/*
* 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/sysctl.h>
#include <sys/filedesc.h>
#include <sys/tty.h>
#include <sys/signalvar.h>
#include <sys/sx.h>
#include <sys/user.h>
#include <sys/jail.h>
#include <sys/kse.h>
#include <sys/ktr.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>
/*
* Thread related storage.
*/
static uma_zone_t thread_zone;
static int allocated_threads;
static int active_threads;
static int cached_threads;
SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0, "thread allocation");
SYSCTL_INT(_kern_threads, OID_AUTO, active, CTLFLAG_RD,
&active_threads, 0, "Number of active threads in system.");
SYSCTL_INT(_kern_threads, OID_AUTO, cached, CTLFLAG_RD,
&cached_threads, 0, "Number of threads in thread cache.");
SYSCTL_INT(_kern_threads, OID_AUTO, allocated, CTLFLAG_RD,
&allocated_threads, 0, "Number of threads in zone.");
static int oiks_debug = 1; /* 0 disable, 1 printf, 2 enter debugger */
SYSCTL_INT(_kern_threads, OID_AUTO, oiks, CTLFLAG_RW,
&oiks_debug, 0, "OIKS thread debug");
#define RANGEOF(type, start, end) (offsetof(type, end) - offsetof(type, start))
struct threadqueue zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads);
struct mtx zombie_thread_lock;
MTX_SYSINIT(zombie_thread_lock, &zombie_thread_lock,
"zombie_thread_lock", MTX_SPIN);
/*
* Pepare a thread for use.
*/
static void
thread_ctor(void *mem, int size, void *arg)
{
struct thread *td;
KASSERT((size == sizeof(struct thread)),
("size mismatch: %d != %d\n", size, (int)sizeof(struct thread)));
td = (struct thread *)mem;
bzero(&td->td_startzero,
(unsigned)RANGEOF(struct thread, td_startzero, td_endzero));
td->td_state = TDS_NEW;
td->td_flags |= TDF_UNBOUND;
#if 0
/*
* Maybe move these here from process creation, but maybe not.
* Moving them here takes them away from their "natural" place
* in the fork process.
*/
/* XXX td_contested does not appear to be initialized for threads! */
LIST_INIT(&td->td_contested);
callout_init(&td->td_slpcallout, 1);
#endif
cached_threads--; /* XXXSMP */
active_threads++; /* XXXSMP */
}
/*
* Reclaim a thread after use.
*/
static void
thread_dtor(void *mem, int size, void *arg)
{
struct thread *td;
KASSERT((size == sizeof(struct thread)),
("size mismatch: %d != %d\n", size, (int)sizeof(struct thread)));
td = (struct thread *)mem;
#ifdef INVARIANTS
/* Verify that this thread is in a safe state to free. */
switch (td->td_state) {
case TDS_SLP:
case TDS_MTX:
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_UNQUEUED:
case TDS_NEW:
case TDS_RUNNING:
case TDS_SURPLUS:
break;
default:
panic("bad thread state");
/* NOTREACHED */
}
#endif
/* Update counters. */
active_threads--; /* XXXSMP */
cached_threads++; /* XXXSMP */
}
/*
* Initialize type-stable parts of a thread (when newly created).
*/
static void
thread_init(void *mem, int size)
{
struct thread *td;
KASSERT((size == sizeof(struct thread)),
("size mismatch: %d != %d\n", size, (int)sizeof(struct thread)));
td = (struct thread *)mem;
pmap_new_thread(td);
cpu_thread_setup(td);
cached_threads++; /* XXXSMP */
allocated_threads++; /* XXXSMP */
}
/*
* Tear down type-stable parts of a thread (just before being discarded).
*/
static void
thread_fini(void *mem, int size)
{
struct thread *td;
KASSERT((size == sizeof(struct thread)),
("size mismatch: %d != %d\n", size, (int)sizeof(struct thread)));
td = (struct thread *)mem;
pmap_dispose_thread(td);
cached_threads--; /* XXXSMP */
allocated_threads--; /* XXXSMP */
}
/*
* Initialize global thread allocation resources.
*/
void
threadinit(void)
{
thread_zone = uma_zcreate("THREAD", sizeof (struct thread),
thread_ctor, thread_dtor, thread_init, thread_fini,
UMA_ALIGN_CACHE, 0);
}
/*
* Stash an embarasingly esxtra 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);
}
/*
* reap any zombie threads.
*/
void
thread_reap(void)
{
struct thread *td_reaped;
/*
* don't even bother to lock if none at this instant
* We really don't care about the next instant..
*/
if (!TAILQ_EMPTY(&zombie_threads)) {
mtx_lock_spin(&zombie_thread_lock);
while (!TAILQ_EMPTY(&zombie_threads)) {
td_reaped = TAILQ_FIRST(&zombie_threads);
TAILQ_REMOVE(&zombie_threads, td_reaped, td_runq);
mtx_unlock_spin(&zombie_thread_lock);
thread_free(td_reaped);
mtx_lock_spin(&zombie_thread_lock);
}
mtx_unlock_spin(&zombie_thread_lock);
}
}
/*
* 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 thread.
*/
void
thread_free(struct thread *td)
{
uma_zfree(thread_zone, td);
}
/*
* Store the thread context in the UTS's mailbox.
*/
int
thread_export_context(struct thread *td)
{
struct kse *ke;
uintptr_t td2_mbx;
void *addr1;
void *addr2;
int error;
#ifdef __ia64__
td2_mbx = 0; /* pacify gcc (!) */
#endif
/* Export the register contents. */
error = cpu_export_context(td);
ke = td->td_kse;
addr1 = (caddr_t)ke->ke_mailbox
+ offsetof(struct kse_mailbox, kmbx_completed_threads);
addr2 = (caddr_t)td->td_mailbox
+ offsetof(struct thread_mailbox , next_completed);
/* Then link it into it's KSE's list of completed threads. */
if (!error) {
error = td2_mbx = fuword(addr1);
if (error == -1)
error = EFAULT;
else
error = 0;
}
if (!error)
error = suword(addr2, td2_mbx);
if (!error)
error = suword(addr1, (u_long)td->td_mailbox);
if (error == -1)
error = EFAULT;
return (error);
}
/*
* 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 KSE's ke_tdspare slot, freeing the
* thread that might be there currently. Because we know that only this
* processor will run our KSE, 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);
PROC_LOCK_ASSERT(p, MA_OWNED);
CTR1(KTR_PROC, "thread_exit: thread %p", td);
KASSERT(!mtx_owned(&Giant), ("dying thread owns giant"));
if (ke->ke_tdspare != NULL) {
thread_stash(ke->ke_tdspare);
ke->ke_tdspare = NULL;
}
cpu_thread_exit(td); /* XXXSMP */
/* Reassign this thread's KSE. */
if (ke != NULL) {
ke->ke_thread = NULL;
td->td_kse = NULL;
ke->ke_state = KES_UNQUEUED;
kse_reassign(ke);
}
/* Unlink this thread from its proc. and the kseg */
if (p != NULL) {
TAILQ_REMOVE(&p->p_threads, td, td_plist);
p->p_numthreads--;
if (kg != NULL) {
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_SNGL) {
if (p->p_numthreads == p->p_suspcount) {
TAILQ_REMOVE(&p->p_suspended,
p->p_singlethread, td_runq);
setrunqueue(p->p_singlethread);
p->p_suspcount--;
}
}
}
td->td_state = TDS_SURPLUS;
td->td_proc = NULL;
td->td_ksegrp = NULL;
td->td_last_kse = NULL;
ke->ke_tdspare = td;
PROC_UNLOCK(p);
cpu_throw();
/* NOTREACHED */
}
/*
* Link a thread to a 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_NEW;
td->td_proc = p;
td->td_ksegrp = kg;
td->td_last_kse = NULL;
TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist);
TAILQ_INSERT_HEAD(&kg->kg_threads, td, td_kglist);
p->p_numthreads++;
kg->kg_numthreads++;
if (oiks_debug && p->p_numthreads > 4) {
printf("OIKS %d\n", p->p_numthreads);
if (oiks_debug > 1)
Debugger("OIKS");
}
td->td_critnest = 0;
td->td_kse = NULL;
}
/*
* Set up the upcall pcb in either a given thread or a new one
* if none given. Use the upcall for the given KSE
* XXXKSE possibly fix cpu_set_upcall() to not need td->td_kse set.
*/
struct thread *
thread_schedule_upcall(struct thread *td, struct kse *ke)
{
struct thread *td2;
mtx_assert(&sched_lock, MA_OWNED);
if (ke->ke_tdspare != NULL) {
td2 = ke->ke_tdspare;
ke->ke_tdspare = NULL;
} else {
mtx_unlock_spin(&sched_lock);
td2 = thread_alloc();
mtx_lock_spin(&sched_lock);
}
CTR3(KTR_PROC, "thread_schedule_upcall: thread %p (pid %d, %s)",
td, td->td_proc->p_pid, td->td_proc->p_comm);
thread_link(td2, ke->ke_ksegrp);
cpu_set_upcall(td2, ke->ke_pcb);
td2->td_ucred = crhold(td->td_ucred);
td2->td_flags = TDF_UNBOUND|TDF_UPCALLING;
td2->td_priority = td->td_priority;
setrunqueue(td2);
return (td2);
}
/*
* 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 we will have no thread mailbox registered). The only
* traps we suport will have set the mailbox. We will clear it here.
*/
int
thread_userret(struct proc *p, struct ksegrp *kg, struct kse *ke,
struct thread *td, struct trapframe *frame)
{
int error = 0;
if (ke->ke_tdspare == NULL) {
ke->ke_tdspare = thread_alloc();
}
if (td->td_flags & TDF_UNBOUND) {
/*
* Are we returning from a thread that had a mailbox?
*
* XXX Maybe this should be in a separate function.
*/
if (((td->td_flags & TDF_UPCALLING) == 0) && td->td_mailbox) {
/*
* [XXXKSE Future enhancement]
* We could also go straight back to the syscall
* if we never had to do an upcall since then.
* If the KSE's copy is == the thread's copy..
* AND there are no other completed threads.
*/
/*
* We will go back as an upcall or go do another thread.
* Either way we need to save the context back to
* the user thread mailbox.
* So the UTS can restart it later.
*/
error = thread_export_context(td);
td->td_mailbox = NULL;
if (error) {
/*
* Failing to do the KSE
* operation just defaults operation
* back to synchonous operation.
*/
goto cont;
}
if (TAILQ_FIRST(&kg->kg_runq)) {
/*
* Uh-oh.. don't return to the user.
* Instead, switch to the thread that
* needs to run. The question is:
* What do we do with the thread we have now?
* We have put the completion block
* on the kse mailbox. If we had more energy,
* we could lazily do so, assuming someone
* else might get to userland earlier
* and deliver it earlier than we could.
* To do that we could save it off the KSEG.
* An upcalling KSE would 'reap' all completed
* threads.
* Being in a hurry, we'll do nothing and
* leave it on the current KSE for now.
*
* As for the other threads to run;
* we COULD rush through all the threads
* in this KSEG at this priority, or we
* could throw the ball back into the court
* and just run the highest prio kse available.
* What is OUR priority?
* the priority of the highest sycall waiting
* to be returned?
* For now, just let another KSE run (easiest).
*/
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
thread_exit(); /* Abandon current thread. */
/* NOTREACHED */
} else { /* if (number of returning syscalls = 1) */
/*
* Swap our frame for the upcall frame.
*
* XXXKSE Assumes we are going to user land
* and not nested in the kernel
*/
td->td_flags |= TDF_UPCALLING;
}
}
/*
* This is NOT just an 'else' clause for the above test...
*/
if (td->td_flags & TDF_UPCALLING) {
CTR3(KTR_PROC, "userret: upcall thread %p (pid %d, %s)",
td, p->p_pid, p->p_comm);
/*
* Make sure that it has the correct frame loaded.
* While we know that we are on the same KSEGRP
* as we were created on, we could very easily
* have come in on another KSE. We therefore need
* to do the copy of the frame after the last
* possible switch() (the one above).
*/
bcopy(ke->ke_frame, frame, sizeof(struct trapframe));
/*
* Decide what we are sending to the user
* upcall sets one argument. The address of the mbox.
*/
cpu_set_args(td, ke);
/*
* There is no more work to do and we are going to ride
* this thead/KSE up to userland. Make sure the user's
* pointer to the thread mailbox is cleared before we
* re-enter the kernel next time for any reason..
* We might as well do it here.
*/
td->td_flags &= ~TDF_UPCALLING; /* Hmmmm. */
error = suword((caddr_t)td->td_kse->ke_mailbox +
offsetof(struct kse_mailbox, kmbx_current_thread),
0);
}
/*
* Stop any chance that we may be separated from
* the KSE we are currently on. This is "biting the bullet",
* we are committing to go to user space as as THIS KSE here.
*/
cont:
td->td_flags &= ~TDF_UNBOUND;
}
return (error);
}
/*
* 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;
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 == SNGLE_EXIT)
p->p_flag |= P_SINGLE_EXIT;
else
p->p_flag &= ~P_SINGLE_EXIT;
p->p_flag |= P_STOPPED_SNGL;
p->p_singlethread = td;
while ((p->p_numthreads - p->p_suspcount) != 1) {
FOREACH_THREAD_IN_PROC(p, td2) {
if (td2 == td)
continue;
switch(td2->td_state) {
case TDS_SUSPENDED:
if (force_exit == SNGLE_EXIT) {
mtx_lock_spin(&sched_lock);
TAILQ_REMOVE(&p->p_suspended,
td, td_runq);
p->p_suspcount--;
setrunqueue(td); /* Should suicide. */
mtx_unlock_spin(&sched_lock);
}
case TDS_SLP:
if (td2->td_flags & TDF_CVWAITQ)
cv_abort(td2);
else
abortsleep(td2);
break;
/* case TDS RUNNABLE: XXXKSE maybe raise priority? */
default: /* needed to avoid an error */
break;
}
}
/*
* Wake us up when everyone else has suspended.
* In the mean time we suspend as well.
*/
mtx_lock_spin(&sched_lock);
TAILQ_INSERT_TAIL(&p->p_suspended, td, td_runq);
td->td_state = TDS_SUSPENDED;
p->p_suspcount++;
mtx_unlock(&Giant);
PROC_UNLOCK(p);
mi_switch();
mtx_unlock_spin(&sched_lock);
mtx_lock(&Giant);
PROC_LOCK(p);
}
return (0);
}
/*
* Called in from locations that can safely check to see
* whether we have to suspend or at least throttle for a
* single-thread event (e.g. fork).
*
* Such locations include userret().
* If the "return_instead" argument is non zero, the thread must be able to
* accept 0 (caller may continue), or 1 (caller must abort) as a result.
*
* The 'return_instead' argument tells the function if it may do a
* thread_exit() or suspend, or whether the caller must abort and back
* out instead.
*
* If the thread that set the single_threading request has set the
* P_SINGLE_EXIT bit in the process flags then this call will never return
* if 'return_instead' is false, but will exit.
*
* P_SINGLE_EXIT | return_instead == 0| return_instead != 0
*---------------+--------------------+---------------------
* 0 | returns 0 | returns 0 or 1
* | when ST ends | immediatly
*---------------+--------------------+---------------------
* 1 | thread exits | returns 1
* | | immediatly
* 0 = thread_exit() or suspension ok,
* other = return error instead of stopping the thread.
*
* While a full suspension is under effect, even a single threading
* thread would be suspended if it made this call (but it shouldn't).
* This call should only be made from places where
* thread_exit() would be safe as that may be the outcome unless
* return_instead is set.
*/
int
thread_suspend_check(int return_instead)
{
struct thread *td = curthread;
struct proc *p = td->td_proc;
td = curthread;
p = td->td_proc;
PROC_LOCK_ASSERT(p, MA_OWNED);
while (P_SHOULDSTOP(p)) {
if (P_SHOULDSTOP(p) == P_STOPPED_SNGL) {
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_SNGL.
*/
if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
mtx_lock_spin(&sched_lock);
while (mtx_owned(&Giant))
mtx_unlock(&Giant);
thread_exit();
}
/*
* When a thread suspends, it just
* moves to the processes's suspend queue
* and stays there.
*
* 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_SGNL) &&
(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_assert(&Giant, MA_NOTOWNED);
mtx_lock_spin(&sched_lock);
p->p_suspcount++;
td->td_state = TDS_SUSPENDED;
TAILQ_INSERT_TAIL(&p->p_suspended, td, td_runq);
PROC_UNLOCK(p);
if (P_SHOULDSTOP(p) == P_STOPPED_SNGL) {
if (p->p_numthreads == p->p_suspcount) {
TAILQ_REMOVE(&p->p_suspended,
p->p_singlethread, td_runq);
p->p_suspcount--;
setrunqueue(p->p_singlethread);
}
}
p->p_stats->p_ru.ru_nivcsw++;
mi_switch();
mtx_unlock_spin(&sched_lock);
PROC_LOCK(p);
}
return (0);
}
/*
* 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))) {
TAILQ_REMOVE(&p->p_suspended, td, td_runq);
p->p_suspcount--;
setrunqueue(td);
}
} else if ((P_SHOULDSTOP(p) == P_STOPPED_SNGL) &&
(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.
*/
TAILQ_REMOVE(&p->p_suspended, p->p_singlethread, td_runq);
p->p_suspcount--;
setrunqueue(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_SNGL;
p->p_singlethread = NULL;
thread_unsuspend(p);
}
