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 #include <sys/syscall.h>
  15 #include <linux/futex.h>
  16
  17 #define qemu_futex(...)              syscall(__NR_futex, __VA_ARGS__)
  18
  19 static inline void qemu_futex_wake(void *f, int n)
  20 {
  21     qemu_futex(f, FUTEX_WAKE, n, NULL, NULL, 0);
  22 }
  23
  24 static inline void qemu_futex_wait(void *f, unsigned val)
  25 {
  26     while (qemu_futex(f, FUTEX_WAIT, (int) val, NULL, NULL, 0)) {
  27         switch (errno) {
  28         case EWOULDBLOCK:
  29             return;
  30         case EINTR:
  31             break; /* get out of switch and retry */
  32         default:
  33             abort();
  34         }
  35     }
  36 }