Re: [Patch] Staging: winbond: usb_free_urb(NULL) is safe

[Harsh Kumar <harsh1kumar@gmail.com>]

On Thursday 30 May 2013 12:58 PM, Julia Lawall wrote:
> 
> 
> On Thu, 30 May 2013, Harsh Kumar wrote:
> 
>>
>>
>> On Thursday 30 May 2013 10:41 AM, Julia Lawall wrote:
>>>> diff -uprN a/drivers/staging/winbond/wb35reg.c b/drivers/staging/winbond/wb35reg.c
>>>> --- a/drivers/staging/winbond/wb35reg.c	2013-05-28 00:52:26.000000000 +0530
>>>> +++ b/drivers/staging/winbond/wb35reg.c	2013-05-28
> 02:11:35.000000000 +0530
>>>> @@ -64,12 +64,11 @@ unsigned char Wb35Reg_BurstWrite(struct
>>>>
>>>>  		return true;
>>>>  	} else {
>>>> -		if (urb)
>>>> -			usb_free_urb(urb);
>>>> +		usb_free_urb(urb);
>>>
>>> I took a look at this case.  Wouldn't it be nicer to check for failures
>>> one by one, as done almost everywhere else in the kernel?  Then you would
>>> know what had been successfully allocated and what has to be freed.
>>>
>>> julia
>>>
>>>
>>>
>>
>> Do you want that values of urb and reg_queue to be checked separately to see which has
>> failed? That will be more logical. But, then what should be done with the knowledge of
>> what has failed? Should there be a print or should the return value change?
> 
> I don't know much about the driver, so a safe thing to do would be just to
> keep the current semantics.  When the kzalloc fails, just return false.
> When the usb_alloc_urb fails, just kfree and then return false.
> 
> Also, currently there is a return false at the end of the function that is
> dead code.  Perhaps things could be reorganized so that that is not
> necessary.  Usually, after an allocation, the if just takes care of the
> error case, and the fallthrough case continues in the normal way.
> 

Okay, got it. I will reorganize the stuff here.

>> Actually, the return values of these functions like Wb35Reg_BurstWrite() have not
>> been used where these functions are called. Maybe, we need to check whether write &
>> read are successful or not. Maybe, that also needs to be changed.
> 
> I don't know.
> 
> julia