linux-kernel - Re: [PATCH v2 1/1] arm64: remove unnecessary ifdefs around is_compat

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Date: Tue,  9 Jan 2024 15:18:28 -0300
From: Leonardo Bras <leobras@...hat.com>
To: Arnd Bergmann <arnd@...db.de>
Cc: Leonardo Bras <leobras@...hat.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Kees Cook <keescook@...omium.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Mark Brown <broonie@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Guo Hui <guohui@...ontech.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/1] arm64: remove unnecessary ifdefs around is_compat_task()

On Tue, Jan 09, 2024 at 07:18:46AM +0100, Arnd Bergmann wrote:
> On Mon, Jan 8, 2024, at 18:43, Leonardo Bras wrote:
> > Currently some parts of the codebase will test for CONFIG_COMPAT before
> > testing is_compat_task().
> >
> > is_compat_task() is a inlined function only present on CONFIG_COMPAT.
> > On the other hand, for !CONFIG_COMPAT, we have in linux/compat.h:
> >
> >  #define is_compat_task() (0)
> >
> > Since we have this define available in every usage of is_compat_task() for
> > !CONFIG_COMPAT, it's unnecessary to keep the ifdefs, since the compiler is
> > smart enough to optimize-out those snippets on CONFIG_COMPAT=n
> >
> > This requires some regset code as well as a few other defines to be made
> > available on !CONFIG_COMPAT, so some symbols can get resolved before
> > getting optimized-out.
> >
> > Signed-off-by: Leonardo Bras <leobras@...hat.com>
> > ---
> > Changes since v1:
> > - Move some regset code and other defines outside of CONFIG_COMPAT
> > - Closes: 
> > https://lore.kernel.org/oe-kbuild-all/202401061219.Y2LD7LTx-lkp@intel.com/
> > Link: 
> > https://lore.kernel.org/all/20240105041458.126602-3-leobras@redhat.com/
> 
> Looks good to me, and did not cause any regressions in an overnight
> randconfig build loop.
> 
> Reviewed-by: Arnd Bergmann <arnd@...db.de>
> 

Thanks!
Leo