recovering ownerdead robust mutex must reset recursive lock count

[musl] / src / thread / pthread_mutex_trylock.c

diff --git a/src/thread/pthread_mutex_trylock.c b/src/thread/pthread_mutex_trylock.c
index 29268fd..db784a7 100644 (file)
--- a/src/thread/pthread_mutex_trylock.c
+++ b/src/thread/pthread_mutex_trylock.c
@@ -2,27 +2,51 @@
 
 int pthread_mutex_trylock(pthread_mutex_t *m)
 {
-       if (m->_m_type == PTHREAD_MUTEX_RECURSIVE) {
-               pthread_t self = pthread_self();
-               if (m->_m_owner == self->tid) {
-                       if ((unsigned)m->_m_lock >= INT_MAX) return EAGAIN;
-                       a_inc(&m->_m_lock);
-                       return 0;
-               }
-               if (a_fetch_add(&m->_m_lock, 1)) {
-                       if (a_fetch_add(&m->_m_lock, -1)==1 && m->_m_waiters)
-                               __wake(&m->_m_lock, 1, 0);
-                       return EBUSY;
-               }
-               m->_m_owner = self->tid;
+       int tid, old, own;
+       pthread_t self;
+
+       if (m->_m_type == PTHREAD_MUTEX_NORMAL)
+               return a_cas(&m->_m_lock, 0, EBUSY) & EBUSY;
+
+       self = pthread_self();
+       tid = self->tid;
+
+       if (m->_m_type >= 4) {
+               if (!self->robust_list.off)
+                       __syscall(SYS_set_robust_list,
+                               &self->robust_list, 3*sizeof(long));
+               self->robust_list.off = (char*)&m->_m_lock-(char *)&m->_m_next;
+               self->robust_list.pending = &m->_m_next;
+       }
+
+       old = m->_m_lock;
+       own = old & 0x7fffffff;
+       if (own == tid && (m->_m_type&3) == PTHREAD_MUTEX_RECURSIVE) {
+               if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN;
+               m->_m_count++;
                return 0;
        }
 
-       if (a_xchg(&m->_m_lock, 1))
-               if (m->_m_type == PTHREAD_MUTEX_ERRORCHECK
-                && m->_m_owner == pthread_self()->tid) return EDEADLK;
-               else return EBUSY;
-       if (m->_m_type == PTHREAD_MUTEX_ERRORCHECK)
-               m->_m_owner = pthread_self()->tid;
+       if ((own && !(own & 0x40000000)) || a_cas(&m->_m_lock, old, tid)!=old)
+               return EBUSY;
+
+       if (m->_m_type < 4) return 0;
+
+       if (m->_m_type >= 8) {
+               m->_m_lock = 0;
+               return ENOTRECOVERABLE;
+       }
+       m->_m_next = self->robust_list.head;
+       m->_m_prev = &self->robust_list.head;
+       if (self->robust_list.head)
+               self->robust_list.head[-1] = &m->_m_next;
+       self->robust_list.head = &m->_m_next;
+       self->robust_list.pending = 0;
+       if (own) {
+               m->_m_count = 0;
+               m->_m_type += 8;
+               return EOWNERDEAD;
+       }
+
        return 0;
 }