Re: [PATCH 1/3] cleanup: Add cond_guard() to conditional guards

From: Linus Torvalds <torvalds@linux-foundation.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: peterz@infradead.org, gregkh@linuxfoundation.org,
	 Dave Jiang <dave.jiang@intel.com>,
	Ira Weiny <ira.weiny@intel.com>,
	 Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	 "Fabio M. De Francesco"
	<fabio.maria.de.francesco@linux.intel.com>,
	linux-kernel@vger.kernel.org,  linux-cxl@vger.kernel.org
Subject: Re: [PATCH 1/3] cleanup: Add cond_guard() to conditional guards
Date: Tue, 27 Feb 2024 12:49:34 -0800	[thread overview]
Message-ID: <CAHk-=win7bwWhPJ=iuW4h-sDTqbX6v9_LJnMaO3KxVfPSs81bQ@mail.gmail.com> (raw)
In-Reply-To: <170905253339.2268463.9376907713092612237.stgit@dwillia2-xfh.jf.intel.com>

On Tue, 27 Feb 2024 at 08:48, Dan Williams <dan.j.williams@intel.com> wrote:
>
>         cond_guard(mutex_intr, return -EINTR, &mutex);

Again, this is *not* helping make code readable and less likely to have bugs.

The macro has obvious deficiencies, like the "_fail" argument not
being surrounded by  "{ }" (the equivalent of parenthesizing an
expression argument), but even with that trivial fix the syntax is
just too ugly to live, and doesn't match normal C syntax.

And yes, we have other macros that don't have normal C syntax, and
they are ugly too (example: #define CHKINFO(ret) in
drivers/video/fbdev/hgafb.c), but we should have higher standards for
globally visible helpers, and we should have *MUCH* higher standards
for helpers that are supposed to be all about reducing mistakes.

Bad / odd syntax does not reduce mistakes.

If a sane 'guard' model doesn't work for some code, the answer is not
to make an insane guard model. The answer is to not use 'guard' in
code like that.

               Linus