Re: [PATCH 31/33] powerpc/64: make buildable without CONFIG_COMPAT

From: Arnd Bergmann <arnd@arndb.de>
To: "Michal Suchánek" <msuchanek@suse.de>
Cc: Nicholas Piggin <npiggin@gmail.com>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Allison Randal <allison@lohutok.net>,
	Andrew Donnellan <andrew.donnellan@au1.ibm.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Brajeswar Ghosh <brajeswar.linux@gmail.com>,
	Claudio Carvalho <cclaudio@linux.ibm.com>,
	Christian Brauner <christian@brauner.io>,
	Christophe Leroy <christophe.leroy@c-s.fr>,
	David Hildenbrand <david@redhat.com>,
	David Howells <dhowells@redhat.com>,
	Diana Craciun <diana.craciun@nxp.com>,
	Daniel Axtens <dja@axtens.net>,
	Dmitry Vyukov <dvyukov@google.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Firoz Khan <firoz.khan@linaro.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Gustavo Romero <gromero@linux.ibm.com>,
	Hari Bathini <hbathini@linux.ibm.com>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	Jagadeesh Pagadala <jagdsh.linux@gmail.com>,
	Breno Leitao <leitao@debian.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Madhavan Srinivasan <maddy@linux.vnet.ibm.com>,
	Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>,
	Mathieu Malaterre <malat@debian.org>,
	Michael Neuling <mikey@neuling.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
	Nicolai Stange <nstange@suse.de>, Oleg Nesterov <oleg@redhat.com>,
	Paul Mackerras <paulus@samba.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Russell Currey <ruscur@russell.cc>,
	Thomas Gleixner <tglx@linutronix.de>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Masahiro Yamada <yamada.masahiro@socionext.com>
Subject: Re: [PATCH 31/33] powerpc/64: make buildable without CONFIG_COMPAT
Date: Wed, 13 Nov 2019 11:04:03 +0100	[thread overview]
Message-ID: <CAK8P3a0ikEMP6MQzL8QPMTgdA-euf7_AsFZAbxkDbFh=smMuaQ@mail.gmail.com> (raw)
In-Reply-To: <20191113084137.GI2770@kitsune.suse.cz>

On Wed, Nov 13, 2019 at 9:41 AM Michal Suchánek <msuchanek@suse.de> wrote:
>
> On Wed, Nov 13, 2019 at 01:02:34PM +1000, Nicholas Piggin wrote:

> > >
> > > @@ -277,7 +276,7 @@ static void do_signal(struct task_struct *tsk)
> > >
> > >     rseq_signal_deliver(&ksig, tsk->thread.regs);
> > >
> > > -   if (is32) {
> > > +   if (is_32bit_task()) {
> > >             if (ksig.ka.sa.sa_flags & SA_SIGINFO)
> > >                     ret = handle_rt_signal32(&ksig, oldset, tsk);
> > >             else
> >
> > This is just a clean up I guess.
>
> It also expands directly to if(0) or if(1) for the !COMPAT cases. I am
> not sure how it would work with the intermediate variable.
>
> There was more complex change initially but after some additional
> cleanups removing the variable is the only part left.

I would be surprised if that made any difference to a modern compiler,
but the new version is definitely clearer to human readers.

       Arnd