#include <u.h>#include <libc.h> #ifdef PTHREAD static pthread_mutex_t initmutex = PTHREAD_MUTEX_INITIALIZER; static voidlockinit(Lock *lk){	pthread_mutexattr_t attr; 	pthread_mutex_lock(&initmutex);	if(lk->init == 0){		pthread_mutexattr_init(&attr);		pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_NORMAL);		pthread_mutex_init(&lk->mutex, &attr);		pthread_mutexattr_destroy(&attr);		lk->init = 1;	}	pthread_mutex_unlock(&initmutex);} voidlock(Lock *lk){	if(!lk->init)		lockinit(lk);	if(pthread_mutex_lock(&lk->mutex) != 0)		abort();} intcanlock(Lock *lk){	int r; 	if(!lk->init)		lockinit(lk);	r = pthread_mutex_trylock(&lk->mutex);	if(r == 0)		return 1;	if(r == EBUSY)		return 0;	abort();} voidunlock(Lock *lk){	if(pthread_mutex_unlock(&lk->mutex) != 0)		abort();} #else  /* old, non-pthread systems */ intcanlock(Lock *lk){	return !tas(&lk->key);} voidlock(Lock *lk){	int i; 	/* easy case */	if(canlock(lk))		return; 	/* for multi processor machines */	for(i=0; i<100; i++)		if(canlock(lk))			return; 	for(i=0; i<100; i++) {		osyield();		if(canlock(lk))			return;	} 	/* looking bad - make sure it is not a priority problem */	for(i=0; i<12; i++) {		osmsleep(1<<i);		if(canlock(lk))			return;	} 	/* we are in trouble */	for(;;) {		if(canlock(lk))			return;		iprint("lock loop %ld: val=%d &lock=%ux pc=%p\n", getpid(), lk->key, lk, getcallerpc(&lk));		osmsleep(1000);	}} voidunlock(Lock *lk){	assert(lk->key);	lk->key = 0;} #endif voidilock(Lock *lk){	lock(lk);} voidiunlock(Lock *lk){	unlock(lk);}