Re: [RESEND PATCH 1/2] fpga: dfl: pci: reduce the scope of variable 'ret'

[Tom Rix <trix@xxxxxxxxxx>]

Ok, i take your point on the api.

However I still feel that this change should be improved so the return is not defined inside a block.

I think this could be done better with

int ret = num_vfs;

...

return ret;

There is no consistency on this check with the other drivers' sriov_configure.

I do not feel strongly about this change, your original change will work. So you may add.

Reviewed-by: Tom Rix <trix@xxxxxxxxxx>

Tom

On 7/9/20 10:16 PM, Xu Yilun wrote:
> On Thu, Jul 09, 2020 at 06:18:18AM -0700, Tom Rix wrote:
>> I think a better change is to use the ret variable, like this
>>
>> --- a/drivers/fpga/dfl-pci.c
>> +++ b/drivers/fpga/dfl-pci.c
>> @@ -312,7 +312,7 @@ static int cci_pci_sriov_configure(struct pci_dev *pcidev, int num_vfs)
>>                 }
>>         }
>>  
>> -       return num_vfs;
>> +       return ret;
>>  }
>>
>> The existing use of returning num_vfs is not right, the function should return 0/err not num_vfs. currently it is reusing the 0 passed in with num_vfs to mean disable as the 0 return status.  it should be properly returning ret.
> The sriov_configure callback should return negative value for error, and
> return num_vfs if success.
>
> See the Documentation/PCI/pci-iov-howto.rst
>
> also in drivers/pci/iov.c:
>
>   static ssize_t sriov_numvfs_store(struct device *dev, ...)
>   {
> 	...
>
>         ret = pdev->driver->sriov_configure(pdev, num_vfs);
>         if (ret < 0) 
>                 goto exit;
>
>         if (ret != num_vfs)
>                 pci_warn(pdev, "%d VFs requested; only %d enabled\n",
>                          num_vfs, ret);
>
> 	...
>   }
>
>> Tom
>>
>> On 7/9/20 1:12 AM, Xu Yilun wrote:
>>> This is to fix lkp cppcheck warnings:
>>>
>>>  drivers/fpga/dfl-pci.c:230:6: warning: The scope of the variable 'ret' can be reduced. [variableScope]
>>>     int ret = 0;
>>>         ^
>>>
>>>  drivers/fpga/dfl-pci.c:230:10: warning: Variable 'ret' is assigned a value that is never used. [unreadVariable]
>>>     int ret = 0;
>>>             ^
>>>
>>> Fixes: 3c2760b78f90 ("fpga: dfl: pci: fix return value of cci_pci_sriov_configure")
>>> Reported-by: kbuild test robot <lkp@xxxxxxxxx>
>>> Signed-off-by: Xu Yilun <yilun.xu@xxxxxxxxx>
>>> Acked-by: Wu Hao <hao.wu@xxxxxxxxx>
>>> ---
>>>  drivers/fpga/dfl-pci.c | 3 ++-
>>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/fpga/dfl-pci.c b/drivers/fpga/dfl-pci.c
>>> index 4a14a24..73b5153 100644
>>> --- a/drivers/fpga/dfl-pci.c
>>> +++ b/drivers/fpga/dfl-pci.c
>>> @@ -285,7 +285,6 @@ static int cci_pci_sriov_configure(struct pci_dev *pcidev, int num_vfs)
>>>  {
>>>  	struct cci_drvdata *drvdata = pci_get_drvdata(pcidev);
>>>  	struct dfl_fpga_cdev *cdev = drvdata->cdev;
>>> -	int ret = 0;
>>>  
>>>  	if (!num_vfs) {
>>>  		/*
>>> @@ -297,6 +296,8 @@ static int cci_pci_sriov_configure(struct pci_dev *pcidev, int num_vfs)
>>>  		dfl_fpga_cdev_config_ports_pf(cdev);
>>>  
>>>  	} else {
>>> +		int ret;
>>> +
>>>  		/*
>>>  		 * before enable SRIOV, put released ports into VF access mode
>>>  		 * first of all.