# Re: \[PATCH 3/3\] userfaultfd: non-cooperative: allow synchronous EVENT\_REMOVE

- From: Mike Rapoport \<hidden\>
- Date: 2018-02-28 08:26:23 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2018/02/5194754
- Thread: https://ratatoskr.run/linux-mm/2018/02/5194751/t.md

```text
On Wed, Feb 28, 2018 at 11:21:02AM +0300, Pavel Emelyanov wrote:
> 
> > @@ -52,6 +53,7 @@
> >  #define _UFFDIO_WAKE			(0x02)
> >  #define _UFFDIO_COPY			(0x03)
> >  #define _UFFDIO_ZEROPAGE		(0x04)
> > +#define _UFFDIO_WAKE_SYNC_EVENT		(0x05)
> 
> Excuse my ignorance, but what's the difference between UFFDIO_WAKE and UFFDIO_WAKE_SYNC_EVENT?

UFFDIO_WAKE is used when UFFDIO_COPY/UFFDIO_ZERO page are used with
UFFDIO_*_MODE_DONTWAKE flag set and it presumes 'struct uffdio_range'
argument to the ioctl(). Since waking up a non page fault event requires
different parameters I've add new ioctl to keep backwards compatibility.
 
> -- Pavel
> 

-- 
Sincerely yours,
Mike.
```