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Merge "POSIX says pthread_mutex_trylock returns EBUSY, not EDEADLK."

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Elliott Hughes 2014-10-27 17:38:33 +00:00 committed by Gerrit Code Review
commit 7f164f6052
1 changed files with 12 additions and 11 deletions
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23
libc/bionic/pthread_mutex.cpp
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@ -578,15 +578,12 @@ int pthread_mutex_unlock(pthread_mutex_t* mutex) {
} }
int pthread_mutex_trylock(pthread_mutex_t* mutex) { int pthread_mutex_trylock(pthread_mutex_t* mutex) {
int mvalue, mtype, tid, shared; int mvalue = mutex->value;
int mtype = (mvalue & MUTEX_TYPE_MASK);
int shared = (mvalue & MUTEX_SHARED_MASK);
mvalue = mutex->value; // Handle common case first.
mtype = (mvalue & MUTEX_TYPE_MASK); if (__predict_true(mtype == MUTEX_TYPE_BITS_NORMAL)) {
shared = (mvalue & MUTEX_SHARED_MASK);
/* Handle common case first */
if ( __predict_true(mtype == MUTEX_TYPE_BITS_NORMAL) )
{
if (__bionic_cmpxchg(shared|MUTEX_STATE_BITS_UNLOCKED, if (__bionic_cmpxchg(shared|MUTEX_STATE_BITS_UNLOCKED,
shared|MUTEX_STATE_BITS_LOCKED_UNCONTENDED, shared|MUTEX_STATE_BITS_LOCKED_UNCONTENDED,
&mutex->value) == 0) { &mutex->value) == 0) {
@ -597,10 +594,14 @@ int pthread_mutex_trylock(pthread_mutex_t* mutex) {
return EBUSY; return EBUSY;
} }
/* Do we already own this recursive or error-check mutex ? */ // Do we already own this recursive or error-check mutex?
tid = __get_thread()->tid; pid_t tid = __get_thread()->tid;
if ( tid == MUTEX_OWNER_FROM_BITS(mvalue) ) if (tid == MUTEX_OWNER_FROM_BITS(mvalue)) {
if (mtype == MUTEX_TYPE_BITS_ERRORCHECK) {
return EBUSY;
}
return _recursive_increment(mutex, mvalue, mtype); return _recursive_increment(mutex, mvalue, mtype);
}
/* Same as pthread_mutex_lock, except that we don't want to wait, and /* Same as pthread_mutex_lock, except that we don't want to wait, and
* the only operation that can succeed is a single cmpxchg to acquire the * the only operation that can succeed is a single cmpxchg to acquire the