42 lines
1.5 KiB
Diff
42 lines
1.5 KiB
Diff
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From d1fa28860634af4f0efd70d533a756b51a45f83e Mon Sep 17 00:00:00 2001
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From: Rich Felker <dalias@aerifal.cx>
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Date: Tue, 4 Sep 2018 21:31:47 -0400
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Subject: [PATCH 2/3] in pthread_mutex_timedlock, avoid repeatedly reading
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mutex type field
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compiler cannot cache immutable fields of the mutex object across
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external calls it can't see, much less across atomics.
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---
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src/thread/pthread_mutex_timedlock.c | 7 ++++---
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1 file changed, 4 insertions(+), 3 deletions(-)
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diff --git a/src/thread/pthread_mutex_timedlock.c b/src/thread/pthread_mutex_timedlock.c
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index 0a240e79..f91f4a61 100644
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--- a/src/thread/pthread_mutex_timedlock.c
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+++ b/src/thread/pthread_mutex_timedlock.c
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@@ -6,7 +6,8 @@ int __pthread_mutex_timedlock(pthread_mutex_t *restrict m, const struct timespec
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&& !a_cas(&m->_m_lock, 0, EBUSY))
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return 0;
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- int r, t, priv = (m->_m_type & 128) ^ 128;
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+ int type = m->_m_type;
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+ int r, t, priv = (type & 128) ^ 128;
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r = pthread_mutex_trylock(m);
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if (r != EBUSY) return r;
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@@ -15,9 +16,9 @@ int __pthread_mutex_timedlock(pthread_mutex_t *restrict m, const struct timespec
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while (spins-- && m->_m_lock && !m->_m_waiters) a_spin();
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while ((r=pthread_mutex_trylock(m)) == EBUSY) {
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- if (!(r=m->_m_lock) || ((r&0x40000000) && (m->_m_type&4)))
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+ if (!(r=m->_m_lock) || ((r&0x40000000) && (type&4)))
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continue;
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- if ((m->_m_type&3) == PTHREAD_MUTEX_ERRORCHECK
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+ if ((type&3) == PTHREAD_MUTEX_ERRORCHECK
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&& (r&0x7fffffff) == __pthread_self()->tid)
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return EDEADLK;
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--
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2.19.0
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