From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [GIT PULL] percpu fix for v4.10-rc6 Date: Tue, 31 Jan 2017 17:27:07 -0500 Message-ID: <20170131222707.GA5919@htj.duckdns.org> References: <20170131165537.GC23970@htj.duckdns.org> <20170131221141.GA5379@htj.duckdns.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pf0-f196.google.com ([209.85.192.196]:36839 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750830AbdAaW1P (ORCPT ); Tue, 31 Jan 2017 17:27:15 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Linus Torvalds Cc: "linux-arch@vger.kernel.org" , Linux Kernel Mailing List , dougmill@linux.vnet.ibm.com On Tue, Jan 31, 2017 at 02:17:10PM -0800, Linus Torvalds wrote: > Because there definitely have been users of the bitop routines that > assign the result to an "int", and I have some dim memory of us also > having had things like drivers that made their own "bool" variables > and use "char" for them. > > But I'm not seeing it. The generic bitop pattern seems to be > > static inline int test_and_change_bit(int nr, volatile unsigned long *addr) > ... > return (old & mask) != 0; > > which is fine. > > Just exactly what code did you look at? My bad. I misread the generic test_bit() code and was reading the inner helper of ppc, DEFINE_TESTOP macro, which returns the masked value. We used to have this problem, right? I seem to have a memory of hitting this issue. Is there a reason we don't make these functions explicitly return bool? To avoid unnecessary boolean conversion by the compiler? If so, there gotta be a way to avoid that. Thanks. -- tejun