linux-kernel - Re: [PATCH v2 2/5] i2c: designware: Optimize flag reading in i2c_dw

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aQyBs6H1IHk7fSP2@smile.fi.intel.com>
Date: Thu, 6 Nov 2025 13:08:35 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Benoît Monin <benoit.monin@...tlin.com>,
	Andi Shyti <andi.shyti@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Jan Dabros <jsd@...ihalf.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Clark Williams <clrkwllms@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	Gregory CLEMENT <gregory.clement@...tlin.com>,
	Théo Lebrun <theo.lebrun@...tlin.com>,
	Tawfik Bayouk <tawfik.bayouk@...ileye.com>,
	Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>,
	Dmitry Guzman <dmitry.guzman@...ileye.com>,
	linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-rt-devel@...ts.linux.dev
Subject: Re: [PATCH v2 2/5] i2c: designware: Optimize flag reading in
 i2c_dw_read()

On Thu, Nov 06, 2025 at 11:50:36AM +0100, Krzysztof Kozlowski wrote:
> On 31/10/2025 15:48, Andy Shevchenko wrote:
> > On Fri, Oct 31, 2025 at 03:35:40PM +0100, Benoît Monin wrote:
> >> Optimize the i2c_dw_read() function by reading the message flags only
> >> once per message, rather than for every byte.
> >>
> >> The message index is only modified by the outer loop, so reading the
> >> flags in the inner loop was always getting the same value.
> > 
> > Does it affect the binary (compiled) file?
> 
> It does not really matter that much, because new code is more readable -
> 'flags' depend on the outer (first) loop and they are used there, so
> that's where variable should be defined.

Did I oppose that?

-- 
With Best Regards,
Andy Shevchenko