diff options
Diffstat (limited to 'libc-top-half/musl/src/thread/pthread_mutex_trylock.c')
-rw-r--r-- | libc-top-half/musl/src/thread/pthread_mutex_trylock.c | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/libc-top-half/musl/src/thread/pthread_mutex_trylock.c b/libc-top-half/musl/src/thread/pthread_mutex_trylock.c new file mode 100644 index 0000000..c60b45f --- /dev/null +++ b/libc-top-half/musl/src/thread/pthread_mutex_trylock.c @@ -0,0 +1,78 @@ +#include "pthread_impl.h" + +int __pthread_mutex_trylock_owner(pthread_mutex_t *m) +{ + int old, own; + int type = m->_m_type; + pthread_t self = __pthread_self(); + int tid = self->tid; + + old = m->_m_lock; + own = old & 0x3fffffff; + if (own == tid) { + if ((type&8) && m->_m_count<0) { + old &= 0x40000000; + m->_m_count = 0; + goto success; + } + if ((type&3) == PTHREAD_MUTEX_RECURSIVE) { + if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN; + m->_m_count++; + return 0; + } + } + if (own == 0x3fffffff) return ENOTRECOVERABLE; + if (own || (old && !(type & 4))) return EBUSY; + + if (type & 128) { + if (!self->robust_list.off) { + self->robust_list.off = (char*)&m->_m_lock-(char *)&m->_m_next; +#ifdef __wasilibc_unmodified_upstream + __syscall(SYS_set_robust_list, &self->robust_list, 3*sizeof(long)); +#endif + } + if (m->_m_waiters) tid |= 0x80000000; + self->robust_list.pending = &m->_m_next; + } + tid |= old & 0x40000000; + + if (a_cas(&m->_m_lock, old, tid) != old) { + self->robust_list.pending = 0; + if ((type&12)==12 && m->_m_waiters) return ENOTRECOVERABLE; + return EBUSY; + } + +success: + if ((type&8) && m->_m_waiters) { + int priv = (type & 128) ^ 128; +#ifdef __wasilibc_unmodified_upstream + __syscall(SYS_futex, &m->_m_lock, FUTEX_UNLOCK_PI|priv); +#endif + self->robust_list.pending = 0; + return (type&4) ? ENOTRECOVERABLE : EBUSY; + } + + volatile void *next = self->robust_list.head; + m->_m_next = next; + m->_m_prev = &self->robust_list.head; + if (next != &self->robust_list.head) *(volatile void *volatile *) + ((char *)next - sizeof(void *)) = &m->_m_next; + self->robust_list.head = &m->_m_next; + self->robust_list.pending = 0; + + if (old) { + m->_m_count = 0; + return EOWNERDEAD; + } + + return 0; +} + +int __pthread_mutex_trylock(pthread_mutex_t *m) +{ + if ((m->_m_type&15) == PTHREAD_MUTEX_NORMAL) + return a_cas(&m->_m_lock, 0, EBUSY) & EBUSY; + return __pthread_mutex_trylock_owner(m); +} + +weak_alias(__pthread_mutex_trylock, pthread_mutex_trylock); |