include/qemu/futex.h

   1 /*
   2  * Wrappers around Linux futex syscall
   3  *
   4  * Copyright Red Hat, Inc. 2017
   5  *
   6  * Author:
   7  *  Paolo Bonzini <pbonzini@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #ifndef QEMU_FUTEX_H
  15 #define QEMU_FUTEX_H
  16
  17 #include <sys/syscall.h>
  18 #include <linux/futex.h>
  19
  20 #define qemu_futex(...)              syscall(__NR_futex, __VA_ARGS__)
  21
  22 static inline void qemu_futex_wake(void *f, int n)
  23 {
  24     qemu_futex(f, FUTEX_WAKE, n, NULL, NULL, 0);
  25 }
  26
  27 static inline void qemu_futex_wait(void *f, unsigned val)
  28 {
  29     while (qemu_futex(f, FUTEX_WAIT, (int) val, NULL, NULL, 0)) {
  30         switch (errno) {
  31         case EWOULDBLOCK:
  32             return;
  33         case EINTR:
  34             break; /* get out of switch and retry */
  35         default:
  36             abort();
  37         }
  38     }
  39 }
  40
  41 #endif /* QEMU_FUTEX_H */