_lwp_wakeup —
make a blocked light-weight process runnable
Standard C Library (libc, -lc)
#include <lwp.h>
int
  
  _lwp_wakeup(lwpid_t
    lwp);
_lwp_wakeup() makes a blocked LWP runnable. The blocked
  LWP must be in LSSLEEP state. Unblocking the LWP does
  not guarantee that it will make progress; it may block again as soon as it
  resumes execution in the kernel.
_lwp_wakeup() will fail if:
  - [ESRCH]
- No LWP can be found in the current process corresponding to that specified
      by lwp.
- [ENODEV]
- The specified LWP is not in LSSLEEPstate.
- [EBUSY]
- The specified LWP is blocked in an uninterruptible sleep.
The_lwp_wakeup() system call first appeared in
  NetBSD 2.0.