src/thread/__timedwait.c

   1 #include <pthread.h>
   2 #include <time.h>
   3 #include <errno.h>
   4 #include "futex.h"
   5 #include "syscall.h"
   6 #include "pthread_impl.h"
   7
   8 #define IS32BIT(x) !((x)+0x80000000ULL>>32)
   9 #define CLAMP(x) (int)(IS32BIT(x) ? (x) : 0x7fffffffU+((0ULL+(x))>>63))
  10
  11 static int __futex4_cp(volatile void *addr, int op, int val, const struct timespec *to)
  12 {
  13         int r;
  14 #ifdef SYS_futex_time64
  15         time_t s = to ? to->tv_sec : 0;
  16         long ns = to ? to->tv_nsec : 0;
  17         r = -ENOSYS;
  18         if (SYS_futex == SYS_futex_time64 || !IS32BIT(s))
  19                 r = __syscall_cp(SYS_futex_time64, addr, op, val,
  20                         to ? ((long long[]){s, ns}) : 0);
  21         if (SYS_futex == SYS_futex_time64 || r!=-ENOSYS) return r;
  22         to = to ? (void *)(long[]){CLAMP(s), ns} : 0;
  23 #endif
  24         r = __syscall_cp(SYS_futex, addr, op, val, to);
  25         if (r != -ENOSYS) return r;
  26         return __syscall_cp(SYS_futex, addr, op & ~FUTEX_PRIVATE, val, to);
  27 }
  28
  29 static volatile int dummy = 0;
  30 weak_alias(dummy, __eintr_valid_flag);
  31
  32 int __timedwait_cp(volatile int *addr, int val,
  33         clockid_t clk, const struct timespec *at, int priv)
  34 {
  35         int r;
  36         struct timespec to, *top=0;
  37
  38         if (priv) priv = FUTEX_PRIVATE;
  39
  40         if (at) {
  41                 if (at->tv_nsec >= 1000000000UL) return EINVAL;
  42                 if (__clock_gettime(clk, &to)) return EINVAL;
  43                 to.tv_sec = at->tv_sec - to.tv_sec;
  44                 if ((to.tv_nsec = at->tv_nsec - to.tv_nsec) < 0) {
  45                         to.tv_sec--;
  46                         to.tv_nsec += 1000000000;
  47                 }
  48                 if (to.tv_sec < 0) return ETIMEDOUT;
  49                 top = &to;
  50         }
  51
  52         r = -__futex4_cp(addr, FUTEX_WAIT|priv, val, top);
  53         if (r != EINTR && r != ETIMEDOUT && r != ECANCELED) r = 0;
  54         /* Mitigate bug in old kernels wrongly reporting EINTR for non-
  55          * interrupting (SA_RESTART) signal handlers. This is only practical
  56          * when NO interrupting signal handlers have been installed, and
  57          * works by sigaction tracking whether that's the case. */
  58         if (r == EINTR && !__eintr_valid_flag) r = 0;
  59
  60         return r;
  61 }
  62
  63 int __timedwait(volatile int *addr, int val,
  64         clockid_t clk, const struct timespec *at, int priv)
  65 {
  66         int cs, r;
  67         __pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
  68         r = __timedwait_cp(addr, val, clk, at, priv);
  69         __pthread_setcancelstate(cs, 0);
  70         return r;
  71 }