Received: by 2002:a25:1506:0:0:0:0:0 with SMTP id 6csp402079ybv; Wed, 19 Feb 2020 01:54:30 -0800 (PST) X-Google-Smtp-Source: APXvYqzWWm8Fd8WnJ8B06gXrqrtCIP45JzsnV2wT6nT5uR0ig6FciBgJ0vteIFvAG23x5A83OPa6 X-Received: by 2002:a9d:6b06:: with SMTP id g6mr18971149otp.93.1582106070190; Wed, 19 Feb 2020 01:54:30 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1582106070; cv=none; d=google.com; s=arc-20160816; b=ktk0WHug7ysFeP3XddOiT4daM7akukAsP9ncni/qbb+dJAkesmuTzdDmS9cyLCpu3o v9wadT4LcXPcOFs3csFWUQJbM0KXX9wLfnMOdzdBrGi9nRFtrS10D8+toGzf3BOcrATf WbbPHlQcW7MMKfovMzIz+ibtuz1ooya9XDk4JYaX2rUvPHqXwUuaNPazXaSnPgED7S68 5IdNJKPxtZK+Dirfu3xD0P4HMSkzXKBRqkJXwcLHwgv1TAi5dG1etmNkfQpljqbl2JyZ nwmK/O5ouebgTpSzUH9lsD/+LicFwoiDHRu67poP2fqETpEmjaW0TzJVC2mqsk9o/48l KoEw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version; bh=+Bwu5MvltkUCeRO6er5fMDfuqToYZYnvunzcK/Xsz8w=; b=yX3zngyzFy2raphx1URZRnqvULQYcjPpqYXbppU0aRRIX6Yjb/cLgirQGMn8CDXe8M azDfLVlsz3q29FeOjBG3qCg7s9lJHVg4jYU+0gppSH0lZ9nue6Cm9ANxnU64aOz7jL0j dMQDbmyowwyseNNqC8dN7BTqsFqw+c3SlKJa2yp2rEK8Rvjhc72Po7E2nQYofpz+Vusk LUZ1VyZla7M4YUMQRsEx9L1DlHcjjE29Xb0fLm71kb5KYeAW+CJiFNh7VxrRM0vJzQZa L1j7ggGusTDdMHtE1b4noNbcfQbENG7lcl/rVl3eONGqpJe6RTgN5zwTKerNn6k/7juh oJxg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id n24si836986otf.58.2020.02.19.01.54.18; Wed, 19 Feb 2020 01:54:30 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726528AbgBSJyP (ORCPT + 99 others); Wed, 19 Feb 2020 04:54:15 -0500 Received: from mail-ot1-f66.google.com ([209.85.210.66]:40960 "EHLO mail-ot1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726385AbgBSJyO (ORCPT ); Wed, 19 Feb 2020 04:54:14 -0500 Received: by mail-ot1-f66.google.com with SMTP id r27so22501090otc.8; Wed, 19 Feb 2020 01:54:13 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=+Bwu5MvltkUCeRO6er5fMDfuqToYZYnvunzcK/Xsz8w=; b=GipGYnlpTXfmKu7qfmhDTY3idobdA8zsr75Pls5mhIOG2NgwC81J+DvqBpItncaLNf jaG0UrnWYRhlr5gW9gctnYEO1Q4XahLC7uMe2KOAZinYIiwaNkxECUkEJ1Btv3Zd5GYu 3KJLHblGdFqK9lxNwx9vGtVlvct1vOO2dWGMMmtXMr8wEAkJq+15jw96TWh8pK8kJCcW yOdBWAbQa4cVuoKoqlXq/y3KqssiWL9HUFAxv9KCJhpA/6A5QmdsQftg3HNqanXs+7jd uZuLoEsl7qQU5LQvcGp6s5D8rEFRtLA0oxnvDkz2Tz23yT/LcxdtxcF1b/gCR4RUSGxX 4p8A== X-Gm-Message-State: APjAAAXr1XuIvwT4w+9JUA+KFZwC0+ukMOIFLUf6RnyfsbsRbvuhSClT VZzlHPxztOU3mvmirHgOlvS7m6Y0YoymkaGQYWc= X-Received: by 2002:a9d:7602:: with SMTP id k2mr19153780otl.39.1582106053391; Wed, 19 Feb 2020 01:54:13 -0800 (PST) MIME-Version: 1.0 References: <20200219074950.23344-1-masahiroy@kernel.org> In-Reply-To: From: Geert Uytterhoeven Date: Wed, 19 Feb 2020 10:54:02 +0100 Message-ID: Subject: Re: [PATCH] kconfig: make 'imply' obey the direct dependency To: Masahiro Yamada Cc: linux-kbuild , Arnd Bergmann , Nicolas Pitre , Richard Cochran , Thomas Gleixner , John Stultz , Josh Triplett , Mark Brown , Ulf Magnusson , Jonathan Corbet , Michal Marek , "open list:DOCUMENTATION" , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Yamada-san, On Wed, Feb 19, 2020 at 10:24 AM Masahiro Yamada wrote: > On Wed, Feb 19, 2020 at 5:42 PM Geert Uytterhoeven wrote: > > On Wed, Feb 19, 2020 at 8:51 AM Masahiro Yamada wrote: > > > The 'imply' statement may create unmet direct dependency when the > > > implied symbol depends on m. > > > > > > [Test Code] > > > > > > config FOO > > > tristate "foo" > > > imply BAZ > > > > > > config BAZ > > > tristate "baz" > > > depends on BAR > > > > > > config BAR > > > def_tristate m > > > > > > config MODULES > > > def_bool y > > > option modules > > > > > > If you set FOO=y, BAZ is also promoted to y, which results in the > > > following .config file: > > > > > > CONFIG_FOO=y > > > CONFIG_BAZ=y > > > CONFIG_BAR=m > > > CONFIG_MODULES=y > > > > > > This ignores the dependency "BAZ depends on BAR". > > > > > > Unlike 'select', what is worse, Kconfig never shows the > > > "WARNING: unmet direct dependencies detected for ..." for this case. > > > > > > Because 'imply' should be weaker than 'depends on', Kconfig should > > > take the direct dependency into account. > > > > > > Describe this case in Documentation/kbuild/kconfig-language.rst for > > > clarification. > > > > > > Commit 237e3ad0f195 ("Kconfig: Introduce the "imply" keyword") says that > > > a symbol implied by y is restricted to y or n, excluding m. > > > > > > As for the combination of FOO=y and BAR=m, the case of BAZ=m is excluded > > > by the 'imply', and BAZ=y is also excluded by 'depends on'. So, only the > > > possible value is BAZ=n. > > > > > > Having said that, this case was probably "We don't care" at that time > > > because Kconfig did not handle 'depends on m' correctly until > > > commit f622f8279581 ("kconfig: warn unmet direct dependency of tristate > > > symbols selected by y") fixed it. > > > > > > Backporting this to 4.19+ will probably be fine. If you care this > > > problem on 4.14.x, you need to backport f622f8279581 as well. > > > > > > Signed-off-by: Masahiro Yamada > > > > Thanks a lot! This fixes the build issues in > > https://lore.kernel.org/alsa-devel/CAMuHMdW8SvDgQJyenTtEm4Xn2Ma6PK9pfwKR2_gn60t2AqNWXg@mail.gmail.com/ > > > > Tested-by: Geert Uytterhoeven > > Even if this patch fixes the build issues, > the result may not be what you expect. > > The very subtle part of 'imply' is that > symbols implied by 'y' cannot be 'm'. > > When CONFIG_SND_SOC_ALL_CODECS=y, > the select'ed drivers were previously able to be 'm'. > > After ea00d95200d02, drivers that were previously > 'm' are now 'n'. > > Probably, it shrunk the test-coverage. > > I'd recommend to compare the .config file. I always do, when running make oldconfig ;-) I only see expected changes from y to m. I don't see any unexpected changes from m to n. I do see a few unexpected "CONFIG_ is not set" that are no longer suppressed. --- .config.orig 2020-02-19 09:26:41.411812042 +0100 +++ .config 2020-02-19 09:28:05.143822097 +0100 @@ -1193,7 +1193,7 @@ CONFIG_REGMAP=y CONFIG_REGMAP_AC97=y CONFIG_REGMAP_I2C=y -CONFIG_REGMAP_SLIMBUS=y +CONFIG_REGMAP_SLIMBUS=m CONFIG_REGMAP_SPI=y CONFIG_REGMAP_MMIO=y CONFIG_REGMAP_IRQ=y @@ -5235,7 +5235,7 @@ CONFIG_SND_SOC_UDA1334=y CONFIG_SND_SOC_UDA134X=y CONFIG_SND_SOC_UDA1380=y CONFIG_SND_SOC_WCD934X=m CONFIG_SND_SOC_WL1273=y CONFIG_SND_SOC_WM0010=y @@ -5017,6 +5017,7 @@ CONFIG_SND_SOC_ARIZONA=y CONFIG_SND_SOC_WM_HUBS=y CONFIG_SND_SOC_WM_ADSP=y +# CONFIG_SND_SOC_AB8500_CODEC is not set CONFIG_SND_SOC_AC97_CODEC=y CONFIG_SND_SOC_AD1836=y CONFIG_SND_SOC_AD193X=y @@ -5085,6 +5086,7 @@ CONFIG_SND_SOC_CS4341=y CONFIG_SND_SOC_CS4349=y CONFIG_SND_SOC_CS47L15=y +# CONFIG_SND_SOC_CS47L24 is not set CONFIG_SND_SOC_CS47L35=y CONFIG_SND_SOC_CS47L85=y CONFIG_SND_SOC_CS47L90=y @@ -5117,6 +5119,7 @@ CONFIG_SND_SOC_INNO_RK3036=y CONFIG_SND_SOC_ISABELLE=y CONFIG_SND_SOC_LM49453=y +# CONFIG_SND_SOC_LOCHNAGAR_SC is not set CONFIG_SND_SOC_MADERA=y CONFIG_SND_SOC_MAX98088=y CONFIG_SND_SOC_MAX98090=y @@ -5228,11 +5231,12 @@ CONFIG_SND_SOC_TSCS42XX=y CONFIG_SND_SOC_TSCS454=y CONFIG_SND_SOC_TWL4030=y +# CONFIG_SND_SOC_TWL6040 is not set CONFIG_SND_SOC_UDA1334=y CONFIG_SND_SOC_UDA134X=y CONFIG_SND_SOC_UDA1380=y -CONFIG_SND_SOC_WCD9335=y -CONFIG_SND_SOC_WCD934X=y +CONFIG_SND_SOC_WCD9335=m +CONFIG_SND_SOC_WCD934X=m CONFIG_SND_SOC_WL1273=y CONFIG_SND_SOC_WM0010=y CONFIG_SND_SOC_WM1250_EV1=y @@ -5241,6 +5245,8 @@ CONFIG_SND_SOC_WM5100=y CONFIG_SND_SOC_WM5102=m CONFIG_SND_SOC_WM5110=y +# CONFIG_SND_SOC_WM8350 is not set +# CONFIG_SND_SOC_WM8400 is not set CONFIG_SND_SOC_WM8510=y CONFIG_SND_SOC_WM8523=y CONFIG_SND_SOC_WM8524=y @@ -5293,7 +5299,7 @@ CONFIG_SND_SOC_MAX9768=y CONFIG_SND_SOC_MAX9877=y # CONFIG_SND_SOC_DUMMY is not set -CONFIG_SND_SOC_MC13783=y +CONFIG_SND_SOC_MC13783=m CONFIG_SND_SOC_ML26124=y CONFIG_SND_SOC_MT6351=y CONFIG_SND_SOC_MT6358=y @@ -5899,6 +5905,7 @@ # CONFIG_COMMON_CLK_MT8516 is not set # end of Clock driver for MediaTek SoC +# CONFIG_COMMON_CLK_AXG_AUDIO is not set CONFIG_QCOM_GDSC=y CONFIG_COMMON_CLK_QCOM=m CONFIG_QCOM_A53PLL=m Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds