93 lines
2.5 KiB
C
93 lines
2.5 KiB
C
#include "pthread_impl.h"
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#define IS32BIT(x) !((x)+0x80000000ULL>>32)
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#define CLAMP(x) (int)(IS32BIT(x) ? (x) : 0x7fffffffU+((0ULL+(x))>>63))
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static int __futex4(volatile void *addr, int op, int val, const struct timespec *to)
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{
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#ifdef SYS_futex_time64
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time_t s = to ? to->tv_sec : 0;
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long ns = to ? to->tv_nsec : 0;
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int r = -ENOSYS;
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if (SYS_futex == SYS_futex_time64 || !IS32BIT(s))
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r = __syscall(SYS_futex_time64, addr, op, val,
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to ? ((long long[]){s, ns}) : 0);
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if (SYS_futex == SYS_futex_time64 || r!=-ENOSYS) return r;
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to = to ? (void *)(long[]){CLAMP(s), ns} : 0;
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#endif
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return __syscall(SYS_futex, addr, op, val, to);
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}
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static int pthread_mutex_timedlock_pi(pthread_mutex_t *restrict m, const struct timespec *restrict at)
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{
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int type = m->_m_type;
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int priv = (type & 128) ^ 128;
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pthread_t self = __pthread_self();
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int e;
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if (!priv) self->robust_list.pending = &m->_m_next;
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do e = -__futex4(&m->_m_lock, FUTEX_LOCK_PI|priv, 0, at);
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while (e==EINTR);
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if (e) self->robust_list.pending = 0;
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switch (e) {
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case 0:
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/* Catch spurious success for non-robust mutexes. */
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if (!(type&4) && ((m->_m_lock & 0x40000000) || m->_m_waiters)) {
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a_store(&m->_m_waiters, -1);
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__syscall(SYS_futex, &m->_m_lock, FUTEX_UNLOCK_PI|priv);
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self->robust_list.pending = 0;
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break;
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}
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/* Signal to trylock that we already have the lock. */
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m->_m_count = -1;
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return __pthread_mutex_trylock(m);
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case ETIMEDOUT:
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return e;
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case EDEADLK:
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if ((type&3) == PTHREAD_MUTEX_ERRORCHECK) return e;
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}
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do e = __timedwait(&(int){0}, 0, CLOCK_REALTIME, at, 1);
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while (e != ETIMEDOUT);
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return e;
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}
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int __pthread_mutex_timedlock(pthread_mutex_t *restrict m, const struct timespec *restrict at)
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{
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if ((m->_m_type&15) == PTHREAD_MUTEX_NORMAL
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&& !a_cas(&m->_m_lock, 0, EBUSY))
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return 0;
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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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if (type&8) return pthread_mutex_timedlock_pi(m, at);
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int spins = 100;
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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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r = m->_m_lock;
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int own = r & 0x3fffffff;
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if (!own && (!r || (type&4)))
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continue;
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if ((type&3) == PTHREAD_MUTEX_ERRORCHECK
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&& own == __pthread_self()->tid)
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return EDEADLK;
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a_inc(&m->_m_waiters);
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t = r | 0x80000000;
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a_cas(&m->_m_lock, r, t);
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r = __timedwait(&m->_m_lock, t, CLOCK_REALTIME, at, priv);
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a_dec(&m->_m_waiters);
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if (r && r != EINTR) break;
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}
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return r;
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}
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weak_alias(__pthread_mutex_timedlock, pthread_mutex_timedlock);
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