From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753490AbdL1M3h (ORCPT ); Thu, 28 Dec 2017 07:29:37 -0500 Received: from mail-wr0-f195.google.com ([209.85.128.195]:43940 "EHLO mail-wr0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753343AbdL1M3f (ORCPT ); Thu, 28 Dec 2017 07:29:35 -0500 X-Google-Smtp-Source: ACJfBovIaTyZie6PrM6u0Imb78zuLy85OQm8d2eRw3DpEqeYUHSQ8aWruqmrcEx9XsRh8j/P3cRScw== Date: Thu, 28 Dec 2017 13:29:31 +0100 From: Ingo Molnar To: Julia Lawall Cc: Andy Shevchenko , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Andi Kleen , linux-kernel@vger.kernel.org, Darren Hart , platform-driver-x86@vger.kernel.org, Bhumika Goyal Subject: Re: [PATCH v1] x86/platform/intel-mid: Revert "Make 'bt_sfi_data' const" Message-ID: <20171228122931.ie5dggc43g6zjkkc@gmail.com> References: <20171228100801.67744-1-andriy.shevchenko@linux.intel.com> <20171228102812.cm7yylrrq2omfw5y@gmail.com> <1514463164.7000.328.camel@linux.intel.com> <20171228121711.xwydozmtj5jhwkgj@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Julia Lawall wrote: > > > On Thu, 28 Dec 2017, Ingo Molnar wrote: > > > > > * Andy Shevchenko wrote: > > > > > On Thu, 2017-12-28 at 11:28 +0100, Ingo Molnar wrote: > > > > * Andy Shevchenko wrote: > > > > > > > > > The annoying static analyzer follow up patches make a pain rather > > > > > then > > > > > fixing issues. > > > > > > > > > > The one done by commit 276c87054751 > > > > > > > > > > ("x86/platform/intel-mid: Make 'bt_sfi_data' const") > > > > > > > > > > made an obvious regression [BugLink] since the struct bt_sfi_data > > > > > used > > > > > as a temporary container for important data that is used to fill > > > > > 'parent' and 'name' fields in struct platform_device_info. > > > > > > > > > > That's why revert the commit which had been apparently done w/o > > > > > reading > > > > > the code. > > > > > > > > > > BugLink: https://github.com/andy-shev/linux/issues/20 > > > > > Cc: Bhumika Goyal > > > > > Cc: julia.lawall@lip6.fr > > > > > Signed-off-by: Andy Shevchenko > > > > > --- > > > > > arch/x86/platform/intel-mid/device_libs/platform_bt.c | 2 +- > > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > > > diff --git a/arch/x86/platform/intel-mid/device_libs/platform_bt.c > > > > > b/arch/x86/platform/intel-mid/device_libs/platform_bt.c > > > > > index dc036e511f48..5a0483e7bf66 100644 > > > > > --- a/arch/x86/platform/intel-mid/device_libs/platform_bt.c > > > > > +++ b/arch/x86/platform/intel-mid/device_libs/platform_bt.c > > > > > @@ -60,7 +60,7 @@ static int __init tng_bt_sfi_setup(struct > > > > > bt_sfi_data *ddata) > > > > > return 0; > > > > > } > > > > > > > > > > -static const struct bt_sfi_data tng_bt_sfi_data __initdata = { > > > > > +static struct bt_sfi_data tng_bt_sfi_data __initdata = { > > > > > .setup = tng_bt_sfi_setup, > > > > > }; > > > > > > > > This is nasty, why didn't the compiler warn about this bug? > > > > > > > > Normally when using a const data structure for a non-const purpose. > > > > (Unless > > > > there's a type cast which loses the type - one of the many reasons why > > > > type casts > > > > should be avoided.) > > > > > > Now I'm trying to get this. > > > > > > First of all, the new dependency to hci_bcm makes this one not compiled > > > at all. > > > > > > Second, there is a cast as you truthfully predicted... > > > > > > I would say that revert is needed, but it seems it wasn't a culprit for > > > the bug (rather the new dependency is). So, it might need rewording of > > > the commit message to low tone of the accusations. > > > > Your fix is absolutely needed and welcome, but I'd first like to see a build error > > or build warning that avoids the introduction of this class of problems in the > > future - then apply your fix in a separate patch. > > > > Constification patches are useful in general, and such breakages are hard to debug > > I will try to make the type adjustment. Assuming it's all a natural improvement to the affected code. I'm really just guessing blindly here - reality might interfere! > [...] There does seem to be a few cases where the field actually does hold an > integer. I guess this is not a problem? Could you point to such an example? Thanks, Ingo