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| author | Rich Felker <dalias@aerifal.cx> | 2018-09-04 21:31:47 -0400 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2018-09-04 21:31:47 -0400 |
| commit | d1fa28860634af4f0efd70d533a756b51a45f83e (patch) | |
| tree | b89bbd7ff3cd84a2021adcf1916ada90c2efc27e | |
| parent | 4e4a162d9af283cf71f7310c497672e0c2b8ca3b (diff) | |
| download | musl-d1fa28860634af4f0efd70d533a756b51a45f83e.tar.gz | |
in pthread_mutex_timedlock, avoid repeatedly reading mutex type field
compiler cannot cache immutable fields of the mutex object across
external calls it can't see, much less across atomics.
| -rw-r--r-- | src/thread/pthread_mutex_timedlock.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/src/thread/pthread_mutex_timedlock.c b/src/thread/pthread_mutex_timedlock.c index 0a240e79..f91f4a61 100644 --- a/src/thread/pthread_mutex_timedlock.c +++ b/src/thread/pthread_mutex_timedlock.c @@ -6,7 +6,8 @@ int __pthread_mutex_timedlock(pthread_mutex_t *restrict m, const struct timespec && !a_cas(&m->_m_lock, 0, EBUSY)) return 0; - int r, t, priv = (m->_m_type & 128) ^ 128; + int type = m->_m_type; + int r, t, priv = (type & 128) ^ 128; r = pthread_mutex_trylock(m); if (r != EBUSY) return r; @@ -15,9 +16,9 @@ int __pthread_mutex_timedlock(pthread_mutex_t *restrict m, const struct timespec while (spins-- && m->_m_lock && !m->_m_waiters) a_spin(); while ((r=pthread_mutex_trylock(m)) == EBUSY) { - if (!(r=m->_m_lock) || ((r&0x40000000) && (m->_m_type&4))) + if (!(r=m->_m_lock) || ((r&0x40000000) && (type&4))) continue; - if ((m->_m_type&3) == PTHREAD_MUTEX_ERRORCHECK + if ((type&3) == PTHREAD_MUTEX_ERRORCHECK && (r&0x7fffffff) == __pthread_self()->tid) return EDEADLK; |