From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jani Nikula Subject: Re: [Intel-gfx] [PATCH] drm/i915: mark expected switch fall-through Date: Thu, 21 Jun 2018 11:03:14 +0300 Message-ID: <87r2l0va65.fsf@intel.com> References: <20180620133100.GA608@embeddedor.com> <20180620190628.GC8258@intel.com> <26740470-d7b7-0a58-0aae-fc628bd4f416@embeddedor.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <26740470-d7b7-0a58-0aae-fc628bd4f416@embeddedor.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: "Gustavo A. R. Silva" , Rodrigo Vivi Cc: David Airlie , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org T24gV2VkLCAyMCBKdW4gMjAxOCwgIkd1c3Rhdm8gQS4gUi4gU2lsdmEiIDxndXN0YXZvQGVtYmVk ZGVkb3IuY29tPiB3cm90ZToKPiBPbiAwNi8yMC8yMDE4IDAyOjA2IFBNLCBSb2RyaWdvIFZpdmkg d3JvdGU6Cj4+IE9uIFdlZCwgSnVuIDIwLCAyMDE4IGF0IDA4OjMxOjAwQU0gLTA1MDAsIEd1c3Rh dm8gQS4gUi4gU2lsdmEgd3JvdGU6Cj4+PiBJbiBwcmVwYXJhdGlvbiB0byBlbmFibGluZyAtV2lt cGxpY2l0LWZhbGx0aHJvdWdoLCBtYXJrIHN3aXRjaCBjYXNlcwo+Pj4gd2hlcmUgd2UgYXJlIGV4 cGVjdGluZyB0byBmYWxsIHRocm91Z2guCj4+Pgo+Pj4gQWRkcmVzc2VzLUNvdmVyaXR5LUlEOiAx NDcwMTAyICgiTWlzc2luZyBicmVhayBpbiBzd2l0Y2giKQo+PiAKPj4gQW55IG90aGVyIGFkdmFu dGFnZSBiZXNpZGVzIGNvdmVyaXR5Pwo+PiBDYW4ndCB3ZSBhZGRyZXNzIGl0IGJ5IG1hcmtpbmcg YXMgIkludGVudGlvbmFsIiBvbiB0aGUgdG9vbD8KPj4gCj4KPiBZZXMuIFRoZSBhZHZhbnRhZ2Ug b2YgdGhpcyBpcyB0aGF0IGl0IHdpbGwgZXZlbnR1YWxseSBhbGxvd3MgdG8gZW5hYmxlIAo+IC1X aW1wbGljaXQtZmFsbHRocm91Z2gsIGhlbmNlLCBlbmFibGluZyB0aGUgY29tcGlsZXIgdG8gdHJp Z2dlciBhIAo+IHdhcm5pbmcsIHdoaWNoIHdpbGwgZm9yY2UgdXMgdG8gZG91YmxlIGNoZWNrIGlm IHdlIGFyZSBhY3R1YWxseSBtaXNzaW5nIAo+IGEgYnJlYWsgYmVmb3JlIGNvbW1pdHRpbmcgdGhl IGNvZGUuCgpJIGFwcGxhdWQgdGhlIGVmZm9ydHMuIFNpbmNlIHlvdSdyZSBkb2luZyB0aGUgY29t bWVudCBjaGFuZ2VzLCBkbyB5b3UKaGF2ZSBhbiBpZGVhIHdoYXQgLVdpbXBsaWNpdC1mYWxsdGhy b3VnaD1OIGxldmVsIGlzIGJlaW5nIGNvbnNpZGVyZWQgZm9yCmtlcm5lbD8KCj4+IEknbSBhZnJh aWQgdGhlcmUgd2lsbCBiZSBzbyBtYW55IG1vcmUgcGxhY2VzIHRvIGFkZCBmYWxsdGhyb3VnaAo+ PiBtYXJrcy4uLi4KPj4gCj4KPiBPaCB5ZWFoLCB0aGVyZSBhcmUgYXJvdW5kIDEwMDAgc2ltaWxh ciBwbGFjZXMgaW4gdGhlIHdob2xlIGNvZGViYXNlLiAKPiBUaGVyZSBpcyBhbiBvbmdvaW5nIGVm Zm9ydCB0byByZXZpZXcgZWFjaCBjYXNlLiBNb250aHMgYWdvLCBpdCB1c2VkIHRvIAo+IGJlIGFy b3VuZCAxNTAwIG9mIHRoZXNlIGNhc2VzLgoKV2UgdXNlIG91ciBvd24gTUlTU0lOR19DQVNFKCkg dG8gaW5kaWNhdGUgc3R1ZmYgdGhhdCdzIG5vdCBzdXBwb3NlZCB0bwpoYXBwZW4sIG9yIHRvIGJl IGltcGxlbWVudGVkLCBldGMuIGFuZCBpbiBtYW55IGNhc2VzIHRoZSBmYWxsdGhyb3VnaCBpcwpu b3JtYWwuIEkgd29uZGVyIGlmIHdlIGNvdWxkIGVtYmVkIF9fYXR0cmlidXRlX18gKChmYWxsdGhy b3VnaCkpIGluCnRoZXJlIHRvIHRhY2tsZSBhbGwgb2YgdGhlc2Ugd2l0aG91dCBhIGNvbW1lbnQu CgpCUiwKSmFuaS4KCgotLSAKSmFuaSBOaWt1bGEsIEludGVsIE9wZW4gU291cmNlIEdyYXBoaWNz IENlbnRlcgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpk cmktZGV2ZWwgbWFpbGluZyBsaXN0CmRyaS1kZXZlbEBsaXN0cy5mcmVlZGVza3RvcC5vcmcKaHR0 cHM6Ly9saXN0cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9kcmktZGV2ZWwK From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6ADEC43140 for ; Thu, 21 Jun 2018 08:03:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8C0AA20883 for ; Thu, 21 Jun 2018 08:03:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8C0AA20883 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932620AbeFUIDa (ORCPT ); Thu, 21 Jun 2018 04:03:30 -0400 Received: from mga01.intel.com ([192.55.52.88]:61093 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932430AbeFUID0 (ORCPT ); Thu, 21 Jun 2018 04:03:26 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 21 Jun 2018 01:03:26 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,251,1526367600"; d="scan'208";a="65996855" Received: from jnikula-mobl2.fi.intel.com (HELO localhost) ([10.237.72.62]) by fmsmga001.fm.intel.com with ESMTP; 21 Jun 2018 01:03:24 -0700 From: Jani Nikula To: "Gustavo A. R. Silva" , Rodrigo Vivi Cc: Joonas Lahtinen , David Airlie , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [Intel-gfx] [PATCH] drm/i915: mark expected switch fall-through In-Reply-To: <26740470-d7b7-0a58-0aae-fc628bd4f416@embeddedor.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20180620133100.GA608@embeddedor.com> <20180620190628.GC8258@intel.com> <26740470-d7b7-0a58-0aae-fc628bd4f416@embeddedor.com> Date: Thu, 21 Jun 2018 11:03:14 +0300 Message-ID: <87r2l0va65.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 20 Jun 2018, "Gustavo A. R. Silva" wrote: > On 06/20/2018 02:06 PM, Rodrigo Vivi wrote: >> On Wed, Jun 20, 2018 at 08:31:00AM -0500, Gustavo A. R. Silva wrote: >>> In preparation to enabling -Wimplicit-fallthrough, mark switch cases >>> where we are expecting to fall through. >>> >>> Addresses-Coverity-ID: 1470102 ("Missing break in switch") >> >> Any other advantage besides coverity? >> Can't we address it by marking as "Intentional" on the tool? >> > > Yes. The advantage of this is that it will eventually allows to enable > -Wimplicit-fallthrough, hence, enabling the compiler to trigger a > warning, which will force us to double check if we are actually missing > a break before committing the code. I applaud the efforts. Since you're doing the comment changes, do you have an idea what -Wimplicit-fallthrough=N level is being considered for kernel? >> I'm afraid there will be so many more places to add fallthrough >> marks.... >> > > Oh yeah, there are around 1000 similar places in the whole codebase. > There is an ongoing effort to review each case. Months ago, it used to > be around 1500 of these cases. We use our own MISSING_CASE() to indicate stuff that's not supposed to happen, or to be implemented, etc. and in many cases the fallthrough is normal. I wonder if we could embed __attribute__ ((fallthrough)) in there to tackle all of these without a comment. BR, Jani. -- Jani Nikula, Intel Open Source Graphics Center