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Tsirkin" To: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= Cc: Markus Armbruster , qemu-devel@nongnu.org, imp@bsdimp.com, kevans@freebsd.org, ben.widawsky@intel.com, jonathan.cameron@huawei.com, kbastian@mail.uni-paderborn.de, jasowang@redhat.com, michael.roth@amd.com, kkostiuk@redhat.com, tsimpson@quicinc.com, palmer@dabbelt.com, alistair.francis@wdc.com, bin.meng@windriver.com, qemu-riscv@nongnu.org, philmd@linaro.org, Bin Meng Subject: Re: [PATCH v3 1/1] include: Don't include qemu/osdep.h Message-ID: <20230112124707-mutt-send-email-mst@kernel.org> References: <20230112115005.1504812-1-armbru@redhat.com> <20230112115005.1504812-2-armbru@redhat.com> <20230112082537-mutt-send-email-mst@kernel.org> <20230112085520-mutt-send-email-mst@kernel.org> <87zgan4xoo.fsf@pond.sub.org> <20230112123434-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-riscv@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 Jan 2023 17:47:58 -0000 On Thu, Jan 12, 2023 at 05:44:31PM +0000, Daniel P. Berrangé wrote: > On Thu, Jan 12, 2023 at 12:37:46PM -0500, Michael S. Tsirkin wrote: > > On Thu, Jan 12, 2023 at 03:47:19PM +0100, Markus Armbruster wrote: > > > "Michael S. Tsirkin" writes: > > > > > > > On Thu, Jan 12, 2023 at 08:51:32AM -0500, Michael S. Tsirkin wrote: > > > >> On Thu, Jan 12, 2023 at 12:50:05PM +0100, Markus Armbruster wrote: > > > >> > docs/devel/style.rst mandates: > > > >> > > > > >> > The "qemu/osdep.h" header contains preprocessor macros that affect > > > >> > the behavior of core system headers like . It must be > > > >> > the first include so that core system headers included by external > > > >> > libraries get the preprocessor macros that QEMU depends on. > > > >> > > > > >> > Do not include "qemu/osdep.h" from header files since the .c file > > > >> > will have already included it. > > > >> > > > > >> > A few violations have crept in. Fix them. > > > >> > > > > >> > Signed-off-by: Markus Armbruster > > > >> > Reviewed-by: Philippe Mathieu-Daudé > > > >> > Reviewed-by: Bin Meng > > > >> > Reviewed-by: Taylor Simpson > > > >> > Reviewed-by: Alistair Francis > > > >> > > > >> With my awesome grep skillz I found one more: > > > >> $ grep -r --include='*.h' qemu/osdep.h > > > >> include/block/graph-lock.h:#include "qemu/osdep.h" > > > > > > Crept in after I prepared my v1. I neglected to re-check. > > > > > > > Also: > > > > $ grep -r --include='*.inc' qemu/osdep.h > > > > ui/vnc-enc-zrle.c.inc:#include "qemu/osdep.h" > > > > crypto/akcipher-nettle.c.inc:#include "qemu/osdep.h" > > > > crypto/akcipher-gcrypt.c.inc:#include "qemu/osdep.h" > > > > crypto/rsakey-nettle.c.inc:#include "qemu/osdep.h" > > > > crypto/cipher-gnutls.c.inc:#include "qemu/osdep.h" > > > > target/xtensa/core-dc233c/xtensa-modules.c.inc:#include "qemu/osdep.h" > > > > target/xtensa/core-sample_controller/xtensa-modules.c.inc:#include "qemu/osdep.h" > > > > target/xtensa/core-de212/xtensa-modules.c.inc:#include "qemu/osdep.h" > > > > target/xtensa/core-dc232b/xtensa-modules.c.inc:#include "qemu/osdep.h" > > > > target/xtensa/core-fsf/xtensa-modules.c.inc:#include "qemu/osdep.h" > > > > target/cris/translate_v10.c.inc:#include "qemu/osdep.h" > > > > > > Good point. Looks like I successfully supressed all memory of .inc. > > > > > > >> Looks like all C files must include qemu/osdep.h, no? > > > > > > I remember there are a few exceptions, but I don't remember which .c > > > they are. Hmm... see commit 4bd802b209cff612d1a99674a91895b735be8630. > > > > > > >> How about > > > >> > > > >> 1- add -include qemu/osdep.h on compile command line > > > >> drop #include "qemu/osdep.h" from C files > > > > > > Then you need to encode the exceptions in the build system. Which might > > > not be a bad thing. > > > > > > >> 2- drop double include guards, replace with a warning. > > > >> > > > >> following patch implements part 2: > > > >> > > > >> > > > >> qemu/osdep: don't include it from headers > > > >> > > > >> doing so will lead to trouble eventually - instead of > > > >> working around such cases make it more likely it will fail. > > > >> > > > >> Signed-off-by: Michael S. Tsirkin > > > >> > > > >> --- > > > >> > > > >> diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > > > >> index 7d059ad526..e4a60f911c 100644 > > > >> --- a/include/qemu/osdep.h > > > >> +++ b/include/qemu/osdep.h > > > >> @@ -24,7 +24,12 @@ > > > >> * This work is licensed under the terms of the GNU GPL, version 2 or later. > > > >> * See the COPYING file in the top-level directory. > > > >> */ > > > >> -#ifndef QEMU_OSDEP_H > > > >> +#ifdef QEMU_OSDEP_H > > > >> +#warning "Never include qemu/osdep.h from a header!" > > > >> +#endif > > > >> + > > > >> +static inline void qemu_osdep_never_include_from_header(void) {} > > > >> + > > > > > > Why do you need the function, too? > > > > This seems to give a bit more info if header does get included > > twice: instead of just a warning on the second include compiler says > > definition is duplicated and then shows where the first definition was. > > OTOH first one was almost for sure from the proper first include so > > maybe we don't care. Let me drop this. > > FWIW, if we want to simplify our header guards, we could replace the > > #ifndef FOO_H > #define FOO_H > > .... > > #endif /* FOO_H */ > > with merely > > #pragma once > > at the top of each header. > > With regards, > Daniel Will break this trick, won't it? -- MST