[Qemu-devel] Re: To O_EXCL or not to O_EXCL open host_cdrom

[Stefan Hajnoczi]

On Mon, Apr 11, 2011 at 10:37:32AM +0530, Amit Shah wrote:
> On (Fri) 08 Apr 2011 [12:33:27], Stefan Hajnoczi wrote:
> > The other concern I have about using O_EXCL is that we expose
> > ourselves to race conditions if there is ever a need to re-open the
> > device.  When QEMU closes its file descriptor another program may be
> > scheduled to run and open the device with O_EXCL.  Now QEMU will not
> > be able to open the CD-ROM anymore.
> 
> The admins should really be the ones worrying about this, not QEMU.

Think of a desktop use case.  virt-manager lets me pass through the host
CD-ROM today.  Desktops have hald/udisks and you can't expect users to
disable/reenable those services just for QEMU.

Stefan