Re: [Qemu-devel] [PATCH v2 10/10] qdev: Do not let the user try to device_add when it cannot work

[Marcel Apfelbaum]

On Wed, 2013-10-30 at 13:15 +0100, Markus Armbruster wrote:
> Marcel Apfelbaum <address@hidden> writes:
> 
> > On Tue, 2013-10-29 at 17:08 +0100, address@hidden wrote:
> >> From: Markus Armbruster <address@hidden>
> >> 
> >> Such devices have always been unavailable and omitted from the list of
> >> available devices shown by device_add help.  Until commit 18b6dad
> >> silently broke the former, setting up nasty traps for unwary users,
> >> like this one:
> >> 
> >>     $ qemu-system-x86_64 -nodefaults -monitor stdio -display none
> >>     QEMU 1.6.50 monitor - type 'help' for more information
> >>     (qemu) device_add apic
> >>     Segmentation fault (core dumped)
> >> 
> >> I call that a regression.  Fix it.
> >> 
> >> Signed-off-by: Markus Armbruster <address@hidden>
> >> ---
> >>  qdev-monitor.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >> 
> >> diff --git a/qdev-monitor.c b/qdev-monitor.c
> >> index 36f6f09..c538fec 100644
> >> --- a/qdev-monitor.c
> >> +++ b/qdev-monitor.c
> >> @@ -477,7 +477,7 @@ DeviceState *qdev_device_add(QemuOpts *opts)
> >>          }
> >>      }
> >>  
> >> -    if (!obj) {
> >> +    if (!obj || 
> >> DEVICE_CLASS(obj)->cannot_instantiate_with_device_add_yet) {
> >>          qerror_report(QERR_INVALID_PARAMETER_VALUE, "driver", "device 
> >> type");
> >>          return NULL;
> >>      }
> > Minor comment, if you move the if statement after
> >  k = DEVICE_CLASS(obj);
> > you don't need the cast anymore.
> 
> Ignorant question: does DEVICE_CLASS(NULL) work and return NULL?
Checked it, yes, it will return NULL.

Marcel

> 
> > Seems OK to me.
> > Reviewed-by: Marcel Apfelbaum <address@hidden>
> 
> Thanks!
>