Re: +checkpatch-add-check-for-use-of-sizeof-without-parenthesis.patch added to-mm tree

[Joe Perches]

On Mon, 2012-07-09 at 16:47 -0700, David Rientjes wrote:
> On Mon, 9 Jul 2012, Joe Perches wrote:
> 
> > > So, nack, don't start enforcing your own coding style and preferences in 
> > > checkpatch.pl.
> > 
> > Not just my opinion.
> > 
> > https://lkml.org/lkml/2008/12/23/138
> > --------------------------------------------------------
> > Date: Tue, 23 Dec 2008 10:08:50 -0800 (PST)
> > From: Linus Torvalds <>
> > []
> > Another example of this is "sizeof". The kernel universally (I hope) has 
> > parenthesis around the sizeof argument, even though it's clearly not 
> > required by the C language. 
> > 
> 
> Well, let's add Linus to the cc then because it's certainly not a C 
> standard.  The sizeof operator requires parenthesis for type names, you 
> can't do "sizeof unsigned long", for example, it requires 
> "sizeof (unsigned long)".  All other unary operators do not need the 
> parenthesis by ANY C standard.
> 
> Documentation/CodingStyle does not ask for the parenthesis to be added 
> just like it doesn't ask for parenthesis to do things like (i++); which is 
> another unary operator.

CodingStyle already does suggest parenthesis around sizeof

3.1:  Spaces

Linux kernel style for use of spaces depends (mostly) on
function-versus-keyword usage.  Use a space after (most) keywords.  The
notable exceptions are sizeof, typeof, alignof, and __attribute__, which look
somewhat like functions (and are usually used with parentheses in Linux,
although they are not required in the language, as in: "sizeof info" after
"struct fileinfo info;" is declared).

So use a space after these keywords:
	if, switch, case, for, do, while
but not with sizeof, typeof, alignof, or __attribute__.  E.g.,
	s = sizeof(struct file);

and

Chapter 14: Allocating memory
[]
The preferred form for passing a size of a struct is the following:

	p = kmalloc(sizeof(*p), ...);


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