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| author | Rich Felker <dalias@aerifal.cx> | 2011-03-30 09:06:00 -0400 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2011-03-30 09:06:00 -0400 |
| commit | 02084109f0f0d6e0a7fe4a8cb3a90a422725e264 (patch) | |
| tree | d0c40b22c52dc87c62de4848f77d1bf48bf343fb | |
| parent | 124b4ebc8a293e616cc0a7eaba3587c9b7ff13ec (diff) | |
| download | musl-02084109f0f0d6e0a7fe4a8cb3a90a422725e264.tar.gz musl-02084109f0f0d6e0a7fe4a8cb3a90a422725e264.tar.xz musl-02084109f0f0d6e0a7fe4a8cb3a90a422725e264.zip | |
streamline mutex unlock to remove a useless branch, use a_store to unlock
this roughly halves the cost of pthread_mutex_unlock, at least for non-robust, normal-type mutexes. the a_store change is in preparation for future support of archs which require a memory barrier or special atomic store operation, and also should prevent the possibility of the compiler misordering writes.
| -rw-r--r-- | src/thread/pthread_mutex_unlock.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/src/thread/pthread_mutex_unlock.c b/src/thread/pthread_mutex_unlock.c index 67aa7ba5..5855db0b 100644 --- a/src/thread/pthread_mutex_unlock.c +++ b/src/thread/pthread_mutex_unlock.c @@ -14,11 +14,15 @@ int pthread_mutex_unlock(pthread_mutex_t *m) self->robust_list.pending = &m->_m_next; *(void **)m->_m_prev = m->_m_next; if (m->_m_next) ((void **)m->_m_next)[-1] = m->_m_prev; + a_store(&m->_m_lock, 0); + self->robust_list.pending = 0; + } else { + a_store(&m->_m_lock, 0); } + } else { + a_store(&m->_m_lock, 0); } - m->_m_lock = 0; if (m->_m_waiters) __wake(&m->_m_lock, 1, 0); - if (m->_m_type >= 4) self->robust_list.pending = 0; return 0; } |