From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1754348AbdKQBGx (ORCPT <rfc822;w@1wt.eu>);
        Thu, 16 Nov 2017 20:06:53 -0500
Received: from mail-qt0-f194.google.com ([209.85.216.194]:44551 "EHLO
        mail-qt0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1754270AbdKQBGl (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 16 Nov 2017 20:06:41 -0500
X-Google-Smtp-Source: AGs4zMZWTlsNZewNw1LQqudZpSkQtU9tJ1ZRMJ54B7OU8z9TVkiZZ/3a60P2e890xF6JesZYz6a6oA==
Date: Thu, 16 Nov 2017 20:06:39 -0500 (EST)
From: Nicolas Pitre <nicolas.pitre@linaro.org>
To: Masahiro Yamada <yamada.masahiro@socionext.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Jan Beulich <JBeulich@suse.com>
cc: Arnd Bergmann <arnd@arndb.de>, linux-kbuild@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] kconfig: fix relational operators for bool and tristate
 symbols
Message-ID: <nycvar.YSQ.7.76.1711161956590.20817@knanqh.ubzr>
User-Agent: Alpine 2.21 (LFD 202 2017-01-01)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Since commit 31847b67bec0 ("kconfig: allow use of relations other than
(in)equality") it is possible to use relational operators in Kconfig
statements. However, those operators give unexpected results when
applied to bool/tristate values:

	(n < y) = y (correct)
	(m < y) = y (correct)
	(n < m) = n (wrong)

This happens because relational operators process bool and tristate
symbols as strings and m sorts before n. It makes little sense to do a
lexicographical compare on bool and tristate values though.

Documentation/kbuild/kconfig-language.txt states that expression can have
a value of 'n', 'm' or 'y' (or 0, 1, 2 respectively for calculations).
Let's make it so for relational comparisons with bool/tristate
expressions as well and document them. If at least one symbol is an
actual string then the lexicographical compare works just as before.

Signed-off-by: Nicolas Pitre <nico@linaro.org>

diff --git a/Documentation/kbuild/kconfig-language.txt b/Documentation/kbuild/kconfig-language.txt
index 262722d886..c4a293a03c 100644
--- a/Documentation/kbuild/kconfig-language.txt
+++ b/Documentation/kbuild/kconfig-language.txt
@@ -200,10 +200,14 @@ module state. Dependency expressions have the following syntax:
 <expr> ::= <symbol>                             (1)
            <symbol> '=' <symbol>                (2)
            <symbol> '!=' <symbol>               (3)
-           '(' <expr> ')'                       (4)
-           '!' <expr>                           (5)
-           <expr> '&&' <expr>                   (6)
-           <expr> '||' <expr>                   (7)
+           <symbol1> '<' <symbol2>              (4)
+           <symbol1> '>' <symbol2>              (4)
+           <symbol1> '<=' <symbol2>             (4)
+           <symbol1> '>=' <symbol2>             (4)
+           '(' <expr> ')'                       (5)
+           '!' <expr>                           (6)
+           <expr> '&&' <expr>                   (7)
+           <expr> '||' <expr>                   (8)
 
 Expressions are listed in decreasing order of precedence. 
 
@@ -214,10 +218,13 @@ Expressions are listed in decreasing order of precedence.
     otherwise 'n'.
 (3) If the values of both symbols are equal, it returns 'n',
     otherwise 'y'.
-(4) Returns the value of the expression. Used to override precedence.
-(5) Returns the result of (2-/expr/).
-(6) Returns the result of min(/expr/, /expr/).
-(7) Returns the result of max(/expr/, /expr/).
+(4) If value of <symbol1> is respectively lower, greater, lower-or-equal,
+    or greater-or-equal than value of <symbol2>, it returns 'y',
+    otherwise 'n'.
+(5) Returns the value of the expression. Used to override precedence.
+(6) Returns the result of (2-/expr/).
+(7) Returns the result of min(/expr/, /expr/).
+(8) Returns the result of max(/expr/, /expr/).
 
 An expression can have a value of 'n', 'm' or 'y' (or 0, 1, 2
 respectively for calculations). A menu entry becomes visible when its
diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
index cbf4996dd9..8cee597d33 100644
--- a/scripts/kconfig/expr.c
+++ b/scripts/kconfig/expr.c
@@ -893,7 +893,10 @@ static enum string_value_kind expr_parse_string(const char *str,
 	switch (type) {
 	case S_BOOLEAN:
 	case S_TRISTATE:
-		return k_string;
+		val->s = !strcmp(str, "n") ? 0 :
+			 !strcmp(str, "m") ? 1 :
+			 !strcmp(str, "y") ? 2 : -1;
+		return k_signed;
 	case S_INT:
 		val->s = strtoll(str, &tail, 10);
 		kind = k_signed;