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Date: Thu, 11 Jan 2024 15:42:19 -0800
From: Kees Cook <keescook@chromium.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Kent Overstreet <kent.overstreet@linux.dev>,
	linux-bcachefs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [GIT PULL] bcachefs updates for 6.8
Message-ID: <202401111534.859084884C@keescook>
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On Thu, Jan 11, 2024 at 10:57:18PM +0000, Matthew Wilcox wrote:
> On Wed, Jan 10, 2024 at 05:47:20PM -0800, Linus Torvalds wrote:
> > No, because the whole idea of "let me mark something deprecated and
> > then not just remove it" is GARBAGE.
> > 
> > If somebody wants to deprecate something, it is up to *them* to finish
> > the job. Not annoy thousands of other developers with idiotic
> > warnings.
> 
> What would be nice is something that warned about _new_ uses being
> added.  ie checkpatch.  Let's at least not make the problem worse.

For now, we've just kind of "dealt with it". For things that show up
with new -W options we've enlisted sfr to do the -next builds with it
explicitly added (but not to the tree) so he could generate nag emails
when new warnings appeared. That could happen if we added it to W=1
builds, or some other flag like REPORT_DEPRECATED=1.

Another ugly idea would be to do a treewide replacement of "func" to
"func_deprecated", and make "func" just a wrapper for it that is marked
with __deprecated. Then only new instances would show up (assuming people
weren't trying to actively bypass the deprecation work by adding calls to
"func_deprecated"). :P Then the refactoring to replace "func_deprecated"
could happen a bit more easily.

Most past deprecations have pretty narrow usage. This is not true with
the string functions, which is why it's more noticeable here. :P

-Kees

-- 
Kees Cook