RE: [PATCH 1/5] arch/arm: Correct NULL test

[H Hartley Sweeten]

On Monday, December 28, 2009 9:51 AM, Julia Lawall wrote:
> On Mon, 28 Dec 2009, H Hartley Sweeten wrote:
>
>> On Sunday, December 27, 2009 3:08 PM, Julia Lawall wrote:
>>>>>  	dbgfs_chan = kmalloc(sizeof(*dbgfs_state) * num_dma_channels,
>>>>>  			     GFP_KERNEL);
>>>>> -	if (!dbgfs_state)
>>>>> +	if (!dbgfs_chan)
>>>>>  		goto err_alloc;
>>>> Shouldn't the malloc line read:
>>>> 
>>>> 	... = kmalloc(sizeof(*dbgfs_chan) * ...)
>>>> 	                      ^^^^^^^^^^
>>>> 
>>>> ?
>>>
>>> Good point, thanks.  I will send a revised patch.
>> 
>> Wouldn't this be clearer?
>> 
>> 	... = kmalloc(sizeof(struct dentry) * ...)
>
> Documentation/CodingStyle thinks otherwise:
>
> "The preferred form for passing a size of a struct is the following:
>
> 	p = kmalloc(sizeof(*p), ...);
>
> The alternative form where struct name is spelled out hurts readability 
> and introduces an opportunity for a bug when the pointer variable type is 
> changed but the corresponding sizeof that is passed to a memory allocator 
> is not."
>
> And actually, in this case, sizeof(struct dentry) would be wrong, because 
> the type of dbgfs_chan is struct dentry **, not struct dentry *.  What is 
> wanted is an array of pointers.

Ah, missed that.  Thanks for pointing it out.

Regards,
Hartley
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/