Re: io_cancel return value change

[Jeff Moyer <jmoyer@redhat.com>]

Benjamin LaHaise <bcrl@kvack.org> writes:

> Cancellation is inherently racy.  It is and always has been possible for 
> an attempt at cancellation to fail, or for the attempt at cancellation to 
> suceed in the bigger picture yet have the io_cancel() call fail (and cause 
> an event to be delivered).  Applications always have and always will have 
> to handle an io_cancel() call potentially failing with the kernel delivering 
> a completion event.  You have to read the io_cancel() man page with that 
> understanding in place.

Sorry, Ben, Zach just pointed out what I was so obviously missing.  From
the changelog:

   This gets rid of the unused io_event argument to kiocb_cancel() and
   kiocb->ki_cancel(), and changes io_cancel() to return -EINPROGRESS if
   kiocb->ki_cancel() returned success.

Somehow I managed to skip right over that change to return
-EINPROGRESS.  *facepalm*

Cheers,
Jeff