
sched_fork_ksegrp(kg, newkg);
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
} else {
if (!first && ((td->td_flags & TDF_SA) ^ sa) != 0)
return (EINVAL);
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
*
* For multiplxed group, create KSEs as many as physical
* cpus. This increases concurrent even if userland
* is not MP safe and can only run on single CPU.
* 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.
*
* For bound thread group, because there is only thread in the
* group, we only create one KSE for the group. Thread in this
* kind of group will never schedule an upcall when blocked,
* this intends to simulate pthread system scope thread.
*/
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);
sched_fork_kse(td->td_kse, newke);
/* 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);
PROC_LOCK(p);
if (newkg->kg_numupcalls >= ncpus) {
PROC_UNLOCK(p);
upcall_free(newku);
return (EPROCLIM);
}
if (first && sa) {
SIGSETOR(p->p_siglist, td->td_siglist);
SIGEMPTYSET(td->td_siglist);
SIGFILLSET(td->td_sigmask);
SIG_CANTMASK(td->td_sigmask);
}
mtx_lock_spin(&sched_lock);
PROC_UNLOCK(p);
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.
*/
newtd = 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;
newtd = td;
} else {
/*
* Create a new upcall thread to own it.
*/
newtd = thread_schedule_upcall(td, newku);
}
}
if (!sa) {
newtd->td_mailbox = mbx.km_curthread;
newtd->td_flags &= ~TDF_SA;
if (newtd != td) {
mtx_unlock_spin(&sched_lock);
cpu_set_upcall_kse(newtd, newku);
mtx_lock_spin(&sched_lock);
}
} else {
newtd->td_flags |= TDF_SA;
}
if (newtd != td)
setrunqueue(newtd);
mtx_unlock_spin(&sched_lock);
return (0);
}
/*
* Initialize global thread allocation resources.
*/
void
threadinit(void)
{
thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
thread_ctor, thread_dtor, thread_init, thread_fini,
UMA_ALIGN_CACHE, 0);
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, int willexit)
{
struct proc *p;
struct ksegrp *kg;
uintptr_t mbx;
void *addr;
int error = 0, temp, sig;
mcontext_t mc;
p = td->td_proc;
kg = td->td_ksegrp;
/* Export the user/machine context. */
get_mcontext(td, &mc, 0);
addr = (void *)(&td->td_mailbox->tm_context.uc_mcontext);
error = copyout(&mc, addr, sizeof(mcontext_t));
if (error)
goto bad;
/* Exports clock ticks in kernel mode */
addr = (caddr_t)(&td->td_mailbox->tm_sticks);
temp = fuword32(addr) + td->td_usticks;
if (suword32(addr, temp)) {
error = EFAULT;
goto bad;
}
/*
* Post sync signal, or process SIGKILL and SIGSTOP.
* For sync signal, it is only possible when the signal is not
* caught by userland or process is being debugged.
*/
PROC_LOCK(p);
if (td->td_flags & TDF_NEEDSIGCHK) {
mtx_lock_spin(&sched_lock);
td->td_flags &= ~TDF_NEEDSIGCHK;
mtx_unlock_spin(&sched_lock);
mtx_lock(&p->p_sigacts->ps_mtx);
while ((sig = cursig(td)) != 0)
postsig(sig);
mtx_unlock(&p->p_sigacts->ps_mtx);
}
if (willexit)
SIGFILLSET(td->td_sigmask);
PROC_UNLOCK(p);
/* 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);
sigexit(td, SIGILL);
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;
struct ksegrp *kg = td->td_ksegrp;
if (kg->kg_numupcalls == 0 || !(td->td_flags & TDF_SA))
return (0);
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;
u_int 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 (suword32(addr, uticks+fuword32(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) {
thread_unlink(td);
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);
sched_exit_thread(FIRST_THREAD_IN_PROC(p), td);
sched_exit_kse(FIRST_KSE_IN_PROC(p), ke);
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);
if (kg->kg_kses == 0) {
sched_exit_ksegrp(FIRST_KSEGRP_IN_PROC(p), kg);
ksegrp_unlink(kg);
}
}
else
kse_reassign(ke);
PROC_UNLOCK(p);
td->td_kse = NULL;
td->td_state = TDS_INACTIVE;
#if 0
td->td_proc = NULL;
#endif
td->td_ksegrp = NULL;
td->td_last_kse = NULL;
PCPU_SET(deadthread, td);
} else {
PROC_UNLOCK(p);
}
/* XXX Shouldn't cpu_throw() here. */
mtx_assert(&sched_lock, MA_OWNED);
cpu_throw(td, choosethread());
panic("I'm a teapot!");
/* 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, CALLOUT_MPSAFE);
TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist);
TAILQ_INSERT_HEAD(&kg->kg_threads, td, td_kglist);
p->p_numthreads++;
kg->kg_numthreads++;
}
void
thread_unlink(struct thread *td)
{
struct proc *p = td->td_proc;
struct ksegrp *kg = td->td_ksegrp;
mtx_assert(&sched_lock, MA_OWNED);
TAILQ_REMOVE(&p->p_threads, td, td_plist);
p->p_numthreads--;
TAILQ_REMOVE(&kg->kg_threads, td, td_kglist);
kg->kg_numthreads--;
/* could clear a few other things here */
}
/*
* Purge a ksegrp resource. When a ksegrp is preparing to
* exit, it calls this function.
*/
static 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.
*/
static void
kse_purge(struct proc *p, struct thread *td)
{
struct ksegrp *kg;
struct kse *ke;
KASSERT(p->p_numthreads == 1, ("bad thread number"));
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++;
}
/*
* 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;
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);
/* inherit blocked thread's context */
cpu_set_upcall(td2, td);
/* Let the new thread become owner of the upcall */
ku->ku_owner = td2;
td2->td_upcall = ku;
td2->td_flags = TDF_SA;
td2->td_pflags = TDP_UPCALLING;
td2->td_kse = NULL;
td2->td_state = TDS_CAN_RUN;
td2->td_inhibitors = 0;
SIGFILLSET(td2->td_sigmask);
SIG_CANTMASK(td2->td_sigmask);
sched_fork_thread(td, td2);
return (td2); /* bogus.. should be a void function */
}
/*
* It is only used when thread generated a trap and process is being
* debugged.
*/
void
thread_signal_add(struct thread *td, int sig)
{
struct proc *p;
siginfo_t siginfo;
struct sigacts *ps;
int error;
p = td->td_proc;
PROC_LOCK_ASSERT(p, MA_OWNED);
ps = p->p_sigacts;
mtx_assert(&ps->ps_mtx, MA_OWNED);
cpu_thread_siginfo(sig, 0, &siginfo);
mtx_unlock(&ps->ps_mtx);
PROC_UNLOCK(p);
error = copyout(&siginfo, &td->td_mailbox->tm_syncsig, sizeof(siginfo));
if (error) {
PROC_LOCK(p);
sigexit(td, SIGILL);
}
PROC_LOCK(p);
SIGADDSET(td->td_sigmask, sig);
mtx_lock(&ps->ps_mtx);
}
void
thread_switchout(struct thread *td)
{
struct kse_upcall *ku;
struct thread *td2;
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;
td2 = thread_schedule_upcall(td, ku);
setrunqueue(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 ksegrp *kg;
struct kse_upcall *ku;
struct kse_thr_mailbox *tmbx;
uint32_t tflags;
kg = td->td_ksegrp;
/*
* First check that we shouldn't just abort.
* But check if we are the single thread first!
*/
if (p->p_flag & P_SINGLE_EXIT) {
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 (td->td_flags & TDF_SA) {
ku = td->td_upcall;
KASSERT(ku, ("%s: no upcall owned", __func__));
KASSERT((ku->ku_owner == td), ("%s: wrong owner", __func__));
KASSERT(!TD_CAN_UNBIND(td), ("%s: can unbind", __func__));
ku->ku_mflags = fuword32((void *)&ku->ku_mailbox->km_flags);
tmbx = (void *)fuword((void *)&ku->ku_mailbox->km_curthread);
if ((tmbx == NULL) || (tmbx == (void *)-1L) ||
(ku->ku_mflags & KMF_NOUPCALL)) {
td->td_mailbox = NULL;
} else {
if (td->td_standin == NULL)
thread_alloc_spare(td, NULL);
tflags = fuword32(&tmbx->tm_flags);
/*
* On some architectures, TP register points to thread
* mailbox but not points to kse mailbox, and userland
* can not atomically clear km_curthread, but can
* use TP register, and set TMF_NOUPCALL in thread
* flag to indicate a critical region.
*/
if (tflags & TMF_NOUPCALL) {
td->td_mailbox = NULL;
} else {
td->td_mailbox = tmbx;
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, uts_crit;
struct kse_upcall *ku;
struct ksegrp *kg, *kg2;
struct proc *p;
struct timespec ts;
p = td->td_proc;
kg = td->td_ksegrp;
ku = td->td_upcall;
/* Nothing to do with bound thread */
if (!(td->td_flags & TDF_SA))
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);
}
uts_crit = (td->td_mailbox == NULL);
/*
* 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;
if ((td->td_flags & TDF_NEEDSIGCHK) == 0 &&
(kg->kg_completed == NULL) &&
(ku->ku_flags & KUF_DOUPCALL) == 0 &&
(kg->kg_upquantum && ticks < kg->kg_nextupcall)) {
mtx_unlock_spin(&sched_lock);
thread_update_usr_ticks(td, 0);
nanotime(&ts);
error = copyout(&ts,
(caddr_t)&ku->ku_mailbox->km_timeofday,
sizeof(ts));
td->td_mailbox = 0;
ku->ku_mflags = 0;
if (error)
goto out;
return (0);
}
mtx_unlock_spin(&sched_lock);
thread_export_context(td, 0);
/*
* There is something to report, and we own an upcall
* strucuture, we can go to userland.
* Turn ourself into an upcall thread.
*/
td->td_pflags |= TDP_UPCALLING;
} else if (td->td_mailbox && (ku == NULL)) {
thread_export_context(td, 1);
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 (kg->kg_upsleeps)
wakeup_one(&kg->kg_completed);
mtx_lock_spin(&sched_lock);
thread_stopped(p);
thread_exit();
/* NOTREACHED */
}
KASSERT(ku != NULL, ("upcall is NULL\n"));
KASSERT(TD_CAN_UNBIND(td) == 0, ("can unbind"));
if (p->p_numthreads > max_threads_per_proc) {
max_threads_hits++;
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
p->p_maxthrwaits++;
while (p->p_numthreads > max_threads_per_proc) {
upcalls = 0;
FOREACH_KSEGRP_IN_PROC(p, kg2) {
if (kg2->kg_numupcalls == 0)
upcalls++;
else
upcalls += kg2->kg_numupcalls;
}
if (upcalls >= max_threads_per_proc)
break;
mtx_unlock_spin(&sched_lock);
if (msleep(&p->p_numthreads, &p->p_mtx, PPAUSE|PCATCH,
"maxthreads", NULL)) {
mtx_lock_spin(&sched_lock);
break;
} else {
mtx_lock_spin(&sched_lock);
}
}
p->p_maxthrwaits--;
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
}
if (td->td_pflags & TDP_UPCALLING) {
uts_crit = 0;
kg->kg_nextupcall = ticks+kg->kg_upquantum;
/*
* 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);
td->td_pflags &= ~TDP_UPCALLING;
if (ku->ku_flags & KUF_DOUPCALL) {
mtx_lock_spin(&sched_lock);
ku->ku_flags &= ~KUF_DOUPCALL;
mtx_unlock_spin(&sched_lock);
}
/*
* Set user context to the UTS
*/
if (!(ku->ku_mflags & KMF_NOUPCALL)) {
cpu_set_upcall_kse(td, ku);
error = suword(&ku->ku_mailbox->km_curthread, 0);
if (error)
goto out;
}
/*
* 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.
*/
if (!(ku->ku_mflags & KMF_NOCOMPLETED) &&
(error = thread_link_mboxes(kg, ku)) != 0)
goto out;
}
if (!uts_crit) {
nanotime(&ts);
error = copyout(&ts, &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);
}
ku->ku_mflags = 0;
/*
* 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_SA) == 0 && p->p_numthreads == 1)
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;
mtx_lock_spin(&sched_lock);
p->p_singlethread = td;
while ((p->p_numthreads - p->p_suspcount) != 1) {
FOREACH_THREAD_IN_PROC(p, td2) {
if (td2 == td)
continue;
td2->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)
break;
/*
* Wake us up when everyone else has suspended.
* In the mean time we suspend as well.
*/
thread_suspend_one(td);
DROP_GIANT();
PROC_UNLOCK(p);
p->p_stats->p_ru.ru_nvcsw++;
mi_switch();
mtx_unlock_spin(&sched_lock);
PICKUP_GIANT();
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
}
if (force_exit == SINGLE_EXIT) {
if (td->td_upcall)
upcall_remove(td);
kse_purge(p, td);
}
mtx_unlock_spin(&sched_lock);
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;
td = curthread;
p = td->td_proc;
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);
if (p->p_flag & P_SA)
thread_exit();
else
thr_exit1();
}
/*
* When a thread suspends, it just
* moves to the processes's suspend queue
* and stays there.
*/
thread_suspend_one(td);
if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
if (p->p_numthreads == p->p_suspcount) {
thread_unsuspend_one(p->p_singlethread);
}
}
DROP_GIANT();
PROC_UNLOCK(p);
p->p_stats->p_ru.ru_nivcsw++;
mi_switch();
mtx_unlock_spin(&sched_lock);
PICKUP_GIANT();
PROC_LOCK(p);
}
return (0);
}
void
thread_suspend_one(struct thread *td)
{
struct proc *p = td->td_proc;
mtx_assert(&sched_lock, MA_OWNED);
PROC_LOCK_ASSERT(p, 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);
PROC_LOCK_ASSERT(p, 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;
mtx_lock_spin(&sched_lock);
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))) {
while (( td = TAILQ_FIRST(&p->p_suspended))) {
thread_unsuspend_one(td);
}
}
mtx_unlock_spin(&sched_lock);
}
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