linux-kernel - Re: [PATCH 04/29] memstick: core: rework state machines

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Message-ID: <1288056863.4024.66.camel@maxim-laptop>
Date:	Tue, 26 Oct 2010 03:34:23 +0200
From:	Maxim Levitsky <maximlevitsky@...il.com>
To:	Alex Dubov <oakad@...oo.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 04/29] memstick: core: rework state machines

On Mon, 2010-10-25 at 08:01 -0700, Alex Dubov wrote:
> --- On Fri, 22/10/10, Maxim Levitsky <maximlevitsky@...il.com> wrote:
> 
> > From: Maxim Levitsky <maximlevitsky@...il.com>
> > Subject: [PATCH 04/29] memstick: core: rework state machines
> > To: "Alex Dubov" <oakad@...oo.com>
> > Cc: "Andrew Morton" <akpm@...ux-foundation.org>, "LKML" <linux-kernel@...r.kernel.org>, "Maxim Levitsky" <maximlevitsky@...il.com>
> > Received: Friday, 22 October, 2010, 4:53 PM
> > Make state machines in memstick core
> > follow the
> > new style.
> > 
> 
> 1. This is an important functional patch. At present, "new style" exists
> only in your head. You should make an effort to justify it to everybody
> else by providing a rationale in patch description.
I already explained that.
Ok. I add that explanation to patch header.


> 
> 2. You are using an integer state variable (instead of function pointers
> which were self-describing by virtue of the referred function names).
> Please, define an enumerated type for this state variable, giving states
> human-readable, descriptive names. If you need to do state variable
> arithmetic, you can provide a couple of simple, descriptive macros to
> do so:
> 
> #define NEXT_STATE(s) (s + 1)
Do we have a corporate policy of no magic numbers?
Like this: http://thedailywtf.com/Articles/Avoiding-Magic-Constants.aspx


The issue here (I explained it already) is that I often use card-state
++; to get to next state;
Other the enforcing the policy the suggested #define it won't help.

card->state++ allows me for example to fallback through switch states
and go by default to next state by default without additional code.
If I bury state numbers with #defines or enums, the assumptions that
states appear in switch in ascending order won't be obvious anymore
and nether that adding 1 to state will bring me to next switch case.





> 
> or something along the line.
> 
> 3. Coding style.
Passed checkpatch.pl. Could you show me the lines affected?


Best regards,
	Maxim Levitsky


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