From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751919AbdJXJZU (ORCPT ); Tue, 24 Oct 2017 05:25:20 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:51652 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751372AbdJXJZQ (ORCPT ); Tue, 24 Oct 2017 05:25:16 -0400 X-Google-Smtp-Source: ABhQp+S6kw+r0y0iha4tO5kLN0P7ymYr6YOsZEkNVHGkQQr336GXgD0mQMNce/N/DQr/lQW0711qmQ== Date: Tue, 24 Oct 2017 11:25:12 +0200 From: Ingo Molnar To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, will.deacon@arm.com, mark.rutland@arm.com, snitzer@redhat.com, thor.thayer@linux.intel.com, viro@zeniv.linux.org.uk, davem@davemloft.net, shuah@kernel.org, mpe@ellerman.id.au, tj@kernel.org, torvalds@linux-foundation.org Subject: Re: [PATCH 16/19] linux/compiler.h: Split into compiler.h and compiler-types.h Message-ID: <20171024092512.nwumnxqrpaols55g@gmail.com> References: <20171023210408.GA2930@linux.vnet.ibm.com> <1508792849-3115-16-git-send-email-paulmck@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1508792849-3115-16-git-send-email-paulmck@linux.vnet.ibm.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Paul E. McKenney wrote: > From: Will Deacon > > linux/compiler.h is included indirectly by linux/types.h via > uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h > -> uapi/linux/stddef.h and is needed to provide a proper definition of > offsetof. > > Unfortunately, compiler.h requires a definition of > smp_read_barrier_depends() for defining lockless_dereference and soon > for defining READ_ONCE, which means that all > users of READ_ONCE will need to include asm/barrier.h to avoid splats > such as: > > In file included from include/uapi/linux/stddef.h:1:0, > from include/linux/stddef.h:4, > from arch/h8300/kernel/asm-offsets.c:11: > include/linux/list.h: In function 'list_empty': > >> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration] > smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ > ^ > > A better alternative is to include asm/barrier.h in linux/compiler.h, > but this requires a type definition for "bool" on some architectures > (e.g. x86), which is defined later by linux/types.h. Type "bool" is also > used directly in linux/compiler.h, so the whole thing is pretty fragile. > > This patch splits compiler.h in two: compiler-types.h contains type > annotations, definitions and the compiler-specific parts, whereas > compiler.h #includes compiler-types.h and additionally defines macros > such as {READ,WRITE.ACCESS}_ONCE. > > uapi/linux/stddef.h and linux/linkage.h are then moved over to include > linux/compiler-types.h, which fixes the build for h8 and blackfin. > > Reported-by: kbuild test robot > Signed-off-by: Will Deacon > Signed-off-by: Paul E. McKenney > [ paulmck: Add Will's fixes for issues reported by kbuild test robot. ] > --- > arch/arm/include/asm/ptrace.h | 3 +- > arch/sparc/include/asm/ptrace.h | 1 + > arch/um/include/shared/init.h | 2 +- > include/linux/compiler-clang.h | 2 +- > include/linux/compiler-gcc.h | 2 +- > include/linux/compiler-intel.h | 2 +- > include/linux/compiler-types.h | 274 ++++++++++++++++++++++++++++++++++++++++ > include/linux/compiler.h | 265 +------------------------------------- The common pattern is to use an underscore (compiler_types.h), not a hyphen (compiler-types.h) ... Even the patch description cites such an example, posix_types.h: > linux/compiler.h is included indirectly by linux/types.h via > uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h Thanks, Ingo