zx_vmar_unmap_handle_close_thread_exit

Summary

Unmap memory, close handle, exit.

Declaration

#include <zircon/syscalls.h>

zx_status_t zx_vmar_unmap_handle_close_thread_exit(zx_handle_t vmar_handle,
                                                   zx_vaddr_t addr,
                                                   size_t size,
                                                   zx_handle_t close_handle);

Description

zx_vmar_unmap_handle_close_thread_exit() does a sequence of three operations:

  1. zx_vmar_unmap(vmar_handle, addr, size)
  2. zx_handle_close(close_handle)
  3. zx_thread_exit()

The expectation is that the first operation unmaps a region including the calling thread's own stack. (It's not required, but it's permitted.) This is valid for this call, though it would be invalid for zx_vmar_unmap() or any other call.

If the zx_vmar_unmap() operation is successful, then this call never returns. If close_handle is an invalid handle so that the zx_handle_close() operation fails, then the thread takes a trap (as if by __builtin_trap();).

Rights

TODO(https://fxbug.dev/42107318)

Return value

zx_vmar_unmap_handle_close_thread_exit() does not return on success.

Errors

Same as zx_vmar_unmap().

Notes

The intended use for this is for a dying thread to unmap its own stack, close its own thread handle, and exit. The thread handle cannot be closed beforehand because closing the last handle to a thread kills that thread. The stack cannot be unmapped beforehand because the thread must have some stack space on which to make its final system calls.

This call is used for detached threads, while zx_futex_wake_handle_close_thread_exit() is used for joinable threads.

See also