linux-kernel - Re: [PATCH] HID: simplify code in fetch

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Message-ID: <Z_4ApoWzgWSovgRi@smile.fi.intel.com>
Date: Tue, 15 Apr 2025 09:45:58 +0300
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Nathan Chancellor <nathan@...nel.org>
Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jiri Kosina <jikos@...nel.org>,
	Benjamin Tissoires <bentiss@...nel.org>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev
Subject: Re: [PATCH] HID: simplify code in fetch_item()

On Mon, Apr 14, 2025 at 05:33:26PM -0700, Nathan Chancellor wrote:
> On Mon, Apr 14, 2025 at 09:30:36AM +0300, Andy Shevchenko wrote:
> > On Thu, Oct 10, 2024 at 03:24:51PM -0700, Nathan Chancellor wrote:
> > > On Tue, Oct 01, 2024 at 08:42:36AM -0700, Dmitry Torokhov wrote:

...

> > > Getting rid of the unreachable() in some way resolves the issue. I
> > > tested using BUG() in lieu of unreachable() like the second change I
> > > mentioned above, which resolves the issue cleanly, as the default case
> > > clearly cannot happen. ...
> > 
> > As Dmitry pointed out to this old discussion, I have a question about the above
> > test. Have you tried to use BUG() while CONFIG_BUG=n? Does it _also_ solve the
> > issue?
> 
> Yes because x86 appears to always emit ud2 for BUG() regardless of
> whether CONFIG_BUG is set or not since HAVE_ARCH_BUG is always
> respected.

Thank you for the reply. But do you know if this is guaranteed on the rest of
supported architectures? I.o.w. may we assume that BUG() in lieu of unreachable()
will always fix the issue?

-- 
With Best Regards,
Andy Shevchenko