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

[Markus Armbruster]

Marcel Apfelbaum <address@hidden> writes:

> 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.

I'll give it a try when I respin.  Thanks!