__timedwait.c raw

   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  }
  72