linux-kernel - Re: [PATCH] arch/x86/boot: sizeof macro

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Date:   Sun, 31 Dec 2017 08:33:09 -0800
From:   Joe Perches <joe@...ches.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Ingo Molnar <mingo@...nel.org>
Cc:     Saidgani Musaev <cpu808694@...il.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arch/x86/boot: sizeof macro

On Sun, 2017-12-31 at 13:48 +0200, Andy Shevchenko wrote:
> On Fri, Dec 29, 2017 at 9:46 PM, Ingo Molnar <mingo@...nel.org> wrote:
> > * Andy Shevchenko <andy.shevchenko@...il.com> wrote:
> > > > -       ireg.cx  = sizeof buf;
> > > > +       ireg.cx  = sizeof(buf);
> > > 
> > > sizeof is operator, not a function.
> > > So, what are you trying to achieve?
> > 
> > That's true, but in the kernel coding style we use it as a function:
> 
> Yeah, the question is do we need to change all those 177 occurrences at all?

There's actually around 900, for ~100:1 ratio

$ git grep -P "\bsizeof\s+\w" -- "*.[ch]" | wc -l
907
$ git grep -P "\bsizeof\s*\(" -- "*.[ch]" | wc -l
117203

About half of these occurrences are in 3 paths
and their actual uses of sizeof without and with
parenthesis are:

drivers/infiniband/	212:3696
drivers/media/		111:5058
drivers/usb/		121:2006

> Or perhaps it might be an opportunity during some other changes to
> certain users...

Perhaps best that way.