/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include <thread.h>#include "threadimpl.h"#include <tos.h> static Thread	*runthread(Proc*); static char *_psstate[] = {	"Moribund",	"Dead",	"Exec",	"Fork",	"Running",	"Ready",	"Rendezvous",}; static char*psstate(int s){	if(s < 0 || s >= nelem(_psstate))		return "unknown";	return _psstate[s];} void_schedinit(void *arg){	Proc *p;	Thread *t, **l; 	p = arg;	_threadsetproc(p);	p->pid = _tos->pid; //getpid();	while(setjmp(p->sched))		;	_threaddebug(DBGSCHED, "top of schedinit, _threadexitsallstatus=%p", _threadexitsallstatus);	if(_threadexitsallstatus)		exits(_threadexitsallstatus);	lock(&p->lock);	if((t=p->thread) != nil){		p->thread = nil;		if(t->moribund){			t->state = Dead;			for(l=&p->threads.head; *l; l=&(*l)->nextt)				if(*l == t){					*l = t->nextt;					if(*l==nil)						p->threads.tail = l;					p->nthreads--;					break;				}			unlock(&p->lock);			if(t->inrendez){				_threadflagrendez(t);				_threadbreakrendez();			}			free(t->stk);			free(t->cmdname);			free(t);	/* XXX how do we know there are no references? */			t = nil;			_sched();		}		if(p->needexec){			t->ret = _schedexec(&p->exec);			p->needexec = 0;		}		if(p->newproc){			t->ret = _schedfork(p->newproc);			p->newproc = nil;		}		t->state = t->nextstate;		if(t->state == Ready)			_threadready(t);	}	unlock(&p->lock);	_sched();} voidneedstack(int n){	int x;	Proc *p;	Thread *t;		p = _threadgetproc();	t = p->thread;		if((uchar*)&x - n < (uchar*)t->stk){		fprint(2, "%s %lud: &x=%p n=%d t->stk=%p\n",			argv0, _tos->pid, &x, n, t->stk);		fprint(2, "%s %lud: stack overflow\n", argv0, _tos->pid);		abort();	}} void_sched(void){	Proc *p;	Thread *t; Resched:	p = _threadgetproc();	if((t = p->thread) != nil){		needstack(128);		_threaddebug(DBGSCHED, "pausing, state=%s", psstate(t->state));		if(setjmp(t->sched)==0)			longjmp(p->sched, 1);		return;	}else{		t = runthread(p);		if(t == nil){			_threaddebug(DBGSCHED, "all threads gone; exiting");			_schedexit(p);		}		_threaddebug(DBGSCHED, "running %d.%d", t->proc->pid, t->id);		p->thread = t;		if(t->moribund){			_threaddebug(DBGSCHED, "%d.%d marked to die");			goto Resched;		}		t->state = Running;		t->nextstate = Ready;		longjmp(t->sched, 1);	}} static Thread*runthread(Proc *p){	Thread *t;	Tqueue *q; 	if(p->nthreads==0)		return nil;	q = &p->ready;	lock(&p->readylock);	if(q->head == nil){		q->asleep = 1;		_threaddebug(DBGSCHED, "sleeping for more work");		unlock(&p->readylock);		while(rendezvous(q, 0) == (void*)~0){			if(_threadexitsallstatus)				exits(_threadexitsallstatus);		}		/* lock picked up from _threadready */	}	t = q->head;	q->head = t->next;	unlock(&p->readylock);	return t;} void_threadready(Thread *t){	Tqueue *q; 	assert(t->state == Ready);	_threaddebug(DBGSCHED, "readying %d.%d", t->proc->pid, t->id);	q = &t->proc->ready;	lock(&t->proc->readylock);	t->next = nil;	if(q->head==nil)		q->head = t;	else		*q->tail = t;	q->tail = &t->next;	if(q->asleep){		q->asleep = 0;		/* lock passes to runthread */		_threaddebug(DBGSCHED, "waking process %d", t->proc->pid);		while(rendezvous(q, 0) == (void*)~0){			if(_threadexitsallstatus)				exits(_threadexitsallstatus);		}	}else		unlock(&t->proc->readylock);} voidyield(void){	_sched();}