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From: Markus Armbruster <armbru@redhat.com>
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Date: Fri, 19 Jun 2015 15:19:17 +0200
In-Reply-To: <55840F46.7000009@suse.de> ("Andreas =?utf-8?Q?F=C3=A4rber=22?=
	=?utf-8?Q?'s?= message of "Fri, 19 Jun 2015 14:47:02 +0200")
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Subject: Re: [Qemu-devel] [PATCH v2 3/7] qdev-monitor: Stop error avalance
	in qbus_find_recursive()
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To: Andreas =?utf-8?Q?F=C3=A4rber?= <afaerber@suse.de>
Cc: pbonzini@redhat.com, qemu-devel@nongnu.org, kraxel@redhat.com

Andreas F=C3=A4rber <afaerber@suse.de> writes:

> Did you mean avalanche?

Yes, fixing...

> Am 13.06.2015 um 13:18 schrieb Markus Armbruster:
>> Reproducer:
>>=20
>>     $ qemu-system-x86_64 -nodefaults -device virtio-rng-pci -device virt=
io-rng-pci -device virtio-rng-device,bus=3Dvirtio-bus
>>     qemu-system-x86_64: -device virtio-rng-device,bus=3Dvirtio-bus: Bus =
'virtio-bus' is full
>>     qemu-system-x86_64: -device virtio-rng-device,bus=3Dvirtio-bus: Bus =
'virtio-bus' is full
>>     qemu-system-x86_64: -device virtio-rng-device,bus=3Dvirtio-bus: Bus =
'virtio-bus' not found
>>=20
>> qbus_find_recursive() reports the "is full" error itself, and leaves
>> reporting "not found" to its caller.  The result is confusion.  Write
>> it a function contract that permits leaving all error reporting to the
>> caller, and implement it.  Update callers to detect and report "is
>> full".
>>=20
>> Screwed up when commit 1395af6 added the max_dev limit and the "is
>> full" error condition to enforce it.
>>=20
>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>> Reviewed-by: Eric Blake <eblake@redhat.com>
>> ---
>>  qdev-monitor.c | 62 ++++++++++++++++++++++++++++++++++++---------------=
-------
>>  1 file changed, 39 insertions(+), 23 deletions(-)
>>=20
>> diff --git a/qdev-monitor.c b/qdev-monitor.c
>> index 7dd62dd..1408c86 100644
>> --- a/qdev-monitor.c
>> +++ b/qdev-monitor.c
>> @@ -364,43 +364,55 @@ static DeviceState *qbus_find_dev(BusState *bus, c=
har *elem)
>>      return NULL;
>>  }
>>=20=20
>> +static inline bool qbus_is_full(BusState *bus)
>> +{
>> +    BusClass *bus_class =3D BUS_GET_CLASS(bus);
>> +    return bus_class->max_dev && bus->max_index >=3D bus_class->max_dev;
>> +}
>> +
>> +/**
>
> This should probably just be "/*".

Fixing...

> I'll trust you on getting the functional logic right, can't do a full
> review right now.

Thank you all the same!