From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753891AbcHRL3o (ORCPT ); Thu, 18 Aug 2016 07:29:44 -0400 Received: from s3.sipsolutions.net ([5.9.151.49]:50084 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753627AbcHRL3m (ORCPT ); Thu, 18 Aug 2016 07:29:42 -0400 From: Johannes Berg To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Jens Axboe , Johannes Berg Subject: [PATCH] min/max: remove sparse warnings when they're nested Date: Thu, 18 Aug 2016 13:29:33 +0200 Message-Id: <1471519773-29882-1-git-send-email-johannes@sipsolutions.net> X-Mailer: git-send-email 2.8.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Johannes Berg Currently, when min/max are nested within themselves, sparse will warn: warning: symbol '_min1' shadows an earlier one originally declared here warning: symbol '_min1' shadows an earlier one originally declared here warning: symbol '_min2' shadows an earlier one originally declared here This also immediately happens when min3() or max3() are used. Since sparse implements __COUNTER__, we can use __UNIQUE_ID() to generate unique variable names, avoiding this. Signed-off-by: Johannes Berg --- So I'm on a bit of a quest to quell useless sparse warnings. Maybe this is over the top... it does seem to work though :) --- include/linux/kernel.h | 48 ++++++++++++++++++++++++++++-------------------- 1 file changed, 28 insertions(+), 20 deletions(-) diff --git a/include/linux/kernel.h b/include/linux/kernel.h index d96a6118d26a..853c4bf027ea 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -736,17 +736,25 @@ static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { } * strict type-checking.. See the * "unnecessary" pointer comparison. */ -#define min(x, y) ({ \ - typeof(x) _min1 = (x); \ - typeof(y) _min2 = (y); \ - (void) (&_min1 == &_min2); \ - _min1 < _min2 ? _min1 : _min2; }) - -#define max(x, y) ({ \ - typeof(x) _max1 = (x); \ - typeof(y) _max2 = (y); \ - (void) (&_max1 == &_max2); \ - _max1 > _max2 ? _max1 : _max2; }) +#define __min(t1, t2, min1, min2, x, y) ({ \ + t1 min1 = (x); \ + t2 min2 = (y); \ + (void) (&min1 == &min2); \ + min1 < min2 ? min1 : min2; }) +#define min(x, y) \ + __min(typeof(x), typeof(y), \ + __UNIQUE_ID(min1_), __UNIQUE_ID(min2_), \ + x, y) + +#define __max(t1, t2, max1, max2, x, y) ({ \ + t1 max1 = (x); \ + t2 max2 = (y); \ + (void) (&max1 == &max2); \ + max1 > max2 ? max1 : max2; }) +#define max(x, y) \ + __max(typeof(x), typeof(y), \ + __UNIQUE_ID(max1_), __UNIQUE_ID(max2_), \ + x, y) #define min3(x, y, z) min((typeof(x))min(x, y), z) #define max3(x, y, z) max((typeof(x))max(x, y), z) @@ -778,15 +786,15 @@ static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { } * * Or not use min/max/clamp at all, of course. */ -#define min_t(type, x, y) ({ \ - type __min1 = (x); \ - type __min2 = (y); \ - __min1 < __min2 ? __min1: __min2; }) - -#define max_t(type, x, y) ({ \ - type __max1 = (x); \ - type __max2 = (y); \ - __max1 > __max2 ? __max1: __max2; }) +#define min_t(type, x, y) \ + __min(type, type, \ + __UNIQUE_ID(min1_), __UNIQUE_ID(min2_), \ + x, y) + +#define max_t(type, x, y) \ + __max(type, type, \ + __UNIQUE_ID(min1_), __UNIQUE_ID(min2_), \ + x, y) /** * clamp_t - return a value clamped to a given range using a given type -- 2.8.1