master
1#include "pthread_impl.h"
2
3#define IS32BIT(x) !((x)+0x80000000ULL>>32)
4#define CLAMP(x) (int)(IS32BIT(x) ? (x) : 0x7fffffffU+((0ULL+(x))>>63))
5
6static int __futex4(volatile void *addr, int op, int val, const struct timespec *to)
7{
8#ifdef SYS_futex_time64
9 time_t s = to ? to->tv_sec : 0;
10 long ns = to ? to->tv_nsec : 0;
11 int r = -ENOSYS;
12 if (SYS_futex == SYS_futex_time64 || !IS32BIT(s))
13 r = __syscall(SYS_futex_time64, addr, op, val,
14 to ? ((long long[]){s, ns}) : 0);
15 if (SYS_futex == SYS_futex_time64 || r!=-ENOSYS) return r;
16 to = to ? (void *)(long[]){CLAMP(s), ns} : 0;
17#endif
18 return __syscall(SYS_futex, addr, op, val, to);
19}
20
21static int pthread_mutex_timedlock_pi(pthread_mutex_t *restrict m, const struct timespec *restrict at)
22{
23 int type = m->_m_type;
24 int priv = (type & 128) ^ 128;
25 pthread_t self = __pthread_self();
26 int e;
27
28 if (!priv) self->robust_list.pending = &m->_m_next;
29
30 do e = -__futex4(&m->_m_lock, FUTEX_LOCK_PI|priv, 0, at);
31 while (e==EINTR);
32 if (e) self->robust_list.pending = 0;
33
34 switch (e) {
35 case 0:
36 /* Catch spurious success for non-robust mutexes. */
37 if (!(type&4) && ((m->_m_lock & 0x40000000) || m->_m_waiters)) {
38 a_store(&m->_m_waiters, -1);
39 __syscall(SYS_futex, &m->_m_lock, FUTEX_UNLOCK_PI|priv);
40 self->robust_list.pending = 0;
41 break;
42 }
43 /* Signal to trylock that we already have the lock. */
44 m->_m_count = -1;
45 return __pthread_mutex_trylock(m);
46 case ETIMEDOUT:
47 return e;
48 case EDEADLK:
49 if ((type&3) == PTHREAD_MUTEX_ERRORCHECK) return e;
50 }
51 do e = __timedwait(&(int){0}, 0, CLOCK_REALTIME, at, 1);
52 while (e != ETIMEDOUT);
53 return e;
54}
55
56int __pthread_mutex_timedlock(pthread_mutex_t *restrict m, const struct timespec *restrict at)
57{
58 if ((m->_m_type&15) == PTHREAD_MUTEX_NORMAL
59 && !a_cas(&m->_m_lock, 0, EBUSY))
60 return 0;
61
62 int type = m->_m_type;
63 int r, t, priv = (type & 128) ^ 128;
64
65 r = __pthread_mutex_trylock(m);
66 if (r != EBUSY) return r;
67
68 if (type&8) return pthread_mutex_timedlock_pi(m, at);
69
70 int spins = 100;
71 while (spins-- && m->_m_lock && !m->_m_waiters) a_spin();
72
73 while ((r=__pthread_mutex_trylock(m)) == EBUSY) {
74 r = m->_m_lock;
75 int own = r & 0x3fffffff;
76 if (!own && (!r || (type&4)))
77 continue;
78 if ((type&3) == PTHREAD_MUTEX_ERRORCHECK
79 && own == __pthread_self()->tid)
80 return EDEADLK;
81
82 a_inc(&m->_m_waiters);
83 t = r | 0x80000000;
84 a_cas(&m->_m_lock, r, t);
85 r = __timedwait(&m->_m_lock, t, CLOCK_REALTIME, at, priv);
86 a_dec(&m->_m_waiters);
87 if (r && r != EINTR) break;
88 }
89 return r;
90}
91
92weak_alias(__pthread_mutex_timedlock, pthread_mutex_timedlock);