[alsa-devel] [patch 1/2] ALSA: oxfw: some signedness bugs

[Takashi Iwai]

At Sat, 13 Dec 2014 19:14:46 +0900,
Takashi Sakamoto wrote:
> 
> On Dec 13 2014 16:04, Dan Carpenter wrote:
> > On Sat, Dec 13, 2014 at 02:06:59PM +0900, Takashi Sakamoto wrote:
> >> On Dec 13 2014 04:27, Dan Carpenter wrote:
> >>> This code tends to use unsigned variables by default and it causes
> >>> signedness bugs when we use negative variables for error handling.
> >>> The "i" and "j" variables are used to iterated over small positive
> >>> values and so they should be type "int".  The "len" variable doesn't
> >>> *need* to be signed but it should be signed to make the code easier to
> >>> read and audit.
> >>>
> >>> Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
> >>
> >> Thanks, but I prefer to use 'unsigned int' for loop counter, like the
> >> other drivers.
> > 
> > Unthinking use of unsigned int every where is a kind of leprosy.  It
> > just makes the code hard to read and it causes bugs.
> 
> In the beginning of last year, I received a comment from Clemens to use
> 'unsigned int' type for loop counter instead of 'int' type. Since then,
> for ALSA firewire stack, I've been following his advice. (but actually I
> missed to OXFW driver...)
> 
> For consistency inner this stack, I request you to follow this.

Note that Dan's suggestions are about the variables like "i" and "j".
These are used normally for small loop counts, and they are int in a
standard idiom.  If they are declared as another type, you force
reader's attention *unnecessarily*, and it decreases the readability
(i.e. they have to read the loop code as somewhat special even if
it's a normal loop).  This is the only big drawback, and the rest
merit/demerit are almost ignorable, IMO.

Of course, in some cases, a loop count might be better in unsigned.
But then a different variable name should be used instead.

After all, this is rather a minor issue, almost a bikeshed topic, so I
didn't care much while reviewing your patches, and I still don't care
whether this fix patch will have int or unsigned for i.  But, it'd be
good if you keep this information in your mind, at least.


thanks,

Takashi