Re: Input: add MAX7359 key switch controller driver

[Kim Kyuwon <chammoru@gmail.com>]

On Sat, May 9, 2009 at 12:36 PM, Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
> Hi Kim,
>
> On Friday 08 May 2009 18:58:45 Kim Kyuwon wrote:
>> By the way, can I ask the same question which I ask to Trilok.
>> Even though I guard suspend/resume with #ifdef CONFIG_PM in the new
>> patch, Could I know the good reason for this protection? Because
>> '/Documentation/SubmittingPatches' says "ifdefs are ugly"
>
> If kernel is compiled without CONFIG_PM then these functions would
> be just dead weight. Generally speaking, #ifdefs are considered ugly
> if they are in the middle of function code, affecting logic. But to
> to compile out unneeded functionality they are OK. That's why you
> often see in the kernel
>
> #ifdef CONFIG_BAZ
> void do_baz()
> {
>        .. real code ..
> }
> #else
> void do_baz()
> {
> }
> #endif
>
> and then...
>
> int foo()
> {
>        bar1();
>        bar2();
>        do_baz();
>        bar3();
> }
>
>
> As you can see, foo()'s logic stays the same, there are no #ifdefs
> cluttering it, but baz code either executed or not.
>
> Hope this helps.

Thank you for your kind explanation. It is very helpful to me and my colleagues.

Kyuwon