1 #include "threadimpl.h"
2 
3 int	_threaddebuglevel;
4 
5 static	uint		threadnproc;
6 static	uint		threadnsysproc;
7 static	Lock		threadnproclock;
8 static	Ref		threadidref;
9 static	Proc		*threadmainproc;
10 
11 static	void		addproc(Proc*);
12 static	void		delproc(Proc*);
13 static	void		addthread(_Threadlist*, _Thread*);
14 static	void		delthread(_Threadlist*, _Thread*);
15 static	void		addthreadinproc(Proc*, _Thread*);
16 static	void		delthreadinproc(Proc*, _Thread*);
17 static	void		contextswitch(Context *from, Context *to);
18 static	void		procscheduler(Proc*);
19 
20 static void
21 _threaddebug(char *fmt, ...)
22 {
23 	va_list arg;
24 	char buf[128];
25 	_Thread *t;
26 	char *p;
27 	static int fd = -1;
28 
29 return;
30 	va_start(arg, fmt);
31 	vfprint(1, fmt, arg);
32 	va_end(arg);
33 return;
34 
35 	if(fd < 0){
36 		p = strrchr(argv0, '/');
37 		if(p)
38 			p++;
39 		else
40 			p = argv0;
41 		snprint(buf, sizeof buf, "/tmp/%s.tlog", p);
42 		if((fd = create(buf, OWRITE, 0666)) < 0)
43 			fd = open("/dev/null", OWRITE);
44 	}
45 
46 	va_start(arg, fmt);
47 	vsnprint(buf, sizeof buf, fmt, arg);
48 	va_end(arg);
49 	t = proc()->thread;
50 	if(t)
51 		fprint(fd, "%d.%d: %s\n", getpid(), t->id, buf);
52 	else
53 		fprint(fd, "%d._: %s\n", getpid(), buf);
54 }
55 
56 static _Thread*
57 getthreadnow(void)
58 {
59 	return proc()->thread;
60 }
61 _Thread	*(*threadnow)(void) = getthreadnow;
62 
63 static Proc*
64 procalloc(void)
65 {
66 	Proc *p;
67 
68 	p = malloc(sizeof *p);
69 	if(p == nil)
70 		sysfatal("procalloc malloc: %r");
71 	memset(p, 0, sizeof *p);
72 	addproc(p);
73 	lock(&threadnproclock);
74 	threadnproc++;
75 	unlock(&threadnproclock);
76 	return p;
77 }
78 
79 static void
80 threadstart(uint y, uint x)
81 {
82 	_Thread *t;
83 	ulong z;
84 
85 	z = x<<16;	/* hide undefined 32-bit shift from 32-bit compilers */
86 	z <<= 16;
87 	z |= y;
88 	t = (_Thread*)z;
89 
90 //print("threadstart %p\n", v);
91 	t->startfn(t->startarg);
92 //print("threadexits %p\n", v);
93 	threadexits(nil);
94 //print("not reacehd\n");
95 }
96 
97 static _Thread*
98 threadalloc(void (*fn)(void*), void *arg, uint stack)
99 {
100 	_Thread *t;
101 	sigset_t zero;
102 	uint x, y;
103 	ulong z;
104 
105 	/* allocate the task and stack together */
106 	t = malloc(sizeof *t+stack);
107 	if(t == nil)
108 		sysfatal("threadalloc malloc: %r");
109 	memset(t, 0, sizeof *t);
110 	t->stk = (uchar*)(t+1);
111 	t->stksize = stack;
112 	t->id = incref(&threadidref);
113 	t->startfn = fn;
114 	t->startarg = arg;
115 
116 	/* do a reasonable initialization */
117 	memset(&t->context.uc, 0, sizeof t->context.uc);
118 	sigemptyset(&zero);
119 	sigprocmask(SIG_BLOCK, &zero, &t->context.uc.uc_sigmask);
120 
121 	/* must initialize with current context */
122 	if(getcontext(&t->context.uc) < 0)
123 		sysfatal("threadalloc getcontext: %r");
124 
125 	/* call makecontext to do the real work. */
126 	/* leave a few words open on both ends */
127 	t->context.uc.uc_stack.ss_sp = t->stk+8;
128 	t->context.uc.uc_stack.ss_size = t->stksize-64;
129 #ifdef __sun__		/* sigh */
130 	/* can avoid this with __MAKECONTEXT_V2_SOURCE but only on SunOS 5.9 */
131 	t->context.uc.uc_stack.ss_sp = 
132 		(char*)t->context.uc.uc_stack.ss_sp
133 		+t->context.uc.uc_stack.ss_size;
134 #endif
135 	/*
136 	 * All this magic is because you have to pass makecontext a
137 	 * function that takes some number of word-sized variables,
138 	 * and on 64-bit machines pointers are bigger than words.
139 	 */
140 	z = (ulong)t;
141 	y = z;
142 	z >>= 16;	/* hide undefined 32-bit shift from 32-bit compilers */
143 	x = z>>16;
144 	makecontext(&t->context.uc, (void(*)())threadstart, 2, y, x);
145 
146 	return t;
147 }
148 
149 _Thread*
150 _threadcreate(Proc *p, void (*fn)(void*), void *arg, uint stack)
151 {
152 	_Thread *t;
153 
154 	t = threadalloc(fn, arg, stack);
155 	t->proc = p;
156 	addthreadinproc(p, t);
157 	p->nthread++;
158 	_threadready(t);
159 	return t;
160 }
161 
162 int
163 threadcreate(void (*fn)(void*), void *arg, uint stack)
164 {
165 	_Thread *t;
166 
167 	t = _threadcreate(proc(), fn, arg, stack);
168 	return t->id;
169 }
170 
171 int
172 proccreate(void (*fn)(void*), void *arg, uint stack)
173 {
174 	int id;
175 	_Thread *t;
176 	Proc *p;
177 
178 	p = procalloc();
179 	t = _threadcreate(p, fn, arg, stack);
180 	id = t->id;	/* t might be freed after _procstart */
181 	_procstart(p, procscheduler);
182 	return id;
183 }
184 
185 void
186 _threadswitch(void)
187 {
188 	Proc *p;
189 
190 	needstack(0);
191 	p = proc();
192 //print("threadswtch %p\n", p);
193 	contextswitch(&p->thread->context, &p->schedcontext);
194 }
195 
196 void
197 _threadready(_Thread *t)
198 {
199 	Proc *p;
200 
201 	p = t->proc;
202 	lock(&p->lock);
203 	p->runrend.l = &p->lock;
204 	addthread(&p->runqueue, t);
205 //print("%d wake for job %d->%d\n", time(0), getpid(), p->osprocid);
206 	if(p != proc())
207 		_procwakeupandunlock(&p->runrend);
208 	else
209 		unlock(&p->lock);
210 }
211 
212 int
213 threadyield(void)
214 {
215 	int n;
216 	Proc *p;
217 
218 	p = proc();
219 	n = p->nswitch;
220 	_threadready(p->thread);
221 	_threadswitch();
222 	return p->nswitch - n;
223 }
224 
225 void
226 threadexits(char *msg)
227 {
228 	Proc *p;
229 
230 	p = proc();
231 	if(msg == nil)
232 		msg = "";
233 	utfecpy(p->msg, p->msg+sizeof p->msg, msg);
234 	proc()->thread->exiting = 1;
235 	_threadswitch();
236 }
237 
238 static void
239 contextswitch(Context *from, Context *to)
240 {
241 	if(swapcontext(&from->uc, &to->uc) < 0){
242 		fprint(2, "swapcontext failed: %r\n");
243 		assert(0);
244 	}
245 }
246 
247 static void
248 procscheduler(Proc *p)
249 {
250 	_Thread *t;
251 
252 	setproc(p);
253 	_threaddebug("scheduler enter");
254 //	print("s %p\n", p);
255 	lock(&p->lock);
256 	for(;;){
257 		while((t = p->runqueue.head) == nil){
258 			if(p->nthread == 0)
259 				goto Out;
260 			p->runrend.l = &p->lock;
261 			_threaddebug("scheduler sleep");
262 			_procsleep(&p->runrend);
263 			_threaddebug("scheduler wake");
264 		}
265 		delthread(&p->runqueue, t);
266 		unlock(&p->lock);
267 		p->thread = t;
268 		p->nswitch++;
269 		_threaddebug("run %d (%s)", t->id, t->name);
270 		contextswitch(&p->schedcontext, &t->context);
271 //print("back in scheduler\n");
272 		p->thread = nil;
273 		lock(&p->lock);
274 		if(t->exiting){
275 			delthreadinproc(p, t);
276 			p->nthread--;
277 //print("ntrhead %d\n", p->nthread);
278 			free(t);
279 		}
280 	}
281 
282 Out:
283 	_threaddebug("scheduler exit");
284 	if(p->mainproc){
285 		/*
286 		 * Stupid bug - on Linux 2.6 and maybe elsewhere,
287 		 * if the main thread exits then the others keep running
288 		 * but the process shows up as a zombie in ps and is not
289 		 * attachable with ptrace.  We'll just sit around pretending
290 		 * to be a system proc instead of exiting.
291 		 */
292 		_threaddaemonize();
293 		lock(&threadnproclock);
294 		if(++threadnsysproc == threadnproc)
295 			threadexitsall(p->msg);
296 		p->sysproc = 1;
297 		unlock(&threadnproclock);
298 		for(;;)
299 		 	sleep(1000);
300 	}
301 
302 	delproc(p);
303 	lock(&threadnproclock);
304 	if(p->sysproc)
305 		--threadnsysproc;
306 	if(--threadnproc == threadnsysproc)
307 		threadexitsall(p->msg);
308 	unlock(&threadnproclock);
309 	unlock(&p->lock);
310 	free(p);
311 	setproc(0);
312 }
313 
314 void
315 _threadsetsysproc(void)
316 {
317 	lock(&threadnproclock);
318 	if(++threadnsysproc == threadnproc)
319 		threadexitsall(nil);
320 	unlock(&threadnproclock);
321 	proc()->sysproc = 1;
322 }
323 
324 void**
325 procdata(void)
326 {
327 	return &proc()->udata;
328 }
329 
330 extern Jmp *(*_notejmpbuf)(void);
331 static Jmp*
332 threadnotejmp(void)
333 {
334 	return &proc()->sigjmp;
335 }
336 
337 /*
338  * debugging
339  */
340 void
341 threadsetname(char *fmt, ...)
342 {
343 	va_list arg;
344 	_Thread *t;
345 
346 	t = proc()->thread;
347 	va_start(arg, fmt);
348 	vsnprint(t->name, sizeof t->name, fmt, arg);
349 	va_end(arg);
350 }
351 
352 char*
353 threadgetname(void)
354 {
355 	return proc()->thread->name;
356 }
357 
358 void
359 threadsetstate(char *fmt, ...)
360 {
361 	va_list arg;
362 	_Thread *t;
363 
364 	t = proc()->thread;
365 	va_start(arg, fmt);
366 	vsnprint(t->state, sizeof t->name, fmt, arg);
367 	va_end(arg);
368 }
369 
370 void
371 needstack(int n)
372 {
373 	_Thread *t;
374 
375 	t = proc()->thread;
376 
377 	if((char*)&t <= (char*)t->stk
378 	|| (char*)&t - (char*)t->stk < 256+n){
379 		fprint(2, "thread stack overflow: &t=%p tstk=%p n=%d\n", &t, t->stk, 256+n);
380 		abort();
381 	}
382 }
383 
384 /*
385  * locking
386  */
387 static int
388 threadqlock(QLock *l, int block, ulong pc)
389 {
390 //print("threadqlock %p\n", l);
391 	lock(&l->l);
392 	if(l->owner == nil){
393 		l->owner = (*threadnow)();
394 //print("qlock %p @%#x by %p\n", l, pc, l->owner);
395 		unlock(&l->l);
396 		return 1;
397 	}
398 	if(!block){
399 		unlock(&l->l);
400 		return 0;
401 	}
402 //print("qsleep %p @%#x by %p\n", l, pc, (*threadnow)());
403 	addthread(&l->waiting, (*threadnow)());
404 	unlock(&l->l);
405 
406 	_threadswitch();
407 
408 	if(l->owner != (*threadnow)()){
409 		fprint(2, "%s: qlock pc=0x%lux owner=%p self=%p oops\n",
410 			argv0, pc, l->owner, (*threadnow)());
411 		abort();
412 	}
413 //print("qlock wakeup %p @%#x by %p\n", l, pc, (*threadnow)());
414 	return 1;
415 }
416 
417 static void
418 threadqunlock(QLock *l, ulong pc)
419 {
420 	_Thread *ready;
421 	
422 	lock(&l->l);
423 //print("qlock unlock %p @%#x by %p (owner %p)\n", l, pc, (*threadnow)(), l->owner);
424 	if(l->owner == 0){
425 		fprint(2, "%s: qunlock pc=0x%lux owner=%p self=%p oops\n",
426 			argv0, pc, l->owner, (*threadnow)());
427 		abort();
428 	}
429 	if((l->owner = ready = l->waiting.head) != nil)
430 		delthread(&l->waiting, l->owner);
431 	/*
432 	 * N.B. Cannot call _threadready() before unlocking l->l,
433 	 * because the thread we are readying might:
434 	 *	- be in another proc
435 	 *	- start running immediately
436 	 *	- and free l before we get a chance to run again
437 	 */
438 	unlock(&l->l);
439 	if(ready)
440 		_threadready(l->owner);
441 }
442 
443 static int
444 threadrlock(RWLock *l, int block, ulong pc)
445 {
446 	USED(pc);
447 
448 	lock(&l->l);
449 	if(l->writer == nil && l->wwaiting.head == nil){
450 		l->readers++;
451 		unlock(&l->l);
452 		return 1;
453 	}
454 	if(!block){
455 		unlock(&l->l);
456 		return 0;
457 	}
458 	addthread(&l->rwaiting, (*threadnow)());
459 	unlock(&l->l);
460 	_threadswitch();
461 	return 1;	
462 }
463 
464 static int
465 threadwlock(RWLock *l, int block, ulong pc)
466 {
467 	USED(pc);
468 
469 	lock(&l->l);
470 	if(l->writer == nil && l->readers == 0){
471 		l->writer = (*threadnow)();
472 		unlock(&l->l);
473 		return 1;
474 	}
475 	if(!block){
476 		unlock(&l->l);
477 		return 0;
478 	}
479 	addthread(&l->wwaiting, (*threadnow)());
480 	unlock(&l->l);
481 	_threadswitch();
482 	return 1;
483 }
484 
485 static void
486 threadrunlock(RWLock *l, ulong pc)
487 {
488 	_Thread *t;
489 
490 	USED(pc);
491 	t = nil;
492 	lock(&l->l);
493 	--l->readers;
494 	if(l->readers == 0 && (t = l->wwaiting.head) != nil){
495 		delthread(&l->wwaiting, t);
496 		l->writer = t;
497 	}
498 	unlock(&l->l);
499 	if(t)
500 		_threadready(t);
501 
502 }
503 
504 static void
505 threadwunlock(RWLock *l, ulong pc)
506 {
507 	_Thread *t;
508 
509 	USED(pc);
510 	lock(&l->l);
511 	l->writer = nil;
512 	assert(l->readers == 0);
513 	while((t = l->rwaiting.head) != nil){
514 		delthread(&l->rwaiting, t);
515 		l->readers++;
516 		_threadready(t);
517 	}
518 	t = nil;
519 	if(l->readers == 0 && (t = l->wwaiting.head) != nil){
520 		delthread(&l->wwaiting, t);
521 		l->writer = t;
522 	}
523 	unlock(&l->l);
524 	if(t)
525 		_threadready(t);
526 }
527 
528 /*
529  * sleep and wakeup
530  */
531 static void
532 threadrsleep(Rendez *r, ulong pc)
533 {
534 	addthread(&r->waiting, proc()->thread);
535 	qunlock(r->l);
536 	_threadswitch();
537 	qlock(r->l);
538 }
539 
540 static int
541 threadrwakeup(Rendez *r, int all, ulong pc)
542 {
543 	int i;
544 	_Thread *t;
545 
546 	for(i=0;; i++){
547 		if(i==1 && !all)
548 			break;
549 		if((t = r->waiting.head) == nil)
550 			break;
551 		delthread(&r->waiting, t);
552 		_threadready(t);	
553 	}
554 	return i;
555 }
556 
557 /*
558  * startup
559  */
560 
561 static int threadargc;
562 static char **threadargv;
563 int mainstacksize;
564 
565 static void
566 threadmainstart(void *v)
567 {
568 	USED(v);
569 
570 	/*
571 	 * N.B. This call to proc() is a program's first call (indirectly) to a
572 	 * pthreads function while executing on a non-pthreads-allocated
573 	 * stack.  If the pthreads implementation is using the stack pointer
574 	 * to locate the per-thread data, then this call will blow up.
575 	 * This means the pthread implementation is not suitable for
576 	 * running under libthread.  Time to write your own.  Sorry.
577 	 */
578 	threadmainproc = proc();
579 	threadmain(threadargc, threadargv);
580 }
581 
582 int
583 main(int argc, char **argv)
584 {
585 	Proc *p;
586 
587 	argv0 = argv[0];
588 
589 	_threadsetupdaemonize();
590 
591 	threadargc = argc;
592 	threadargv = argv;
593 
594 	/*
595 	 * Install locking routines into C library.
596 	 */
597 	_lock = _threadlock;
598 	_unlock = _threadunlock;
599 	_qlock = threadqlock;
600 	_qunlock = threadqunlock;
601 	_rlock = threadrlock;
602 	_runlock = threadrunlock;
603 	_wlock = threadwlock;
604 	_wunlock = threadwunlock;
605 	_rsleep = threadrsleep;
606 	_rwakeup = threadrwakeup;
607 	_notejmpbuf = threadnotejmp;
608 
609 	_pthreadinit();
610 	p = procalloc();
611 	p->mainproc = 1;
612 	_threadsetproc(p);
613 	if(mainstacksize == 0)
614 		mainstacksize = 256*1024;
615 	_threadcreate(p, threadmainstart, nil, mainstacksize);
616 	procscheduler(p);
617 	sysfatal("procscheduler returned in threadmain!");
618 	/* does not return */
619 	return 0;
620 }
621 
622 /*
623  * hooray for linked lists
624  */
625 static void
626 addthread(_Threadlist *l, _Thread *t)
627 {
628 	if(l->tail){
629 		l->tail->next = t;
630 		t->prev = l->tail;
631 	}else{
632 		l->head = t;
633 		t->prev = nil;
634 	}
635 	l->tail = t;
636 	t->next = nil;
637 }
638 
639 static void
640 delthread(_Threadlist *l, _Thread *t)
641 {
642 	if(t->prev)
643 		t->prev->next = t->next;
644 	else
645 		l->head = t->next;
646 	if(t->next)
647 		t->next->prev = t->prev;
648 	else
649 		l->tail = t->prev;
650 }
651 
652 static void
653 addthreadinproc(Proc *p, _Thread *t)
654 {
655 	_Threadlist *l;
656 
657 	l = &p->allthreads;
658 	if(l->tail){
659 		l->tail->allnext = t;
660 		t->allprev = l->tail;
661 	}else{
662 		l->head = t;
663 		t->allprev = nil;
664 	}
665 	l->tail = t;
666 	t->allnext = nil;
667 }
668 
669 static void
670 delthreadinproc(Proc *p, _Thread *t)
671 {
672 	_Threadlist *l;
673 
674 	l = &p->allthreads;
675 	if(t->allprev)
676 		t->allprev->allnext = t->allnext;
677 	else
678 		l->head = t->allnext;
679 	if(t->allnext)
680 		t->allnext->allprev = t->allprev;
681 	else
682 		l->tail = t->allprev;
683 }
684 
685 Proc *_threadprocs;
686 Lock _threadprocslock;
687 static Proc *_threadprocstail;
688 
689 static void
690 addproc(Proc *p)
691 {
692 	lock(&_threadprocslock);
693 	if(_threadprocstail){
694 		_threadprocstail->next = p;
695 		p->prev = _threadprocstail;
696 	}else{
697 		_threadprocs = p;
698 		p->prev = nil;
699 	}
700 	_threadprocstail = p;
701 	p->next = nil;
702 	unlock(&_threadprocslock);
703 }
704 
705 static void
706 delproc(Proc *p)
707 {
708 	lock(&_threadprocslock);
709 	if(p->prev)
710 		p->prev->next = p->next;
711 	else
712 		_threadprocs = p->next;
713 	if(p->next)
714 		p->next->prev = p->prev;
715 	else
716 		_threadprocstail = p->prev;
717 	unlock(&_threadprocslock);
718 }
719 
720 /* 
721  * notify - for now just use the usual mechanisms
722  */
723 void
724 threadnotify(int (*f)(void*, char*), int in)
725 {
726 	atnotify(f, in);
727 }