From b1c43161c2b37e35eae60fa61621a24a5d820d83 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Thu, 17 Mar 2011 12:21:32 -0400 Subject: unify lock and owner fields of mutex structure this change is necessary to free up one slot in the mutex structure so that we can use doubly-linked lists in the implementation of robust mutexes. --- src/internal/pthread_impl.h | 1 - src/thread/pthread_mutex_lock.c | 5 +++-- src/thread/pthread_mutex_trylock.c | 5 ++--- src/thread/pthread_mutex_unlock.c | 3 +-- 4 files changed, 6 insertions(+), 8 deletions(-) diff --git a/src/internal/pthread_impl.h b/src/internal/pthread_impl.h index c1740111..102413f5 100644 --- a/src/internal/pthread_impl.h +++ b/src/internal/pthread_impl.h @@ -47,7 +47,6 @@ struct pthread { #define _m_type __u.__i[0] #define _m_lock __u.__i[1] #define _m_waiters __u.__i[2] -#define _m_owner __u.__i[3] #define _m_count __u.__i[4] #define _c_block __u.__i[0] #define _c_clock __u.__i[1] diff --git a/src/thread/pthread_mutex_lock.c b/src/thread/pthread_mutex_lock.c index 82556141..56111ec8 100644 --- a/src/thread/pthread_mutex_lock.c +++ b/src/thread/pthread_mutex_lock.c @@ -4,10 +4,11 @@ int pthread_mutex_lock(pthread_mutex_t *m) { int r; while ((r=pthread_mutex_trylock(m)) == EBUSY) { + if (!(r=m->_m_lock)) continue; if (m->_m_type == PTHREAD_MUTEX_ERRORCHECK - && m->_m_owner == pthread_self()->tid) + && r == pthread_self()->tid) return EDEADLK; - __wait(&m->_m_lock, &m->_m_waiters, 1, 0); + __wait(&m->_m_lock, &m->_m_waiters, r, 0); } return r; } diff --git a/src/thread/pthread_mutex_trylock.c b/src/thread/pthread_mutex_trylock.c index 6fc604fe..de57ff9e 100644 --- a/src/thread/pthread_mutex_trylock.c +++ b/src/thread/pthread_mutex_trylock.c @@ -9,14 +9,13 @@ int pthread_mutex_trylock(pthread_mutex_t *m) tid = pthread_self()->tid; - if (m->_m_owner == tid && m->_m_type == PTHREAD_MUTEX_RECURSIVE) { + if (m->_m_lock == tid && m->_m_type == PTHREAD_MUTEX_RECURSIVE) { if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN; m->_m_count++; return 0; } - if (m->_m_owner || a_xchg(&m->_m_lock, 1)) return EBUSY; - m->_m_owner = tid; + if (m->_m_lock || a_cas(&m->_m_lock, 0, tid)) return EBUSY; m->_m_count = 1; return 0; } diff --git a/src/thread/pthread_mutex_unlock.c b/src/thread/pthread_mutex_unlock.c index 39cea4b6..61a2b947 100644 --- a/src/thread/pthread_mutex_unlock.c +++ b/src/thread/pthread_mutex_unlock.c @@ -3,13 +3,12 @@ int pthread_mutex_unlock(pthread_mutex_t *m) { if (m->_m_type != PTHREAD_MUTEX_NORMAL) { - if (m->_m_owner != pthread_self()->tid) + if (m->_m_lock != pthread_self()->tid) return EPERM; if (m->_m_type == PTHREAD_MUTEX_RECURSIVE && --m->_m_count) return 0; } - m->_m_owner = 0; m->_m_lock = 0; if (m->_m_waiters) __wake(&m->_m_lock, 1, 0); return 0; -- cgit v1.2.1