int
pthread_cond_destroy(pthread_cond_t *ocond)
{
_pthread_cond *cond = (_pthread_cond *)ocond;
int res = EINVAL;
if (cond->sig == _PTHREAD_COND_SIG) {
LOCK(cond->lock);
uint64_t oldval64, newval64;
uint32_t lcntval, ucntval, scntval;
volatile uint32_t *c_lseqcnt, *c_useqcnt, *c_sseqcnt;
COND_GETSEQ_ADDR(cond, &c_lseqcnt, &c_useqcnt, &c_sseqcnt);
do {
lcntval = *c_lseqcnt;
ucntval = *c_useqcnt;
scntval = *c_sseqcnt;
// validate it is not busy
if ((lcntval & PTHRW_COUNT_MASK) != (scntval & PTHRW_COUNT_MASK)) {
//res = EBUSY;
break;
}
oldval64 = (((uint64_t)scntval) << 32);
oldval64 |= lcntval;
newval64 = oldval64;
} while (OSAtomicCompareAndSwap64Barrier(oldval64, newval64, (volatile int64_t *)c_lseqcnt) != TRUE);
// <rdar://problem/13782056> Need to clear preposts.
uint32_t flags = 0;
bool needclearpre = ((scntval & PTH_RWS_CV_PBIT) != 0);
if (needclearpre && cond->pshared == PTHREAD_PROCESS_SHARED) {
flags |= _PTHREAD_MTX_OPT_PSHARED;
}
cond->sig = _PTHREAD_NO_SIG;
res = 0;
UNLOCK(cond->lock);
if (needclearpre) {
(void)__psynch_cvclrprepost(cond, lcntval, ucntval, scntval, 0, lcntval, flags);
}
} else if (cond->sig == _PTHREAD_COND_SIG_init) {
// Compatibility for misbehaving applications that attempt to
// destroy a statically initialized condition variable.
cond->sig = _PTHREAD_NO_SIG;
res = 0;
}
return res;
}
static void
_pthread_cond_updateval(_pthread_cond *cond, int error, uint32_t updateval)
{
int needclearpre;
uint32_t diffgen, nsval;
uint64_t oldval64, newval64;
uint32_t lcntval, ucntval, scntval;
volatile uint32_t *c_lseqcnt, *c_useqcnt, *c_sseqcnt;
if (error != 0) {
updateval = PTHRW_INC;
if ((error & ECVCERORR) != 0) {
updateval |= PTH_RWS_CV_CBIT;
}
if ((error & ECVPERORR) != 0) {
updateval |= PTH_RWS_CV_PBIT;
}
}
COND_GETSEQ_ADDR(cond, &c_lseqcnt, &c_useqcnt, &c_sseqcnt);
do {
lcntval = *c_lseqcnt;
ucntval = *c_useqcnt;
scntval = *c_sseqcnt;
diffgen = diff_genseq(lcntval, scntval); // pending waiters
oldval64 = (((uint64_t)scntval) << 32);
oldval64 |= lcntval;
if (diffgen <= 0) {
/* TBD: Assert, should not be the case */
/* validate it is spurious and return */
newval64 = oldval64;
} else {
// update S by one
// update scntval with number of expected returns and bits
nsval = (scntval & PTHRW_COUNT_MASK) + (updateval & PTHRW_COUNT_MASK);
// set bits
nsval |= ((scntval & PTH_RWS_CV_BITSALL) | (updateval & PTH_RWS_CV_BITSALL));
// if L==S and c&p bits are set, needs clearpre
if (((nsval & PTHRW_COUNT_MASK) == (lcntval & PTHRW_COUNT_MASK)) &&
((nsval & PTH_RWS_CV_BITSALL) == PTH_RWS_CV_BITSALL)) {
// reset p bit but retain c bit on the sword
nsval &= PTH_RWS_CV_RESET_PBIT;
needclearpre = 1;
} else {
needclearpre = 0;
}
newval64 = (((uint64_t)nsval) << 32);
newval64 |= lcntval;
}
} while (OSAtomicCompareAndSwap64Barrier(oldval64, newval64, (volatile int64_t *)c_lseqcnt) != TRUE);
if (diffgen > 0) {
// if L == S, then reset associated mutex
if ((nsval & PTHRW_COUNT_MASK) == (lcntval & PTHRW_COUNT_MASK)) {
cond->busy = NULL;
}
if (needclearpre != 0) {
uint32_t flags = 0;
if (cond->pshared == PTHREAD_PROCESS_SHARED) {
flags |= _PTHREAD_MTX_OPT_PSHARED;
}
(void)__psynch_cvclrprepost(cond, lcntval, ucntval, nsval, 0, lcntval, flags);
}
}
}
/*
* Suspend waiting for a condition variable.
* Note: we have to keep a list of condition variables which are using
* this same mutex variable so we can detect invalid 'destroy' sequences.
* If isconforming < 0, we skip the _pthread_testcancel(), but keep the
* remaining conforming behavior..
*/
__private_extern__ int
_pthread_cond_wait(pthread_cond_t *ocond,
pthread_mutex_t *omutex,
const struct timespec *abstime,
int isRelative,
int isconforming)
{
int res;
_pthread_cond *cond = (_pthread_cond *)ocond;
_pthread_mutex *mutex = (_pthread_mutex *)omutex;
struct timespec then = { 0, 0 };
uint32_t mtxgen, mtxugen, flags=0, updateval;
uint32_t lcntval, ucntval, scntval;
uint32_t nlval, ulval, savebits;
volatile uint32_t *c_lseqcnt, *c_useqcnt, *c_sseqcnt;
uint64_t oldval64, newval64, mugen, cvlsgen;
uint32_t *npmtx = NULL;
extern void _pthread_testcancel(pthread_t thread, int isconforming);
res = _pthread_cond_check_init(cond, NULL);
if (res != 0) {
return res;
}
if (isconforming) {
if (mutex->sig != _PTHREAD_MUTEX_SIG && (mutex->sig & _PTHREAD_MUTEX_SIG_init_MASK) != _PTHREAD_MUTEX_SIG_CMP) {
return EINVAL;
}
if (isconforming > 0) {
_pthread_testcancel(pthread_self(), 1);
}
}
/* send relative time to kernel */
if (abstime) {
if (isRelative == 0) {
struct timespec now;
struct timeval tv;
__gettimeofday(&tv, NULL);
TIMEVAL_TO_TIMESPEC(&tv, &now);
/* Compute relative time to sleep */
then.tv_nsec = abstime->tv_nsec - now.tv_nsec;
then.tv_sec = abstime->tv_sec - now.tv_sec;
if (then.tv_nsec < 0) {
then.tv_nsec += NSEC_PER_SEC;
then.tv_sec--;
}
if (then.tv_sec < 0 || (then.tv_sec == 0 && then.tv_nsec == 0)) {
return ETIMEDOUT;
}
if (isconforming &&
(abstime->tv_sec < 0 ||
abstime->tv_nsec < 0 ||
abstime->tv_nsec >= NSEC_PER_SEC)) {
return EINVAL;
}
} else {
then.tv_sec = abstime->tv_sec;
then.tv_nsec = abstime->tv_nsec;
if ((then.tv_sec == 0) && (then.tv_nsec == 0)) {
return ETIMEDOUT;
}
}
if (isconforming && (then.tv_sec < 0 || then.tv_nsec < 0)) {
return EINVAL;
}
if (then.tv_nsec >= NSEC_PER_SEC) {
return EINVAL;
}
}
if (cond->busy != NULL && cond->busy != mutex) {
return EINVAL;
}
COND_GETSEQ_ADDR(cond, &c_lseqcnt, &c_useqcnt, &c_sseqcnt);
do {
lcntval = *c_lseqcnt;
ucntval = *c_useqcnt;
scntval = *c_sseqcnt;
oldval64 = (((uint64_t)scntval) << 32);
oldval64 |= lcntval;
/* remove c and p bits on S word */
savebits = scntval & PTH_RWS_CV_BITSALL;
ulval = (scntval & PTHRW_COUNT_MASK);
nlval = lcntval + PTHRW_INC;
newval64 = (((uint64_t)ulval) << 32);
newval64 |= nlval;
} while (OSAtomicCompareAndSwap64Barrier(oldval64, newval64, (volatile int64_t *)c_lseqcnt) != TRUE);
cond->busy = mutex;
res = __mtx_droplock(mutex, &flags, &npmtx, &mtxgen, &mtxugen);
/* TBD: cases are for normal (non owner for recursive mutex; error checking)*/
if (res != 0) {
return EINVAL;
}
if ((flags & _PTHREAD_MTX_OPT_NOTIFY) == 0) {
npmtx = NULL;
mugen = 0;
} else {
mugen = ((uint64_t)mtxugen << 32) | mtxgen;
}
flags &= ~_PTHREAD_MTX_OPT_MUTEX; /* reset the mutex bit as this is cvar */
cvlsgen = ((uint64_t)(ulval | savebits)<< 32) | nlval;
// SUSv3 requires pthread_cond_wait to be a cancellation point
if (isconforming) {
pthread_cleanup_push(_pthread_cond_cleanup, (void *)cond);
updateval = __psynch_cvwait(ocond, cvlsgen, ucntval, (pthread_mutex_t *)npmtx, mugen, flags, (int64_t)then.tv_sec, (int32_t)then.tv_nsec);
_pthread_testcancel(pthread_self(), isconforming);
pthread_cleanup_pop(0);
} else {
updateval = __psynch_cvwait(ocond, cvlsgen, ucntval, (pthread_mutex_t *)npmtx, mugen, flags, (int64_t)then.tv_sec, (int32_t)then.tv_nsec);
}
if (updateval == (uint32_t)-1) {
int err = errno;
switch (err & 0xff) {
case ETIMEDOUT:
res = ETIMEDOUT;
break;
case EINTR:
// spurious wakeup (unless canceled)
res = 0;
break;
default:
res = EINVAL;
break;
}
// add unlock ref to show one less waiter
_pthread_cond_updateval(cond, err, 0);
} else if (updateval != 0) {
// Successful wait
// The return due to prepost and might have bit states
// update S and return for prepo if needed
_pthread_cond_updateval(cond, 0, updateval);
}
pthread_mutex_lock(omutex);
return res;
}
static int
_pthread_cond_signal(pthread_cond_t *ocond, bool broadcast, mach_port_t thread)
{
int res;
_pthread_cond *cond = (_pthread_cond *)ocond;
uint32_t updateval;
uint32_t diffgen;
uint32_t ulval;
uint64_t oldval64, newval64;
uint32_t lcntval, ucntval, scntval;
volatile uint32_t *c_lseqcnt, *c_useqcnt, *c_sseqcnt;
int retry_count = 0, uretry_count = 0;
int ucountreset = 0;
bool inited = false;
res = _pthread_cond_check_init(cond, &inited);
if (res != 0 || inited == true) {
return res;
}
COND_GETSEQ_ADDR(cond, &c_lseqcnt, &c_useqcnt, &c_sseqcnt);
bool retry;
do {
retry = false;
lcntval = *c_lseqcnt;
ucntval = *c_useqcnt;
scntval = *c_sseqcnt;
if (((lcntval & PTHRW_COUNT_MASK) == (scntval & PTHRW_COUNT_MASK)) ||
(thread == MACH_PORT_NULL && ((lcntval & PTHRW_COUNT_MASK) == (ucntval & PTHRW_COUNT_MASK)))) {
/* validate it is spurious and return */
oldval64 = (((uint64_t)scntval) << 32);
oldval64 |= lcntval;
newval64 = oldval64;
if (OSAtomicCompareAndSwap64Barrier(oldval64, newval64, (volatile int64_t *)c_lseqcnt) != TRUE) {
retry = true;
continue;
} else {
return 0;
}
}
if (thread) {
break;
}
/* validate to eliminate spurious values, race snapshots */
if (is_seqhigher((scntval & PTHRW_COUNT_MASK), (lcntval & PTHRW_COUNT_MASK))) {
/* since ucntval may be newer, just redo */
retry_count++;
if (retry_count > 8192) {
return EAGAIN;
} else {
sched_yield();
retry = true;
continue;
}
} else if (is_seqhigher((ucntval & PTHRW_COUNT_MASK), (lcntval & PTHRW_COUNT_MASK))) {
/* since ucntval may be newer, just redo */
uretry_count++;
if (uretry_count > 8192) {
/*
* U value if not used for a while can go out of sync
* set this to S value and try one more time.
*/
if (ucountreset != 0) {
return EAGAIN;
} else if (OSAtomicCompareAndSwap32Barrier(ucntval, (scntval & PTHRW_COUNT_MASK), (volatile int32_t *)c_useqcnt) == TRUE) {
/* now the U is reset to S value */
ucountreset = 1;
uretry_count = 0;
}
}
sched_yield();
retry = true;
continue;
}
if (is_seqlower(ucntval & PTHRW_COUNT_MASK, scntval & PTHRW_COUNT_MASK) != 0) {
/* If U < S, set U = S+diff due to intr's TO, etc */
ulval = (scntval & PTHRW_COUNT_MASK);
} else {
/* If U >= S, set U = U+diff due to intr's TO, etc */
ulval = (ucntval & PTHRW_COUNT_MASK);
}
if (broadcast) {
diffgen = diff_genseq(lcntval, ulval);
// Set U = L
ulval = (lcntval & PTHRW_COUNT_MASK);
} else {
ulval += PTHRW_INC;
}
} while (retry || OSAtomicCompareAndSwap32Barrier(ucntval, ulval, (volatile int32_t *)c_useqcnt) != TRUE);
uint32_t flags = 0;
if (cond->pshared == PTHREAD_PROCESS_SHARED) {
flags |= _PTHREAD_MTX_OPT_PSHARED;
}
uint64_t cvlsgen = ((uint64_t)scntval << 32) | lcntval;
if (broadcast) {
// pass old U val so kernel will know the diffgen
uint64_t cvudgen = ((uint64_t)ucntval << 32) | diffgen;
updateval = __psynch_cvbroad(ocond, cvlsgen, cvudgen, flags, NULL, 0, 0);
} else {
updateval = __psynch_cvsignal(ocond, cvlsgen, ucntval, thread, NULL, 0, 0, flags);
}
if (updateval != (uint32_t)-1 && updateval != 0) {
_pthread_cond_updateval(cond, 0, updateval);
}
return 0;
}
bool cpu_CAS64(volatile i64* location, i64 expected, i64 newValue)
{
return OSAtomicCompareAndSwap64Barrier(expected, newValue, location);
}