[PATCH] dma-buf: Don't use typeof in va_arg

[PATCH] dma-buf: Don't use typeof in va_arg

[Wan Jiabing]

Fix following coccicheck warning:
./drivers/dma-buf/st-dma-fence-unwrap.c:75:39-45: ERROR: reference preceded by free on line 70

Use 'struct dma_fence *' instead of 'typeof(*fences)' to avoid this
warning and also fix other 'typeof(*fences)' to make them consistent.

Fixes: 0c5064fa8d5a ("dma-buf: cleanup dma_fence_unwrap selftest v2")
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
---
 drivers/dma-buf/st-dma-fence-unwrap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c b/drivers/dma-buf/st-dma-fence-unwrap.c
index 4105d5ea8dde..1137a6d90b32 100644
--- a/drivers/dma-buf/st-dma-fence-unwrap.c
+++ b/drivers/dma-buf/st-dma-fence-unwrap.c
@@ -56,7 +56,7 @@ static struct dma_fence *mock_array(unsigned int num_fences, ...)
 
 	va_start(valist, num_fences);
 	for (i = 0; i < num_fences; ++i)
-		fences[i] = va_arg(valist, typeof(*fences));
+		fences[i] = va_arg(valist, struct dma_fence *);
 	va_end(valist);
 
 	array = dma_fence_array_create(num_fences, fences,
@@ -72,7 +72,7 @@ static struct dma_fence *mock_array(unsigned int num_fences, ...)
 error_put:
 	va_start(valist, num_fences);
 	for (i = 0; i < num_fences; ++i)
-		dma_fence_put(va_arg(valist, typeof(*fences)));
+		dma_fence_put(va_arg(valist, struct dma_fence *));
 	va_end(valist);
 	return NULL;
 }
-- 
2.36.1

Re: [PATCH] dma-buf: Don't use typeof in va_arg

[Christian König]

Am 10.06.22 um 09:20 schrieb Wan Jiabing:
> Fix following coccicheck warning:
> ./drivers/dma-buf/st-dma-fence-unwrap.c:75:39-45: ERROR: reference preceded by free on line 70
>
> Use 'struct dma_fence *' instead of 'typeof(*fences)' to avoid this
> warning and also fix other 'typeof(*fences)' to make them consistent.

Well that doesn't looks correct to me.

*fence should be valid at this point, why does coccicheck things it is 
freed?

Regards,
Christian.

>
> Fixes: 0c5064fa8d5a ("dma-buf: cleanup dma_fence_unwrap selftest v2")
> Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
> ---
>   drivers/dma-buf/st-dma-fence-unwrap.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c b/drivers/dma-buf/st-dma-fence-unwrap.c
> index 4105d5ea8dde..1137a6d90b32 100644
> --- a/drivers/dma-buf/st-dma-fence-unwrap.c
> +++ b/drivers/dma-buf/st-dma-fence-unwrap.c
> @@ -56,7 +56,7 @@ static struct dma_fence *mock_array(unsigned int num_fences, ...)
>   
>   	va_start(valist, num_fences);
>   	for (i = 0; i < num_fences; ++i)
> -		fences[i] = va_arg(valist, typeof(*fences));
> +		fences[i] = va_arg(valist, struct dma_fence *);
>   	va_end(valist);
>   
>   	array = dma_fence_array_create(num_fences, fences,
> @@ -72,7 +72,7 @@ static struct dma_fence *mock_array(unsigned int num_fences, ...)
>   error_put:
>   	va_start(valist, num_fences);
>   	for (i = 0; i < num_fences; ++i)
> -		dma_fence_put(va_arg(valist, typeof(*fences)));
> +		dma_fence_put(va_arg(valist, struct dma_fence *));
>   	va_end(valist);
>   	return NULL;
>   }

Re: [PATCH] dma-buf: Don't use typeof in va_arg

[Jiabing Wan]

On 2022/6/10 15:24, Christian König wrote:
> Am 10.06.22 um 09:20 schrieb Wan Jiabing:
>> Fix following coccicheck warning:
>> ./drivers/dma-buf/st-dma-fence-unwrap.c:75:39-45: ERROR: reference 
>> preceded by free on line 70
>>
>> Use 'struct dma_fence *' instead of 'typeof(*fences)' to avoid this
>> warning and also fix other 'typeof(*fences)' to make them consistent.
>
> Well that doesn't looks correct to me.
>
> *fence should be valid at this point, why does coccicheck things it is 
> freed?

*fence is valid. Coccicheck reports this because fence is freed.
But use 'struct dma_fence *' can avoid this wrong report.

I also grep all code and find it's unusual to use 'typeof' in va_arg, 
only two files.

grep -R "va_arg("  . | grep 'typeof'
./drivers/dma-buf/st-dma-fence-unwrap.c:                fences[i] = 
va_arg(valist, typeof(*fences));
./drivers/dma-buf/st-dma-fence-unwrap.c: dma_fence_put(va_arg(valist, 
typeof(*fences)));
./lib/test_scanf.c:             typeof(*expect) got = *va_arg(ap, 
typeof(expect));              \

And other files all use declaration name directly.
So I send this patch makes code clearer and fix the wrong warning by the 
way.

Thanks,
Wan Jiabing

>
> Regards,
> Christian.
>
>>
>> Fixes: 0c5064fa8d5a ("dma-buf: cleanup dma_fence_unwrap selftest v2")
>> Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
>> ---
>>   drivers/dma-buf/st-dma-fence-unwrap.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c 
>> b/drivers/dma-buf/st-dma-fence-unwrap.c
>> index 4105d5ea8dde..1137a6d90b32 100644
>> --- a/drivers/dma-buf/st-dma-fence-unwrap.c
>> +++ b/drivers/dma-buf/st-dma-fence-unwrap.c
>> @@ -56,7 +56,7 @@ static struct dma_fence *mock_array(unsigned int 
>> num_fences, ...)
>>         va_start(valist, num_fences);
>>       for (i = 0; i < num_fences; ++i)
>> -        fences[i] = va_arg(valist, typeof(*fences));
>> +        fences[i] = va_arg(valist, struct dma_fence *);
>>       va_end(valist);
>>         array = dma_fence_array_create(num_fences, fences,
>> @@ -72,7 +72,7 @@ static struct dma_fence *mock_array(unsigned int 
>> num_fences, ...)
>>   error_put:
>>       va_start(valist, num_fences);
>>       for (i = 0; i < num_fences; ++i)
>> -        dma_fence_put(va_arg(valist, typeof(*fences)));
>> +        dma_fence_put(va_arg(valist, struct dma_fence *));
>>       va_end(valist);
>>       return NULL;
>>   }
>

Re: [PATCH] dma-buf: Don't use typeof in va_arg

[Christian König]

Am 10.06.22 um 09:52 schrieb Jiabing Wan:
>
>
> On 2022/6/10 15:24, Christian König wrote:
>> Am 10.06.22 um 09:20 schrieb Wan Jiabing:
>>> Fix following coccicheck warning:
>>> ./drivers/dma-buf/st-dma-fence-unwrap.c:75:39-45: ERROR: reference 
>>> preceded by free on line 70
>>>
>>> Use 'struct dma_fence *' instead of 'typeof(*fences)' to avoid this
>>> warning and also fix other 'typeof(*fences)' to make them consistent.
>>
>> Well that doesn't looks correct to me.
>>
>> *fence should be valid at this point, why does coccicheck things it 
>> is freed?
>
> *fence is valid. Coccicheck reports this because fence is freed.
> But use 'struct dma_fence *' can avoid this wrong report.

Well in this case that's just a clear NAK.

Using typeof(*var) is perfectly valid and preferred should the type 
change at some point.

As far as I can see your cocci script is somehow reporting a false warning.

Regards,
Christian.

>
> I also grep all code and find it's unusual to use 'typeof' in va_arg, 
> only two files.
>
> grep -R "va_arg("  . | grep 'typeof'
> ./drivers/dma-buf/st-dma-fence-unwrap.c:                fences[i] = 
> va_arg(valist, typeof(*fences));
> ./drivers/dma-buf/st-dma-fence-unwrap.c: dma_fence_put(va_arg(valist, 
> typeof(*fences)));
> ./lib/test_scanf.c:             typeof(*expect) got = *va_arg(ap, 
> typeof(expect));              \
>
> And other files all use declaration name directly.
> So I send this patch makes code clearer and fix the wrong warning by 
> the way.
>
> Thanks,
> Wan Jiabing
>
>>
>> Regards,
>> Christian.
>>
>>>
>>> Fixes: 0c5064fa8d5a ("dma-buf: cleanup dma_fence_unwrap selftest v2")
>>> Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
>>> ---
>>>   drivers/dma-buf/st-dma-fence-unwrap.c | 4 ++--
>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c 
>>> b/drivers/dma-buf/st-dma-fence-unwrap.c
>>> index 4105d5ea8dde..1137a6d90b32 100644
>>> --- a/drivers/dma-buf/st-dma-fence-unwrap.c
>>> +++ b/drivers/dma-buf/st-dma-fence-unwrap.c
>>> @@ -56,7 +56,7 @@ static struct dma_fence *mock_array(unsigned int 
>>> num_fences, ...)
>>>         va_start(valist, num_fences);
>>>       for (i = 0; i < num_fences; ++i)
>>> -        fences[i] = va_arg(valist, typeof(*fences));
>>> +        fences[i] = va_arg(valist, struct dma_fence *);
>>>       va_end(valist);
>>>         array = dma_fence_array_create(num_fences, fences,
>>> @@ -72,7 +72,7 @@ static struct dma_fence *mock_array(unsigned int 
>>> num_fences, ...)
>>>   error_put:
>>>       va_start(valist, num_fences);
>>>       for (i = 0; i < num_fences; ++i)
>>> -        dma_fence_put(va_arg(valist, typeof(*fences)));
>>> +        dma_fence_put(va_arg(valist, struct dma_fence *));
>>>       va_end(valist);
>>>       return NULL;
>>>   }
>>
>