freebsd-dev/sys/kern/kern_thread.c
2007-12-22 04:56:48 +00:00

990 lines
25 KiB
C

/*-
* 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/mutex.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/sched.h>
#include <sys/sleepqueue.h>
#include <sys/selinfo.h>
#include <sys/turnstile.h>
#include <sys/ktr.h>
#include <sys/umtx.h>
#include <security/audit/audit.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/uma.h>
#include <sys/eventhandler.h>
/*
* thread related storage.
*/
static uma_zone_t thread_zone;
SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0, "thread allocation");
int max_threads_per_proc = 1500;
SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_per_proc, CTLFLAG_RW,
&max_threads_per_proc, 0, "Limit on threads per proc");
int max_threads_hits;
SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_hits, CTLFLAG_RD,
&max_threads_hits, 0, "");
#ifdef KSE
int virtual_cpu;
#endif
TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads);
static struct mtx zombie_lock;
MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN);
static void thread_zombie(struct thread *);
#ifdef KSE
static int
sysctl_kse_virtual_cpu(SYSCTL_HANDLER_ARGS)
{
int error, new_val;
int def_val;
def_val = mp_ncpus;
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");
#endif
struct mtx tid_lock;
static struct unrhdr *tid_unrhdr;
/*
* Prepare a thread for use.
*/
static int
thread_ctor(void *mem, int size, void *arg, int flags)
{
struct thread *td;
td = (struct thread *)mem;
td->td_state = TDS_INACTIVE;
td->td_oncpu = NOCPU;
td->td_tid = alloc_unr(tid_unrhdr);
td->td_syscalls = 0;
/*
* Note that td_critnest begins life as 1 because the thread is not
* running and is thereby implicitly waiting to be on the receiving
* end of a context switch.
*/
td->td_critnest = 1;
EVENTHANDLER_INVOKE(thread_ctor, td);
#ifdef AUDIT
audit_thread_alloc(td);
#endif
umtx_thread_alloc(td);
return (0);
}
/*
* 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
#ifdef AUDIT
audit_thread_free(td);
#endif
EVENTHANDLER_INVOKE(thread_dtor, td);
free_unr(tid_unrhdr, td->td_tid);
sched_newthread(td);
}
/*
* Initialize type-stable parts of a thread (when newly created).
*/
static int
thread_init(void *mem, int size, int flags)
{
struct thread *td;
td = (struct thread *)mem;
td->td_sleepqueue = sleepq_alloc();
td->td_turnstile = turnstile_alloc();
EVENTHANDLER_INVOKE(thread_init, td);
td->td_sched = (struct td_sched *)&td[1];
sched_newthread(td);
umtx_thread_init(td);
td->td_kstack = 0;
return (0);
}
/*
* 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;
EVENTHANDLER_INVOKE(thread_fini, td);
turnstile_free(td->td_turnstile);
sleepq_free(td->td_sleepqueue);
umtx_thread_fini(td);
seltdfini(td);
}
/*
* For a newly created process,
* link up all the structures and its initial threads etc.
* called from:
* {arch}/{arch}/machdep.c ia64_init(), init386() etc.
* proc_dtor() (should go away)
* proc_init()
*/
void
proc_linkup0(struct proc *p, struct thread *td)
{
TAILQ_INIT(&p->p_threads); /* all threads in proc */
proc_linkup(p, td);
}
void
proc_linkup(struct proc *p, struct thread *td)
{
#ifdef KSE
TAILQ_INIT(&p->p_upcalls); /* upcall list */
#endif
sigqueue_init(&p->p_sigqueue, p);
p->p_ksi = ksiginfo_alloc(1);
if (p->p_ksi != NULL) {
/* XXX p_ksi may be null if ksiginfo zone is not ready */
p->p_ksi->ksi_flags = KSI_EXT | KSI_INS;
}
LIST_INIT(&p->p_mqnotifier);
p->p_numthreads = 0;
thread_link(td, p);
}
/*
* Initialize global thread allocation resources.
*/
void
threadinit(void)
{
mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
/* leave one number for thread0 */
tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock);
thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
thread_ctor, thread_dtor, thread_init, thread_fini,
16 - 1, 0);
#ifdef KSE
kseinit(); /* set up kse specific stuff e.g. upcall zone*/
#endif
}
/*
* Place an unused thread on the zombie list.
* Use the slpq as that must be unused by now.
*/
void
thread_zombie(struct thread *td)
{
mtx_lock_spin(&zombie_lock);
TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq);
mtx_unlock_spin(&zombie_lock);
}
/*
* Release a thread that has exited after cpu_throw().
*/
void
thread_stash(struct thread *td)
{
atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1);
thread_zombie(td);
}
/*
* Reap zombie kse resource.
*/
void
thread_reap(void)
{
struct thread *td_first, *td_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)) {
mtx_lock_spin(&zombie_lock);
td_first = TAILQ_FIRST(&zombie_threads);
if (td_first)
TAILQ_INIT(&zombie_threads);
mtx_unlock_spin(&zombie_lock);
while (td_first) {
td_next = TAILQ_NEXT(td_first, td_slpq);
if (td_first->td_ucred)
crfree(td_first->td_ucred);
thread_free(td_first);
td_first = td_next;
}
}
#ifdef KSE
upcall_reap();
#endif
}
/*
* Allocate a thread.
*/
struct thread *
thread_alloc(void)
{
struct thread *td;
thread_reap(); /* check if any zombies to get */
td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK);
KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
if (!vm_thread_new(td, 0)) {
uma_zfree(thread_zone, td);
return (NULL);
}
cpu_thread_alloc(td);
return (td);
}
/*
* Deallocate a thread.
*/
void
thread_free(struct thread *td)
{
cpu_thread_free(td);
if (td->td_altkstack != 0)
vm_thread_dispose_altkstack(td);
if (td->td_kstack != 0)
vm_thread_dispose(td);
uma_zfree(thread_zone, td);
}
/*
* Discard the current thread and exit from its context.
* Always called with scheduler locked.
*
* 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(). This may not be needed now as we are under schedlock.
* Maybe we can just do a thread_stash() as thr_exit1 does.
*/
/* XXX
* libthr expects its thread exit to return for the last
* thread, meaning that the program is back to non-threaded
* mode I guess. Because we do this (cpu_throw) unconditionally
* here, they have their own version of it. (thr_exit1())
* that doesn't do it all if this was the last thread.
* It is also called from thread_suspend_check().
* Of course in the end, they end up coming here through exit1
* anyhow.. After fixing 'thr' to play by the rules we should be able
* to merge these two functions together.
*
* called from:
* exit1()
* kse_exit()
* thr_exit()
* ifdef KSE
* thread_user_enter()
* thread_userret()
* endif
* thread_suspend_check()
*/
void
thread_exit(void)
{
uint64_t new_switchtime;
struct thread *td;
struct thread *td2;
struct proc *p;
td = curthread;
p = td->td_proc;
PROC_SLOCK_ASSERT(p, MA_OWNED);
mtx_assert(&Giant, MA_NOTOWNED);
PROC_LOCK_ASSERT(p, MA_OWNED);
KASSERT(p != NULL, ("thread exiting without a process"));
CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
(long)p->p_pid, td->td_name);
KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
#ifdef AUDIT
AUDIT_SYSCALL_EXIT(0, td);
#endif
#ifdef KSE
if (td->td_standin != NULL) {
/*
* Note that we don't need to free the cred here as it
* is done in thread_reap().
*/
thread_zombie(td->td_standin);
td->td_standin = NULL;
}
#endif
umtx_thread_exit(td);
/*
* drop FPU & debug register state storage, or any other
* architecture specific resources that
* would not be on a new untouched process.
*/
cpu_thread_exit(td); /* XXXSMP */
/* Do the same timestamp bookkeeping that mi_switch() would do. */
new_switchtime = cpu_ticks();
p->p_rux.rux_runtime += (new_switchtime - PCPU_GET(switchtime));
PCPU_SET(switchtime, new_switchtime);
PCPU_SET(switchticks, ticks);
PCPU_INC(cnt.v_swtch);
/* Save our resource usage in our process. */
td->td_ru.ru_nvcsw++;
rucollect(&p->p_ru, &td->td_ru);
/*
* The last thread is left attached to the process
* So that the whole bundle gets recycled. Skip
* all this stuff if we never had threads.
* EXIT clears all sign of other threads when
* it goes to single threading, so the last thread always
* takes the short path.
*/
if (p->p_flag & P_HADTHREADS) {
if (p->p_numthreads > 1) {
thread_lock(td);
#ifdef KSE
kse_unlink(td);
#else
thread_unlink(td);
#endif
thread_unlock(td);
td2 = FIRST_THREAD_IN_PROC(p);
sched_exit_thread(td2, td);
/*
* 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_lock(p->p_singlethread);
thread_unsuspend_one(p->p_singlethread);
thread_unlock(p->p_singlethread);
}
}
atomic_add_int(&td->td_proc->p_exitthreads, 1);
PCPU_SET(deadthread, td);
} else {
/*
* The last thread is exiting.. but not through exit()
* what should we do?
* Theoretically this can't happen
* exit1() - clears threading flags before coming here
* kse_exit() - treats last thread specially
* thr_exit() - treats last thread specially
* ifdef KSE
* thread_user_enter() - only if more exist
* thread_userret() - only if more exist
* endif
* thread_suspend_check() - only if more exist
*/
panic ("thread_exit: Last thread exiting on its own");
}
}
PROC_UNLOCK(p);
thread_lock(td);
/* Save our tick information with both the thread and proc locked */
ruxagg(&p->p_rux, td);
PROC_SUNLOCK(p);
td->td_state = TDS_INACTIVE;
CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
sched_throw(td);
panic("I'm a teapot!");
/* NOTREACHED */
}
/*
* Do any thread specific cleanups that may be needed in wait()
* called with Giant, proc and schedlock not held.
*/
void
thread_wait(struct proc *p)
{
struct thread *td;
mtx_assert(&Giant, MA_NOTOWNED);
KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()"));
td = FIRST_THREAD_IN_PROC(p);
#ifdef KSE
if (td->td_standin != NULL) {
if (td->td_standin->td_ucred != NULL) {
crfree(td->td_standin->td_ucred);
td->td_standin->td_ucred = NULL;
}
thread_free(td->td_standin);
td->td_standin = NULL;
}
#endif
/* Lock the last thread so we spin until it exits cpu_throw(). */
thread_lock(td);
thread_unlock(td);
/* Wait for any remaining threads to exit cpu_throw(). */
while (p->p_exitthreads)
sched_relinquish(curthread);
cpu_thread_clean(td);
crfree(td->td_ucred);
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.
* Called from:
* proc_linkup()
* thread_schedule_upcall()
* thr_create()
*/
void
thread_link(struct thread *td, struct proc *p)
{
/*
* XXX This can't be enabled because it's called for proc0 before
* it's spinlock has been created.
* PROC_SLOCK_ASSERT(p, MA_OWNED);
*/
td->td_state = TDS_INACTIVE;
td->td_proc = p;
td->td_flags = TDF_INMEM;
LIST_INIT(&td->td_contested);
LIST_INIT(&td->td_lprof[0]);
LIST_INIT(&td->td_lprof[1]);
sigqueue_init(&td->td_sigqueue, p);
callout_init(&td->td_slpcallout, CALLOUT_MPSAFE);
TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist);
p->p_numthreads++;
}
/*
* Convert a process with one thread to an unthreaded process.
* Called from:
* thread_single(exit) (called from execve and exit)
* kse_exit() XXX may need cleaning up wrt KSE stuff
*/
void
thread_unthread(struct thread *td)
{
struct proc *p = td->td_proc;
KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads"));
#ifdef KSE
thread_lock(td);
upcall_remove(td);
thread_unlock(td);
p->p_flag &= ~(P_SA|P_HADTHREADS);
td->td_mailbox = NULL;
td->td_pflags &= ~(TDP_SA | TDP_CAN_UNBIND);
if (td->td_standin != NULL) {
thread_zombie(td->td_standin);
td->td_standin = NULL;
}
#else
p->p_flag &= ~P_HADTHREADS;
#endif
}
/*
* Called from:
* thread_exit()
*/
void
thread_unlink(struct thread *td)
{
struct proc *p = td->td_proc;
PROC_SLOCK_ASSERT(p, MA_OWNED);
TAILQ_REMOVE(&p->p_threads, td, td_plist);
p->p_numthreads--;
/* could clear a few other things here */
/* Must NOT clear links to proc! */
}
/*
* 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
* accelerated in reaching the user boundary as we will wake up
* any sleeping threads that are interruptable. (PCATCH).
*/
int
thread_single(int mode)
{
struct thread *td;
struct thread *td2;
struct proc *p;
int remaining;
td = curthread;
p = td->td_proc;
mtx_assert(&Giant, MA_NOTOWNED);
PROC_LOCK_ASSERT(p, MA_OWNED);
KASSERT((td != NULL), ("curthread is NULL"));
if ((p->p_flag & P_HADTHREADS) == 0)
return (0);
/* Is someone already single threading? */
if (p->p_singlethread != NULL && p->p_singlethread != td)
return (1);
if (mode == SINGLE_EXIT) {
p->p_flag |= P_SINGLE_EXIT;
p->p_flag &= ~P_SINGLE_BOUNDARY;
} else {
p->p_flag &= ~P_SINGLE_EXIT;
if (mode == SINGLE_BOUNDARY)
p->p_flag |= P_SINGLE_BOUNDARY;
else
p->p_flag &= ~P_SINGLE_BOUNDARY;
}
p->p_flag |= P_STOPPED_SINGLE;
PROC_SLOCK(p);
p->p_singlethread = td;
if (mode == SINGLE_EXIT)
remaining = p->p_numthreads;
else if (mode == SINGLE_BOUNDARY)
remaining = p->p_numthreads - p->p_boundary_count;
else
remaining = p->p_numthreads - p->p_suspcount;
while (remaining != 1) {
if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE)
goto stopme;
FOREACH_THREAD_IN_PROC(p, td2) {
if (td2 == td)
continue;
thread_lock(td2);
td2->td_flags |= TDF_ASTPENDING;
if (TD_IS_INHIBITED(td2)) {
switch (mode) {
case SINGLE_EXIT:
if (td->td_flags & TDF_DBSUSPEND)
td->td_flags &= ~TDF_DBSUSPEND;
if (TD_IS_SUSPENDED(td2))
thread_unsuspend_one(td2);
if (TD_ON_SLEEPQ(td2) &&
(td2->td_flags & TDF_SINTR))
sleepq_abort(td2, EINTR);
break;
case SINGLE_BOUNDARY:
break;
default:
if (TD_IS_SUSPENDED(td2)) {
thread_unlock(td2);
continue;
}
/*
* maybe other inhibited states too?
*/
if ((td2->td_flags & TDF_SINTR) &&
(td2->td_inhibitors &
(TDI_SLEEPING | TDI_SWAPPED)))
thread_suspend_one(td2);
break;
}
}
#ifdef SMP
else if (TD_IS_RUNNING(td2) && td != td2) {
forward_signal(td2);
}
#endif
thread_unlock(td2);
}
if (mode == SINGLE_EXIT)
remaining = p->p_numthreads;
else if (mode == SINGLE_BOUNDARY)
remaining = p->p_numthreads - p->p_boundary_count;
else
remaining = p->p_numthreads - p->p_suspcount;
/*
* Maybe we suspended some threads.. was it enough?
*/
if (remaining == 1)
break;
stopme:
/*
* Wake us up when everyone else has suspended.
* In the mean time we suspend as well.
*/
thread_suspend_switch(td);
if (mode == SINGLE_EXIT)
remaining = p->p_numthreads;
else if (mode == SINGLE_BOUNDARY)
remaining = p->p_numthreads - p->p_boundary_count;
else
remaining = p->p_numthreads - p->p_suspcount;
}
if (mode == SINGLE_EXIT) {
/*
* We have gotten rid of all the other threads and we
* are about to either exit or exec. In either case,
* we try our utmost to revert to being a non-threaded
* process.
*/
p->p_singlethread = NULL;
p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT);
thread_unthread(td);
}
PROC_SUNLOCK(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;
struct proc *p;
td = curthread;
p = td->td_proc;
mtx_assert(&Giant, MA_NOTOWNED);
PROC_LOCK_ASSERT(p, MA_OWNED);
while (P_SHOULDSTOP(p) ||
((p->p_flag & P_TRACED) && (td->td_flags & TDF_DBSUSPEND))) {
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 ((p->p_flag & P_SINGLE_EXIT) && return_instead)
return (EINTR);
/* Should we goto user boundary if we didn't come from there? */
if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
(p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
return (ERESTART);
/* If thread will exit, flush its pending signals */
if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td))
sigqueue_flush(&td->td_sigqueue);
PROC_SLOCK(p);
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))
thread_exit();
if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
if (p->p_numthreads == p->p_suspcount + 1) {
thread_lock(p->p_singlethread);
thread_unsuspend_one(p->p_singlethread);
thread_unlock(p->p_singlethread);
}
}
PROC_UNLOCK(p);
thread_lock(td);
/*
* When a thread suspends, it just
* gets taken off all queues.
*/
thread_suspend_one(td);
if (return_instead == 0) {
p->p_boundary_count++;
td->td_flags |= TDF_BOUNDARY;
}
PROC_SUNLOCK(p);
mi_switch(SW_INVOL, NULL);
if (return_instead == 0)
td->td_flags &= ~TDF_BOUNDARY;
thread_unlock(td);
PROC_LOCK(p);
if (return_instead == 0)
p->p_boundary_count--;
}
return (0);
}
void
thread_suspend_switch(struct thread *td)
{
struct proc *p;
p = td->td_proc;
KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
PROC_LOCK_ASSERT(p, MA_OWNED);
PROC_SLOCK_ASSERT(p, MA_OWNED);
/*
* We implement thread_suspend_one in stages here to avoid
* dropping the proc lock while the thread lock is owned.
*/
thread_stopped(p);
p->p_suspcount++;
PROC_UNLOCK(p);
thread_lock(td);
sched_sleep(td);
TD_SET_SUSPENDED(td);
PROC_SUNLOCK(p);
DROP_GIANT();
mi_switch(SW_VOL, NULL);
thread_unlock(td);
PICKUP_GIANT();
PROC_LOCK(p);
PROC_SLOCK(p);
}
void
thread_suspend_one(struct thread *td)
{
struct proc *p = td->td_proc;
PROC_SLOCK_ASSERT(p, MA_OWNED);
THREAD_LOCK_ASSERT(td, MA_OWNED);
KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
p->p_suspcount++;
sched_sleep(td);
TD_SET_SUSPENDED(td);
}
void
thread_unsuspend_one(struct thread *td)
{
struct proc *p = td->td_proc;
PROC_SLOCK_ASSERT(p, MA_OWNED);
THREAD_LOCK_ASSERT(td, MA_OWNED);
KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
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;
PROC_LOCK_ASSERT(p, MA_OWNED);
PROC_SLOCK_ASSERT(p, MA_OWNED);
if (!P_SHOULDSTOP(p)) {
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
if (TD_IS_SUSPENDED(td)) {
thread_unsuspend_one(td);
}
thread_unlock(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_lock(p->p_singlethread);
thread_unsuspend_one(p->p_singlethread);
thread_unlock(p->p_singlethread);
}
}
/*
* End the single threading mode..
*/
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_SINGLE_EXIT | P_SINGLE_BOUNDARY);
PROC_SLOCK(p);
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))) {
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
if (TD_IS_SUSPENDED(td)) {
thread_unsuspend_one(td);
}
thread_unlock(td);
}
}
PROC_SUNLOCK(p);
}
struct thread *
thread_find(struct proc *p, lwpid_t tid)
{
struct thread *td;
PROC_LOCK_ASSERT(p, MA_OWNED);
PROC_SLOCK(p);
FOREACH_THREAD_IN_PROC(p, td) {
if (td->td_tid == tid)
break;
}
PROC_SUNLOCK(p);
return (td);
}