1 #include "threadimpl.h"
2 
3 extern int __isthreaded;
4 
5 /*
6  * spin locks
7  */
8 extern int _tas(int*);
9 
10 void
11 _threadunlock(Lock *l, ulong pc)
12 {
13 	USED(pc);
14 
15 	l->held = 0;
16 }
17 
18 int
19 _threadlock(Lock *l, int block, ulong pc)
20 {
21 	int i;
22 
23 	USED(pc);
24 
25 	/* once fast */
26 	if(!_tas(&l->held))
27 		return 1;
28 	if(!block)
29 		return 0;
30 
31 	/* a thousand times pretty fast */
32 	for(i=0; i<1000; i++){
33 		if(!_tas(&l->held))
34 			return 1;
35 		sched_yield();
36 	}
37 	/* now nice and slow */
38 	for(i=0; i<1000; i++){
39 		if(!_tas(&l->held))
40 			return 1;
41 		usleep(100*1000);
42 	}
43 	/* take your time */
44 	while(_tas(&l->held))
45 		usleep(1000*1000);
46 	return 1;
47 }
48 
49 /*
50  * For FreeBSD libc.
51  */
52 
53 typedef struct {
54 	volatile long	access_lock;
55 	volatile long	lock_owner;
56 	volatile char	*fname;
57 	volatile int	lineno;
58 } spinlock_t;
59 
60 void
61 _spinlock(spinlock_t *lk)
62 {
63 	lock((Lock*)&lk->access_lock);
64 }
65 
66 /*
67  * sleep and wakeup
68  */
69 static void
70 ign(int x)
71 {
72 	USED(x);
73 }
74 
75 static void /*__attribute__((constructor))*/
76 ignusr1(int restart)
77 {
78 	struct sigaction sa;
79 
80 	memset(&sa, 0, sizeof sa);
81 	sa.sa_handler = ign;
82 	sigemptyset(&sa.sa_mask);
83 	sigaddset(&sa.sa_mask, SIGUSR1);
84 	if(restart)
85 		sa.sa_flags = SA_RESTART;
86 	sigaction(SIGUSR1, &sa, nil);
87 }
88 
89 void
90 _procsleep(_Procrendez *r)
91 {
92 	sigset_t mask;
93 
94 	/*
95 	 * Go to sleep.
96 	 *
97 	 * Block USR1, set the handler to interrupt system calls,
98 	 * unlock the vouslock so our waker can wake us,
99 	 * and then suspend.
100 	 */
101 again:
102 	r->asleep = 1;
103 	r->pid = getpid();
104 
105 	sigprocmask(SIG_SETMASK, nil, &mask);
106 	sigaddset(&mask, SIGUSR1);
107 	sigprocmask(SIG_SETMASK, &mask, nil);
108 	ignusr1(0);
109 	unlock(r->l);
110 	sigdelset(&mask, SIGUSR1);
111 	sigsuspend(&mask);
112 
113 	/*
114 	 * We're awake.  Make USR1 not interrupt system calls.
115 	 */
116 	lock(r->l);
117 	ignusr1(1);
118 	if(r->asleep && r->pid == getpid()){
119 		/* Didn't really wake up - signal from something else */
120 		goto again;
121 	}
122 }
123 
124 void
125 _procwakeup(_Procrendez *r)
126 {
127 	if(r->asleep){
128 		r->asleep = 0;
129 		assert(r->pid >= 1);
130 		kill(r->pid, SIGUSR1);
131 	}
132 }
133 
134 /*
135  * process creation and exit
136  */
137 typedef struct Stackfree Stackfree;
138 struct Stackfree
139 {
140 	Stackfree	*next;
141 	int	pid;
142 };
143 static Lock stacklock;
144 static Stackfree *stackfree;
145 
146 static void
147 delayfreestack(uchar *stk)
148 {
149 	Stackfree *sf;
150 
151 	sf = (Stackfree*)stk;
152 	sf->pid = getpid();
153 	lock(&stacklock);
154 	sf->next = stackfree;
155 	stackfree = sf;
156 	unlock(&stacklock);
157 }
158 
159 static void
160 dofreestacks(void)
161 {
162 	Stackfree *sf, *last, *next;
163 
164 	if(stackfree==nil || !canlock(&stacklock))
165 		return;
166 
167 	for(last=nil,sf=stackfree; sf; last=sf,sf=next){
168 		next = sf->next;
169 		if(sf->pid >= 1 && kill(sf->pid, 0) < 0 && errno == ESRCH){
170 			free(sf);
171 			if(last)
172 				last->next = next;
173 			else
174 				stackfree = next;
175 			sf = last;
176 		}
177 	}
178 	unlock(&stacklock);
179 }
180 
181 static int
182 startprocfn(void *v)
183 {
184 	void **a;
185 	uchar *stk;
186 	void (*fn)(void*);
187 	Proc *p;
188 
189 	a = (void**)v;
190 	fn = a[0];
191 	p = a[1];
192 	stk = a[2];
193 	free(a);
194 	p->osprocid = getpid();
195 
196 	(*fn)(p);
197 
198 	delayfreestack(stk);
199 	_exit(0);
200 	return 0;
201 }
202 
203 void
204 _procstart(Proc *p, void (*fn)(Proc*))
205 {
206 	void **a;
207 	uchar *stk;
208 	int pid;
209 
210 	dofreestacks();
211 	a = malloc(3*sizeof a[0]);
212 	if(a == nil)
213 		sysfatal("_procstart malloc: %r");
214 	stk = malloc(65536);
215 	if(stk == nil)
216 		sysfatal("_procstart malloc stack: %r");
217 
218 	a[0] = fn;
219 	a[1] = p;
220 	a[2] = stk;
221 
222 	pid = rfork_thread(RFPROC|RFMEM|RFNOWAIT, stk+65536-64, startprocfn, a);
223 	if(pid < 0){
224 		fprint(2, "_procstart rfork_thread: %r\n");
225 		abort();
226 	}
227 }
228 
229 static char *threadexitsmsg;
230 void
231 sigusr2handler(int s)
232 {
233 /*	fprint(2, "%d usr2 %d\n", time(0), getpid()); */
234 	if(threadexitsmsg)
235 		_exits(threadexitsmsg);
236 }
237 
238 void
239 threadexitsall(char *msg)
240 {
241 	static int pid[1024];
242 	int i, npid, mypid;
243 	Proc *p;
244 
245 	if(msg == nil)
246 		msg = "";
247 	mypid = getpid();
248 	lock(&_threadprocslock);
249 	threadexitsmsg = msg;
250 	npid = 0;
251 	for(p=_threadprocs; p; p=p->next)
252 		if(p->osprocid != mypid && p->osprocid >= 1)
253 			pid[npid++] = p->osprocid;
254 	for(i=0; i<npid; i++)
255 		kill(pid[i], SIGUSR2);
256 	unlock(&_threadprocslock);
257 	exits(msg);
258 }
259 
260 /*
261  * per-process data, indexed by pid
262  *
263  * could use modify_ldt and a segment register
264  * to avoid the many calls to getpid(), but i don't
265  * care -- this is compatibility code.  linux 2.6 with
266  * nptl is a good enough pthreads to avoid this whole file.
267  */
268 typedef struct Perproc Perproc;
269 struct Perproc
270 {
271 	int		pid;
272 	Proc	*proc;
273 };
274 
275 static Lock perlock;
276 static Perproc perproc[1024];
277 #define P ((Proc*)-1)
278 
279 static Perproc*
280 myperproc(void)
281 {
282 	int i, pid, h;
283 	Perproc *p;
284 
285 	pid = getpid();
286 	h = pid%nelem(perproc);
287 	for(i=0; i<nelem(perproc); i++){
288 		p = &perproc[(i+h)%nelem(perproc)];
289 		if(p->pid == pid)
290 			return p;
291 		if(p->pid == 0){
292 			print("found 0 at %d (h=%d)\n", (i+h)%nelem(perproc), h);
293 			break;
294 		}
295 	}
296 	fprint(2, "myperproc %d: cannot find self\n", pid);
297 	abort();
298 	return nil;
299 }
300 
301 static Perproc*
302 newperproc(void)
303 {
304 	int i, pid, h;
305 	Perproc *p;
306 
307 	lock(&perlock);
308 	pid = getpid();
309 	h = pid%nelem(perproc);
310 	for(i=0; i<nelem(perproc); i++){
311 		p = &perproc[(i+h)%nelem(perproc)];
312 		if(p->pid == pid || p->pid == -1 || p->pid == 0){
313 			p->pid = pid;
314 			unlock(&perlock);
315 			return p;
316 		}
317 	}
318 	fprint(2, "newperproc %d: out of procs\n", pid);
319 	abort();
320 	return nil;
321 }
322 
323 Proc*
324 _threadproc(void)
325 {
326 	return myperproc()->proc;
327 }
328 
329 void
330 _threadsetproc(Proc *p)
331 {
332 	Perproc *pp;
333 
334 	if(p)
335 		p->osprocid = getpid();
336 	pp = newperproc();
337 	pp->proc = p;
338 	if(p == nil)
339 		pp->pid = -1;
340 }
341 
342 void
343 _pthreadinit(void)
344 {
345 	__isthreaded = 1;
346 	signal(SIGUSR2, sigusr2handler);
347 }
348 
349 void
350 _threadpexit(void)
351 {
352 	_exit(0);
353 }
354 
355 
356 /*
357  * FreeBSD 4 and earlier needs the context functions.
358  */
359 void
360 makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
361 {
362 	int *sp;
363 
364 	sp = (int*)ucp->uc_stack.ss_sp+ucp->uc_stack.ss_size/4;
365 	sp -= argc;
366 	memmove(sp, &argc+1, argc*sizeof(int));
367 	*--sp = 0;		/* return address */
368 	ucp->uc_mcontext.mc_eip = (long)func;
369 	ucp->uc_mcontext.mc_esp = (int)sp;
370 }
371 
372 extern int getmcontext(mcontext_t*);
373 extern int setmcontext(mcontext_t*);
374 
375 int
376 getcontext(ucontext_t *uc)
377 {
378 	return getmcontext(&uc->uc_mcontext);
379 }
380 
381 void
382 setcontext(ucontext_t *uc)
383 {
384 	setmcontext(&uc->uc_mcontext);
385 }
386 
387 int
388 swapcontext(ucontext_t *oucp, ucontext_t *ucp)
389 {
390 	if(getcontext(oucp) == 0)
391 		setcontext(ucp);
392 	return 0;
393 }
394