linux-kernel - Re: [PATCH 1/3] cleanup: Add cond

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Date: Tue, 27 Feb 2024 12:49:34 -0800
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Dan Williams <dan.j.williams@...el.com>
Cc: peterz@...radead.org, gregkh@...uxfoundation.org, 
	Dave Jiang <dave.jiang@...el.com>, Ira Weiny <ira.weiny@...el.com>, 
	Jonathan Cameron <Jonathan.Cameron@...wei.com>, 
	"Fabio M. De Francesco" <fabio.maria.de.francesco@...ux.intel.com>, linux-kernel@...r.kernel.org, 
	linux-cxl@...r.kernel.org
Subject: Re: [PATCH 1/3] cleanup: Add cond_guard() to conditional guards

On Tue, 27 Feb 2024 at 08:48, Dan Williams <dan.j.williams@...el.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