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libthread: handle spurious _procsleep wakeups, fix $LIBTHREAD handling

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This commit is contained in:
Russ Cox 2020-05-17 22:31:38 -04:00
parent baef953da2
commit 162d0d5cd9
2 changed files with 26 additions and 6 deletions
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4
src/libthread/pthread.c
View file

@ -50,13 +50,15 @@ _threadunlock(Lock *lk, ulong pc)
abort(); abort();
} }
/* note: _procsleep can have spurious wakeups, like pthread_cond_wait */
void void
_procsleep(_Procrendez *r) _procsleep(_Procrendez *r)
{ {
/* r is protected by r->l, which we hold */ /* r is protected by r->l, which we hold */
pthread_cond_init(&r->cond, 0); pthread_cond_init(&r->cond, 0);
r->asleep = 1; r->asleep = 1;
pthread_cond_wait(&r->cond, &r->l->mutex); if(pthread_cond_wait(&r->cond, &r->l->mutex) != 0)
sysfatal("pthread_cond_wait: %r");
pthread_cond_destroy(&r->cond); pthread_cond_destroy(&r->cond);
r->asleep = 0; r->asleep = 0;
} }

28
src/libthread/thread.c
View file

@ -54,9 +54,9 @@ _threaddebug(char *fmt, ...)
va_end(arg); va_end(arg);
t = proc()->thread; t = proc()->thread;
if(t) if(t)
fprint(fd, "%d.%d: %s\n", getpid(), t->id, buf); fprint(fd, "%p %d.%d: %s\n", proc(), getpid(), t->id, buf);
else else
fprint(fd, "%d._: %s\n", getpid(), buf); fprint(fd, "%p %d._: %s\n", proc(), getpid(), buf);
} }
static _Thread* static _Thread*
@ -219,20 +219,28 @@ proccreate(void (*fn)(void*), void *arg, uint stack)
static void static void
procswitch(Proc *p, _Thread *from, _Thread *to) procswitch(Proc *p, _Thread *from, _Thread *to)
{ {
// fprint(2, "procswitch %p %d %d\n", p, from?from->id:-1, to?to->id:-1); _threaddebug("procswitch %p %d %d", p, from?from->id:-1, to?to->id:-1);
lock(&p->schedlock); lock(&p->schedlock);
from->schedrend.l = &p->schedlock; from->schedrend.l = &p->schedlock;
if(to) { if(to) {
p->schedthread = to; p->schedthread = to;
to->schedrend.l = &p->schedlock; to->schedrend.l = &p->schedlock;
_threaddebug("procswitch wakeup %p %d", p, to->id);
_procwakeup(&to->schedrend); _procwakeup(&to->schedrend);
} }
if(p->schedthread != from) { if(p->schedthread != from) {
if(from->exiting) { if(from->exiting) {
unlock(&p->schedlock); unlock(&p->schedlock);
_threadpexit(); _threadpexit();
_threaddebug("procswitch exit wakeup!!!\n");
} }
_procsleep(&from->schedrend); while(p->schedthread != from) {
_threaddebug("procswitch sleep %p %d", p, from->id);
_procsleep(&from->schedrend);
_threaddebug("procswitch awake %p %d", p, from->id);
}
if(p->schedthread != from)
sysfatal("_procswitch %p %p oops", p->schedthread, from);
} }
unlock(&p->schedlock); unlock(&p->schedlock);
} }
@ -448,6 +456,7 @@ Top:
procswitch(p, p->thread0, t); procswitch(p, p->thread0, t);
else else
contextswitch(&p->schedcontext, &t->context); contextswitch(&p->schedcontext, &t->context);
_threaddebug("back in scheduler");
/*print("back in scheduler\n"); */ /*print("back in scheduler\n"); */
goto Top; goto Top;
} }
@ -589,6 +598,10 @@ threadqlock(QLock *l, int block, ulong pc)
if(l->owner == nil){ if(l->owner == nil){
l->owner = (*threadnow)(); l->owner = (*threadnow)();
/*print("qlock %p @%#x by %p\n", l, pc, l->owner); */ /*print("qlock %p @%#x by %p\n", l, pc, l->owner); */
if(l->owner == nil) {
fprint(2, "%s: qlock uncontended owner=nil oops\n", argv0);
abort();
}
unlock(&l->l); unlock(&l->l);
return 1; return 1;
} }
@ -613,6 +626,11 @@ threadqlock(QLock *l, int block, ulong pc)
argv0, pc, l->owner, (*threadnow)()); argv0, pc, l->owner, (*threadnow)());
abort(); abort();
} }
if(l->owner == nil) {
fprint(2, "%s: qlock threadswitch owner=nil oops\n", argv0);
abort();
}
/*print("qlock wakeup %p @%#x by %p\n", l, pc, (*threadnow)()); */ /*print("qlock wakeup %p @%#x by %p\n", l, pc, (*threadnow)()); */
return 1; return 1;
} }
@ -818,7 +836,7 @@ main(int argc, char **argv)
// Easier to just run in pthread-per-thread mode. // Easier to just run in pthread-per-thread mode.
pthreadperthread = 1; pthreadperthread = 1;
#endif #endif
if(strstr(opts, "nodaemon") || getenv("NOLIBTHREADDAEMONIZE") == nil) if(strstr(opts, "nodaemon") == nil && getenv("NOLIBTHREADDAEMONIZE") == nil)
_threadsetupdaemonize(); _threadsetupdaemonize();
threadargc = argc; threadargc = argc;