198 lines
3.9 KiB
C
198 lines
3.9 KiB
C
/*
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* This file is part of the UCB release of Plan 9. It is subject to the license
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* terms in the LICENSE file found in the top-level directory of this
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* distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
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* part of the UCB release of Plan 9, including this file, may be copied,
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* modified, propagated, or distributed except according to the terms contained
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* in the LICENSE file.
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*/
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#include <u.h>
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#include <libc.h>
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#include <thread.h>
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#include "threadimpl.h"
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static Thread *runthread(Proc*);
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static char *_psstate[] = {
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"Moribund",
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"Dead",
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"Exec",
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"Fork",
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"Running",
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"Ready",
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"Rendezvous",
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};
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static char*
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psstate(int s)
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{
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if(s < 0 || s >= nelem(_psstate))
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return "unknown";
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return _psstate[s];
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}
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void
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_schedinit(void *arg)
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{
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Proc *p;
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Thread *t, **l;
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p = arg;
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_threadsetproc(p);
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p->pid = jehanne_getpid();
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while(jehanne_setjmp(p->sched))
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;
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_threaddebug(DBGSCHED, "top of schedinit, _threadexitsallstatus=%p", _threadexitsallstatus);
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if(_threadexitsallstatus)
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jehanne_exits(_threadexitsallstatus);
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jehanne_lock(&p->lock);
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if((t=p->thread) != nil){
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p->thread = nil;
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if(t->moribund){
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t->state = Dead;
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for(l=&p->threads.head; *l; l=&(*l)->nextt)
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if(*l == t){
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*l = t->nextt;
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if(*l==nil)
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p->threads.tail = l;
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p->nthreads--;
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break;
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}
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jehanne_unlock(&p->lock);
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if(t->inrendez){
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_threadflagrendez(t);
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_threadbreakrendez();
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}
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jehanne_free(t->stk);
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jehanne_free(t->cmdname);
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jehanne_free(t); /* XXX how do we know there are no references? */
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t = nil;
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_sched();
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}
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if(p->needexec){
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t->ret = _schedexec(&p->exec);
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p->needexec = 0;
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}
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if(p->newproc){
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t->ret = _schedfork(p->newproc);
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p->newproc = nil;
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}
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t->state = t->nextstate;
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if(t->state == Ready)
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_threadready(t);
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}
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jehanne_unlock(&p->lock);
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_sched();
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}
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void
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needstack(int n)
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{
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int x;
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Proc *p;
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Thread *t;
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p = _threadgetproc();
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t = p->thread;
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if((uint8_t*)&x - n < (uint8_t*)t->stk){
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jehanne_fprint(2, "%s %lud: &x=%p n=%d t->stk=%p\n",
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argv0, jehanne_getpid(), &x, n, t->stk);
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jehanne_fprint(2, "%s %lud: stack overflow\n", argv0, jehanne_getmainpid());
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abort();
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}
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}
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void
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_sched(void)
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{
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Proc *p;
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Thread *t;
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Resched:
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p = _threadgetproc();
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if((t = p->thread) != nil){
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needstack(128);
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_threaddebug(DBGSCHED, "pausing, state=%s", psstate(t->state));
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if(jehanne_setjmp(t->sched)==0)
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jehanne_longjmp(p->sched, 1);
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return;
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}else{
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t = runthread(p);
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if(t == nil){
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_threaddebug(DBGSCHED, "all threads gone; exiting");
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_schedexit(p);
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}
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_threaddebug(DBGSCHED, "running %d.%d", t->proc->pid, t->id);
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p->thread = t;
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if(t->moribund){
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_threaddebug(DBGSCHED, "%d.%d marked to die");
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goto Resched;
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}
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t->state = Running;
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t->nextstate = Ready;
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jehanne_longjmp(t->sched, 1);
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}
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}
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static Thread*
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runthread(Proc *p)
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{
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Thread *t;
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Tqueue *q;
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if(p->nthreads==0)
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return nil;
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q = &p->ready;
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jehanne_lock(&p->readylock);
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if(q->head == nil){
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q->asleep = 1;
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_threaddebug(DBGSCHED, "sleeping for more work");
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jehanne_unlock(&p->readylock);
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while(sys_rendezvous(q, 0) == (void*)~0){
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if(_threadexitsallstatus)
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jehanne_exits(_threadexitsallstatus);
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}
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/* lock picked up from _threadready */
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}
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t = q->head;
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q->head = t->next;
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jehanne_unlock(&p->readylock);
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return t;
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}
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void
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_threadready(Thread *t)
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{
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Tqueue *q;
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assert(t->state == Ready);
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_threaddebug(DBGSCHED, "readying %d.%d", t->proc->pid, t->id);
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q = &t->proc->ready;
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jehanne_lock(&t->proc->readylock);
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t->next = nil;
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if(q->head==nil)
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q->head = t;
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else
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*q->tail = t;
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q->tail = &t->next;
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if(q->asleep){
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q->asleep = 0;
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/* lock passes to runthread */
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_threaddebug(DBGSCHED, "waking process %d", t->proc->pid);
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while(sys_rendezvous(q, 0) == (void*)~0){
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if(_threadexitsallstatus)
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jehanne_exits(_threadexitsallstatus);
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}
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}else
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jehanne_unlock(&t->proc->readylock);
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}
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void
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yield(void)
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{
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_sched();
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}
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