Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932574Ab1DLVLS (ORCPT ); Tue, 12 Apr 2011 17:11:18 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:50160 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932155Ab1DLVLR (ORCPT ); Tue, 12 Apr 2011 17:11:17 -0400 Date: Tue, 12 Apr 2011 14:10:40 -0700 From: Andrew Morton To: Randy Dunlap Cc: Alexey Dobriyan , linux-kernel@vger.kernel.org, behlendorf1@llnl.gov, oleg@redhat.com Subject: Re: [PATCH] remove abs64() Message-Id: <20110412141040.a5706346.akpm@linux-foundation.org> In-Reply-To: <20110412140726.3f4f2a7b.rdunlap@xenotime.net> References: <20110412210045.GA19901@p183> <20110412140726.3f4f2a7b.rdunlap@xenotime.net> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2161 Lines: 63 On Tue, 12 Apr 2011 14:07:26 -0700 Randy Dunlap wrote: > > --- a/include/linux/kernel.h > > +++ b/include/linux/kernel.h > > @@ -143,28 +143,27 @@ extern int _cond_resched(void); > > > > #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0) > > > > -/* > > - * abs() handles unsigned and signed longs, ints, shorts and chars. For all > > - * input types abs() returns a signed long. > > - * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64() > > - * for those. > > - */ > > -#define abs(x) ({ \ > > - long ret; \ > > - if (sizeof(x) == sizeof(long)) { \ > > - long __x = (x); \ > > - ret = (__x < 0) ? -__x : __x; \ > > - } else { \ > > - int __x = (x); \ > > - ret = (__x < 0) ? -__x : __x; \ > > - } \ > > - ret; \ > > - }) > > - > > -#define abs64(x) ({ \ > > - s64 __x = (x); \ > > - (__x < 0) ? -__x : __x; \ > > - }) > > +#define abs(x) \ > > +({ \ > > + typeof(x) _x = (x); \ > > + \ > > + __builtin_choose_expr( \ > > + __builtin_types_compatible_p(typeof(_x), signed char), \ > > + (unsigned char)({ _x < 0 ? -_x : _x; }), \ > > + __builtin_choose_expr( \ > > + __builtin_types_compatible_p(typeof(_x), short), \ > > + (unsigned short)({ _x < 0 ? -_x : _x; }), \ > > + __builtin_choose_expr( \ > > + __builtin_types_compatible_p(typeof(_x), int), \ > > + (unsigned int)({ _x < 0 ? -_x : _x; }), \ > > + __builtin_choose_expr( \ > > + __builtin_types_compatible_p(typeof(_x), long), \ > > + (unsigned long)({ _x < 0 ? -_x : _x; }), \ > > + __builtin_choose_expr( \ > > + __builtin_types_compatible_p(typeof(_x), long long), \ > > + (unsigned long long)({ _x < 0 ? -_x : _x; }), \ > > + _x))))); \ > > +}) > > that is better? I think so. It's a bit concerning that it changes the return type of abs(). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/