linux-kernel - Re: [PATCH -next 005/491] ARM/UNIPHIER ARCHITECTURE: Use fallthrough;

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Date:   Thu, 12 Mar 2020 07:15:23 -0700
From:   Joe Perches <joe@...ches.com>
To:     "Theodore Y. Ts'o" <tytso@....edu>
Cc:     Masahiro Yamada <masahiroy@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, linux-serial@...r.kernel.org,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next 005/491] ARM/UNIPHIER ARCHITECTURE: Use
 fallthrough;

On Thu, 2020-03-12 at 09:47 -0400, Theodore Y. Ts'o wrote:
> On Thu, Mar 12, 2020 at 02:37:31AM -0700, Joe Perches wrote:
> > As I have suggested a few times, better still
> > would be to have a mechanism for scripted patches
> > applied possibly as single treewide patch.
> > 
> > Likely applied only at an -rc1.
> > 
> > The stated negatives to a treewide mechanism
> > have been difficulty to backport to -stable.
> 
> Any time we do a massive, disruptive change to the code base, it's
> going to cause problems to -stable.  It means that bug fix patches
> won't necessarily auto-apply, and some will require manual fixups
> afterwards

That's mostly a tools problem than a real problem.

> Given that this change doesn't really fix any bugs, I'd have to ask
> the question --- is it *worth* it?  We really need to apply a certain
> amount of cost/benefit analysis around this.
> 
> If it were really important, the thing we could do is to apply a
> single treewide patch at some point after the merge window.  I'd
> suggest after -rc2, myself, but reasonable people can differ.  And
> then, if it were *really* important we could run the same script on
> the stable kernels.
> 
> But for changing "/* fallthrough */" to "fallthrough;"
> 
> Does this ***really*** matter?

That depends a bit on whether clang is your
compiler of choice.

> Why are we tying ourselves up in knots
> trying to do this all at once?

Discretely or treewide, all at once or done over time,
the impact problem to backports is the same.