[PATCH v3 5/6] drm/i915/gvt: Assign NULL to the pointer after memory free.

[Gimbitskii, Aleksei]

Thanks for the reminding and sorry that I forget to mention that.  But we think that if we add this error message here, probably we also need to add the error message in other similar places, which seems a bit over too much. How about we still follow the existing style?

-----Original Message-----
From: Xu, Colin 
Sent: Thursday, April 25, 2019 8:32 AM
To: Gimbitskii, Aleksei <aleksei.gimbitskii at intel.com>
Cc: Zhenyu Wang <zhenyuw at linux.intel.com>; intel-gvt-dev at lists.freedesktop.org; Wang, Zhi A <zhi.a.wang at intel.com>
Subject: Re: [PATCH v3 5/6] drm/i915/gvt: Assign NULL to the pointer after memory free.


On 2019-04-25 11:14, Zhenyu Wang wrote:
> On 2019.04.23 15:04:12 +0300, Aleksei Gimbitskii wrote:
>> The klocwork static code analyzer complains about using pointer after 
>> being freed, because further we pass it to the gvt_vgpu_err() function.
>> Assign pointer to be NULL intentionaly, to meet requirements of the 
>> code analyzer.
>>
>> This patch fixed the issue #648 reported as error by klocwork.
>>
>> Signed-off-by: Aleksei Gimbitskii <aleksei.gimbitskii at intel.com>
>> Cc: Zhenyu Wang <zhenyuw at linux.intel.com>
>> Cc: Zhi Wang <zhi.a.wang at intel.com>
>> ---
>>   drivers/gpu/drm/i915/gvt/gtt.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/gpu/drm/i915/gvt/gtt.c 
>> b/drivers/gpu/drm/i915/gvt/gtt.c index 061499a38f4d..927753a59a1e 
>> 100644
>> --- a/drivers/gpu/drm/i915/gvt/gtt.c
>> +++ b/drivers/gpu/drm/i915/gvt/gtt.c
>> @@ -1106,6 +1106,7 @@ static struct intel_vgpu_ppgtt_spt 
>> *ppgtt_populate_spt_by_guest_entry(
>>   
>>   err_free_spt:
>>   	ppgtt_free_spt(spt);
>> +	spt = NULL;
>>   err:
>>   	gvt_vgpu_err("fail: shadow page %p guest entry 0x%llx type %d\n",
>>   		     spt, we->val64, we->type);
> I think we can remove this error message which doesn't tell the reason 
> to fail at all, but have err message in earlier path where we can 
> indicate the reason.

Seem like miss my comment in v2.

I would suggest add different msg before the two "goto err_free_spt",

then in this err_free_stp label you could just return without print the

same msg as err. Otherwise you can't tell the reason from the same err.

>
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> intel-gvt-dev at lists.freedesktop.org
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--
Best Regards,
Colin Xu

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