From mboxrd@z Thu Jan  1 00:00:00 1970
From: "tiejun.chen" <tiejun.chen@windriver.com>
Subject: Re: [RFC PATCH v2 1/6] kvm: add device control API
Date: Wed, 3 Apr 2013 09:42:41 +0800
Message-ID: <515B8911.1030706@windriver.com>
References: <1360820960-12537-1-git-send-email-scottwood@freescale.com> <1364856473-25245-1-git-send-email-scottwood@freescale.com> <1364856473-25245-2-git-send-email-scottwood@freescale.com> <515A81ED.9060106@windriver.com> <1364923807.24520.2@snotra> <515B85A1.4000602@windriver.com> <1364952853.8690.3@snotra>
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Cc: Alexander Graf <agraf@suse.de>, <kvm-ppc@vger.kernel.org>,
	<kvm@vger.kernel.org>, <paulus@samba.org>
To: Scott Wood <scottwood@freescale.com>
Return-path: <kvm-ppc-owner@vger.kernel.org>
In-Reply-To: <1364952853.8690.3@snotra>
Sender: kvm-ppc-owner@vger.kernel.org
List-Id: kvm.vger.kernel.org

On 04/03/2013 09:34 AM, Scott Wood wrote:
> On 04/02/2013 08:28:01 PM, tiejun.chen wrote:
>> On 04/03/2013 01:30 AM, Scott Wood wrote:
>>> On 04/02/2013 01:59:57 AM, tiejun.chen wrote:
>>>> On 04/02/2013 06:47 AM, Scott Wood wrote:
>>>>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
>>>>> index ff71541..ed033c0 100644
>>>>> --- a/virt/kvm/kvm_main.c
>>>>> +++ b/virt/kvm/kvm_main.c
>>>>> @@ -2158,6 +2158,17 @@ out:
>>>>>   }
>>>>>   #endif
>>>>>
>>>>> +static int kvm_ioctl_create_device(struct kvm *kvm,
>>>>> +                   struct kvm_create_device *cd)
>>>>> +{
>>>>> +    bool test = cd->flags & KVM_CREATE_DEVICE_TEST;
>>>>> +
>>>>> +    switch (cd->type) {
>>>>> +    default:
>>>>> +        return -ENODEV;
>>>>> +    }
>>>>
>>>> Even after apply patch 5, looks here still misses something like:
>>>>
>>>>     if (test)
>>>>         WARN_ON_ONCE(!cd->type);
>>>
>>> Why?  How does userspace passing in a bad type value mean the kernel needs to
>>> report internal badness, why is a value of zero worse than any other bad value,
>>> and why only when the test flag is set?
>>
>> I just mean we need do something here since looks the 'test' variable is
>> defined but unused, right? But please correct this as you expect :)
>
> Yes, it's unused in this patch, but is used after patch 5 is applied.  I didn't
> think it was worth adding a temporary unused annotation, since this part of the
> kernel doesn't use -Werror.

Yes, its accepted in !-Werror case if we shouldn't warn something as you said.

Tiejun