On Jul 27, 2005, at 13:08, Randy Dunlap wrote:
>
>
>> On Jul 25, 2005, at 16:06, Francois Romieu wrote:
>>
>>
>>
>>>> +int mdiobus_register(struct mii_bus *bus)
>>>> +{
>>>> + int i;
>>>> + int err = 0;
>>>> +
>>>> + spin_lock_init(&bus->mdio_lock);
>>>> +
>>>> + if (NULL == bus || NULL == bus->name ||
>>>> + NULL == bus->read ||
>>>> + NULL == bus->write)
>>>>
>>>>
>>>
>>> Be spartan:
>>> if (!bus || !bus->name || !bus->read || !bus->write)
>>>
>>
>>
>> I think we have to agree to disagree here. I could be convinced, but
>> I'm partial to using NULL explicitly.
>>
>
> But there are 2 issues here (at least). One is to use NULL or
> not. The other is using (constant == var) or (var == constant).
>
> It's not described in CodingStlye afaik, but most recent email
> on the subject strongly prefers (var == constant) [in my
> unscientific survey -- of bits in my head].
>
> So using the suggested style will fix both of these. :)
Ok, here I won't agree to disagree with you. !foo as a check for
NULL is a reasonable idea, but not my style. If that's the preferred
style for the kernel, I will do that.
But (var == constant) is a style that asks for errors. By putting
the constant first in these checks, you never run the risk of leaving
a bug like this:
if (dev = NULL)
...
This kind of error is quite frustrating to detect, and the eye will
often miss it when scanning for errors. If you follow constant ==
var, though, then the bug looks like this:
if (NULL = dev)
which is instantly caught by the compiler.
Just my 32 cents
>
>
>>>> + /* Otherwise, we allocate the device, and initialize the
>>>> + * default values */
>>>> + dev = kmalloc(sizeof(*dev), GFP_KERNEL);
>>>> +
>>>> + if (NULL == dev) {
>>>> + errno = -ENOMEM;
>>>> + return NULL;
>>>> + }
>>>> +
>>>> + memset(dev, 0, sizeof(*dev));
>>>>
>>>>
>>>
>>> The kernel provides kcalloc.
>>>
>>
>>
>> I went looking for it, and found it in fs/cifs/misc.c. I'm hesitant
>> to link to a function defined in the filesystem code just to save 1
>> line of code
>>
>
> It's more global than that.
Should we move the function, then, to include/linux/slab.h? Or
somewhere else?
