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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED 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 22FBBC46460 for ; Tue, 14 Aug 2018 13:51:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7B83E21700 for ; Tue, 14 Aug 2018 13:51:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gouders.net header.i=@gouders.net header.b="SE32+H4E" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7B83E21700 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gouders.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732822AbeHNQip (ORCPT ); Tue, 14 Aug 2018 12:38:45 -0400 Received: from services.gouders.net ([141.101.32.176]:44110 "EHLO services.gouders.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732667AbeHNQio (ORCPT ); Tue, 14 Aug 2018 12:38:44 -0400 Received: from localhost ([193.175.198.193]) (authenticated bits=0) by services.gouders.net (8.14.8/8.14.8) with ESMTP id w7EDidib027405 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 14 Aug 2018 15:44:40 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gouders.net; s=gnet; t=1534254280; bh=IGsFAP2AKkOYGxvfVWdieOc3ctXh0KqvO3uh6shWDJc=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=SE32+H4ERXxUDXuOVJhkXpqKoMnf/lj+ZJCJDchv5eBtUyxexantkCcfN9d4wl7IC RsCck4AcaBDy5D1Ral29PmmX64BKa7k2f/2Ao3YP/l+wa/W1T1WdqdRywIBYbFezzK 0qwu/AJd1NPBklU7Nyiu88Td0eFCh1/IwNgcRU0Q= From: Dirk Gouders To: Masahiro Yamada Cc: linux-kbuild@vger.kernel.org, Michal Marek , Sam Ravnborg , Ulf Magnusson , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] kconfig: report recursive dependency involving 'imply' In-Reply-To: (Dirk Gouders's message of "Tue, 14 Aug 2018 12:38:25 +0200") References: <1534229021-8056-1-git-send-email-yamada.masahiro@socionext.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.4 (gnu/linux) Date: Tue, 14 Aug 2018 15:44:39 +0200 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dirk Gouders writes: > Masahiro Yamada writes: > >> Currently, Kconfig does not report anything about the recursive >> dependency where 'imply' keywords are involved. >> >> [Test Code] >> >> config A >> bool "a" >> >> config B >> bool "b" >> imply A >> depends on A > > Hello Masahiro, > > obviously, it is hard to find a reason why one wants to use dependencies > like above but I also wonder how e.g. menuconfig handles this case: > > First, only "a" is visible, if I then select "a", "b" does not become > visible but when I then reset "a" to "n", "b" becomes visible. If I then > try to select "b", it becomes invisible... > > Perhaps it would be better to just error out instead of giving users the > impression, Kconfig thinks such questionable behavior is OK. > > Side note: perhaps, the documentation could be better when it comes to > recursive dependencies. The documentation says "select" and > "imply" can be used to specify lower limits whereas direct > dependencies specify upper limits for symbol values and with > this in mind, one might wonder why it is a problem to work > with both limits in a recursive way. > > Not very unlikely that it is just me who still has to > understand recursive dependencies or problems with reading > English text, though. > > What definitely seems to get void with your patches is item c) in > "Practical solutions to kconfig recursive issue" in > Documentation/kbuild/kconfig-language: > > c) Consider the use of "imply" instead of "select" Just some more information that adds to me feeling unsure about the correct definition of recursive dependencies: With commit 29c434f367ea (kconfig: tests: test if recursive dependencies are detected) a test case similar to the example above was introduced, explicitely stating it is _no_ recursive dependency: +# depends on and imply +# This is not recursive dependency + +config E1 + bool "E1" + depends on E2 + imply E2 + +config E2 + bool "E2" Dirk > >> In the code above, Kconfig cannot calculate the symbol values correctly >> due to the circular dependency. For example, allyesconfig followed by >> syncconfig results in an odd behavior because CONFIG_B becomes visible >> in syncconfig. >> >> $ make allyesconfig >> scripts/kconfig/conf --allyesconfig Kconfig >> # >> # configuration written to .config >> # >> $ cat .config >> # >> # Automatically generated file; DO NOT EDIT. >> # Main menu >> # >> CONFIG_A=y >> $ make syncconfig >> scripts/kconfig/conf --syncconfig Kconfig >> * >> * Restart config... >> * >> * >> * Main menu >> * >> a (A) [Y/n/?] y >> b (B) [N/y/?] (NEW) >> >> To report this correctly, sym_check_expr_deps() should recurse to >> not only sym->rev_dep.expr but also sym->implied.expr . >> >> At this moment, sym_check_print_recursive() cannot distinguish >> 'select' and 'imply' since it does not know the precise context >> where the recursive dependency is hit. This will be solved by >> the next commit. >> >> Signed-off-by: Masahiro Yamada >> --- >> >> scripts/kconfig/symbol.c | 9 +++++++-- >> 1 file changed, 7 insertions(+), 2 deletions(-) >> >> diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c >> index 4ec8b1f..7de7463a 100644 >> --- a/scripts/kconfig/symbol.c >> +++ b/scripts/kconfig/symbol.c >> @@ -1098,7 +1098,7 @@ static void sym_check_print_recursive(struct symbol *last_sym) >> sym->name ? sym->name : "", >> next_sym->name ? next_sym->name : ""); >> } else { >> - fprintf(stderr, "%s:%d:\tsymbol %s is selected by %s\n", >> + fprintf(stderr, "%s:%d:\tsymbol %s is selected or implied by %s\n", >> prop->file->name, prop->lineno, >> sym->name ? sym->name : "", >> next_sym->name ? next_sym->name : ""); >> @@ -1161,8 +1161,13 @@ static struct symbol *sym_check_sym_deps(struct symbol *sym) >> if (sym2) >> goto out; >> >> + sym2 = sym_check_expr_deps(sym->implied.expr); >> + if (sym2) >> + goto out; >> + >> for (prop = sym->prop; prop; prop = prop->next) { >> - if (prop->type == P_CHOICE || prop->type == P_SELECT) >> + if (prop->type == P_CHOICE || prop->type == P_SELECT || >> + prop->type == P_IMPLY) >> continue; >> stack.prop = prop; >> sym2 = sym_check_expr_deps(prop->visible.expr);