linux-kernel - Re: [PATCH] kgdb: fix gcc-11 warning on indentation

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Date:   Mon, 22 Mar 2021 12:22:27 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Jason Wessel <jason.wessel@...driver.com>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ingo Molnar <mingo@...e.hu>,
        Christian Brauner <christian.brauner@...ntu.com>,
        kgdb-bugreport@...ts.sourceforge.net,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kgdb: fix gcc-11 warning on indentation

Hi,

On Mon, Mar 22, 2021 at 11:19 AM Arnd Bergmann <arnd@...nel.org> wrote:
>
> On Mon, Mar 22, 2021 at 6:07 PM Doug Anderson <dianders@...omium.org> wrote:
> > On Mon, Mar 22, 2021 at 9:43 AM Arnd Bergmann <arnd@...nel.org> wrote:
> > >
> > > -#define v1printk(a...) do { \
> > > -       if (verbose) \
> > > -               printk(KERN_INFO a); \
> > > -       } while (0)
> > > -#define v2printk(a...) do { \
> > > -       if (verbose > 1) \
> > > -               printk(KERN_INFO a); \
> > > -               touch_nmi_watchdog();   \
> > > -       } while (0)
> > > -#define eprintk(a...) do { \
> > > -               printk(KERN_ERR a); \
> > > -               WARN_ON(1); \
> > > -       } while (0)
> > > +#define v1printk(a...) do {            \
> >
> > nit: In addition to the indentation change you're also lining up the
> > backslashes. Is that just personal preference, or is there some
> > official recommendation in the kernel? I don't really have a strong
> > opinion either way (IMO each style has its advantages).
>
> I don't think there is an official recommendation, I just think the
> style is more common, and it helped my figure out what the
> indentation should look like in this case.

OK, makes sense. I just wasn't sure if there was some standard that I
wasn't aware of. Given that you have to touch all these lines anyway
then making them all pretty like this seems fine to me.


> > > +       if (verbose)                    \
> > > +               printk(KERN_INFO a);    \
> > > +} while (0)
> > > +#define v2printk(a...) do {            \
> > > +       if (verbose > 1)                \
> > > +               printk(KERN_INFO a);    \
> > > +       touch_nmi_watchdog();           \
> >
> > This touch_nmi_watchdog() is pretty wonky. I guess maybe the
> > assumption is that the "verbose level 2" prints are so chatty that the
> > printing might prevent us from touching the NMI watchdog in the way
> > that we normally do and thus we need an extra one here?
> >
> > ...but, in that case, I think the old code was _wrong_ and that the
> > intention was that the touch_nmi_watchdog() should only be if "verose
> > > 1" as the indentation implied. There doesn't feel like a reason to
> > touch the watchdog if we're not doing anything slow.
>
> No idea. It was like this in Jason's original version from 2008.

Yeah, I noticed the same. I'd be curious what Daneil (or Jason if he's
reading) says. I suppose i could always wait until your patch lands
and then send a new patch that puts it inside the "if" statement and
we can debate it then.

-Doug