From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CF6CFC433DF for ; Sun, 7 Jun 2020 03:22:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AC35D2076D for ; Sun, 7 Jun 2020 03:22:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591500126; bh=ouJh7ctrFQIX2AaifD+Bpxmo4jwPHs0v28YTqMiM5Bg=; h=From:To:Cc:Subject:Date:List-ID:From; b=t6W6sFkV/1YvJHJO9TyH7goXRdXnBRO1ndsdj2vJOTsf1Yfh928YpUr6PisY5iDeu ySmxjSysIBd1bauuoTF/FyVlKwegDAK7FELxKNQi5afhpCFjciBDBqVkBL1/cQsCDj uZEAPO/kL5HJPK7xtNbEAiN5H0szdzAV4xD/GVYY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726290AbgFGDWG (ORCPT ); Sat, 6 Jun 2020 23:22:06 -0400 Received: from conuserg-07.nifty.com ([210.131.2.74]:32272 "EHLO conuserg-07.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726068AbgFGDWF (ORCPT ); Sat, 6 Jun 2020 23:22:05 -0400 Received: from oscar.flets-west.jp (softbank126090202047.bbtec.net [126.90.202.47]) (authenticated) by conuserg-07.nifty.com with ESMTP id 0573L2JF032694; Sun, 7 Jun 2020 12:21:03 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-07.nifty.com 0573L2JF032694 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1591500063; bh=RZSBo4uUs11Af4WbcUObWOlCtSGazVl7ad8S22WoF3c=; h=From:To:Cc:Subject:Date:From; b=KgYKiWqgQ/g7oz7cNrX5ZywlcaqUaJecOmaqHEU1+3uCRn/mw+BlNrLV0NfmzFrKz en0WhehQQfS4oHg+4gMyZ91YMyLesEqbNZ5fwqOha8PFVM2LOtqsOZ8ejPsRnNGv8B umXrYMvFZJgh4140UqrRZd3W/xxLnPOkxD+b0i4U2ZioM34GOgUBPcs2kzX8xgbGpl SMpvlenaNJvd984HWiJYB5vI+mnx0Ec9vh6i9NMWfjdmFuC0drL2kn0tkVvHhrKuWS eAH+52B/ggBI1qRSdDBgPJlzS8oRN3IJTq6lDmvzbKH3xYG5+S9P5p11fFWEaCu7vi ODOjVs4MSWx4w== X-Nifty-SrcIP: [126.90.202.47] From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: Arnd Bergmann , Christian Brauner , Masahiro Yamada , Christian Brauner , Jonathan Corbet , linux-kernel@vger.kernel.org Subject: [PATCH] samples: binderfs: really compile this sample and fix build issues Date: Sun, 7 Jun 2020 12:20:53 +0900 Message-Id: <20200607032053.145302-1-masahiroy@kernel.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Even after commit c624adc9cb6e ("samples: fix binderfs sample"), this sample is never compiled. 'hostprogs' teaches Kbuild that this is a host program, but not enough to order to compile it. You must add it to 'always-y' to really compile it. Since this sample has never been compiled in upstream, various issues are left unnoticed. [1] compilers without are still widely used is only available since commit c13295ad219d ("binderfs: rename header to binderfs.h"), i.e., Linux 5.0 If your compiler is based on UAPI headers older than Linux 5.0, you will see the following error: samples/binderfs/binderfs_example.c:16:10: fatal error: linux/android/binderfs.h: No such file or directory #include ^~~~~~~~~~~~~~~~~~~~~~~~~~ compilation terminated. You cannot rely on compilers to have such a new header. The common approach is to install UAPI headers of this kernel into usr/include, and then add it to the header include path. I added 'depends on HEADERS_INSTALL' in Kconfig, and '-I usr/include' compiler flag in Makefile. [2] compile the sample for target architecture Since headers_install works for the target architecture, only the native build was able to build sample code that requires '-I usr/include'. Commit 7f3a59db274c ("kbuild: add infrastructure to build userspace programs") added the new syntax 'userprogs' to compile user-space programs for the target architecture. Use it, and 'ifndef CROSS_COMPILE' will go away. I added 'depends on CC_CAN_LINK' because $(CC) is not necessarily capable of linking user-space programs. [3] use subdir-y to descend into samples/binderfs/ Since this directory does not contain any kernel-space code, it has no point to generate built-in.a or modules.order. Replace obj-$(CONFIG_...) with subdir-$(CONFIG_...). [4] -Wunused-variable warning If I compile this, I see the following warning. samples/binderfs/binderfs_example.c: In function 'main': samples/binderfs/binderfs_example.c:21:9: warning: unused variable 'len' [-Wunused-variable] 21 | size_t len; | ^~~ I removed the unused 'len'. [5] CONFIG_ANDROID_BINDERFS is not required Since this is a user-space standalone program, it is independent of the kernel configuration. Remove 'depends on ANDROID_BINDERFS'. Fixes: 9762dc1432e1 ("samples: add binderfs sample program") Fixes: c624adc9cb6e ("samples: fix binderfs sample") Signed-off-by: Masahiro Yamada --- samples/Kconfig | 2 +- samples/Makefile | 2 +- samples/binderfs/Makefile | 9 ++++----- samples/binderfs/binderfs_example.c | 1 - 4 files changed, 6 insertions(+), 8 deletions(-) diff --git a/samples/Kconfig b/samples/Kconfig index 0cbb6146f3cf..953abbdebf7b 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -185,7 +185,7 @@ config SAMPLE_VFIO_MDEV_MBOCHS config SAMPLE_ANDROID_BINDERFS bool "Build Android binderfs example" - depends on ANDROID_BINDERFS + depends on CC_CAN_LINK && HEADERS_INSTALL help Builds a sample program to illustrate the use of the Android binderfs filesystem. diff --git a/samples/Makefile b/samples/Makefile index 29c66aadd954..4029d207cebb 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -2,7 +2,7 @@ # Makefile for Linux samples code subdir-$(CONFIG_SAMPLE_AUXDISPLAY) += auxdisplay -obj-$(CONFIG_SAMPLE_ANDROID_BINDERFS) += binderfs/ +subdir-$(CONFIG_SAMPLE_ANDROID_BINDERFS) += binderfs obj-$(CONFIG_SAMPLE_CONFIGFS) += configfs/ obj-$(CONFIG_SAMPLE_CONNECTOR) += connector/ subdir-$(CONFIG_SAMPLE_HIDRAW) += hidraw diff --git a/samples/binderfs/Makefile b/samples/binderfs/Makefile index a3ac5476338a..989e4badaee2 100644 --- a/samples/binderfs/Makefile +++ b/samples/binderfs/Makefile @@ -1,6 +1,5 @@ # SPDX-License-Identifier: GPL-2.0-only -ifndef CROSS_COMPILE -ifdef CONFIG_SAMPLE_ANDROID_BINDERFS -hostprogs := binderfs_example -endif -endif +userprogs := binderfs_example +always-y := $(userprogs) + +userccflags += -I usr/include diff --git a/samples/binderfs/binderfs_example.c b/samples/binderfs/binderfs_example.c index 5bbd2ebc0aea..0fd92cdda460 100644 --- a/samples/binderfs/binderfs_example.c +++ b/samples/binderfs/binderfs_example.c @@ -18,7 +18,6 @@ int main(int argc, char *argv[]) { int fd, ret, saved_errno; - size_t len; struct binderfs_device device = { 0 }; ret = unshare(CLONE_NEWNS); -- 2.25.1