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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 CE13EC4332B for ; Sat, 21 Mar 2020 15:10:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F0B320776 for ; Sat, 21 Mar 2020 15:10:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584803453; bh=U4Hf1hmpj4n70a3/9ZoGhX0jHOItFAm1K5F9LLLQG5Y=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=iELimPsIcVAAapJip4MYcQPaKQGF3v0vR6HVlFvY4WNXTbsICRUmR/XR99wDVOTc4 uQHxQ2wQu/s2VF8wEx+zzSX8v4d3/7MSsRRGqS+u2AujMLMhFGiMXYh0mAn2ooTQwJ sSlXxW7jf+qd8JTZVdOo7AVaYhRhv97EyFmIAvrg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727323AbgCUPKx (ORCPT ); Sat, 21 Mar 2020 11:10:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:49280 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727052AbgCUPKx (ORCPT ); Sat, 21 Mar 2020 11:10:53 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2E6AD20722; Sat, 21 Mar 2020 15:10:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584803452; bh=U4Hf1hmpj4n70a3/9ZoGhX0jHOItFAm1K5F9LLLQG5Y=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=AHeNcRU1kT/BqNbgah+oGx9/cwnhFBsv12DaB8F752VK/mbJkQzDvkQRAo/h0N33b +mwZOJC8veSw39sK5C3en+B4E2fGL/s8ZhAFNK20SWoWWDATbWVYGJ3YXvTwho0noE vy0Mljle2Tz1+OPfwfapthNvZdYMsYzrNmqyVqxc= Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=big-swifty.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jFfly-00EWFF-9R; Sat, 21 Mar 2020 15:10:50 +0000 Date: Sat, 21 Mar 2020 15:10:48 +0000 Message-ID: <86sgi1zqtj.wl-maz@kernel.org> From: Marc Zyngier To: "Gustavo A. R. Silva" Cc: Florian Fainelli , Thomas Gleixner , Jason Cooper , bcm-kernel-feedback-list@broadcom.com, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH][next] irqchip: irq-bcm7038-l1: Replace zero-length array with flexible-array member In-Reply-To: <20200319214438.GA21123@embeddedor.com> References: <20200319214438.GA21123@embeddedor.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 EasyPG/1.0.0 Emacs/26 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: gustavo@embeddedor.com, f.fainelli@gmail.com, tglx@linutronix.de, jason@lakedaemon.net, bcm-kernel-feedback-list@broadcom.com, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Thu, 19 Mar 2020 21:44:38 +0000, "Gustavo A. R. Silva" wrote: > > The current codebase makes use of the zero-length array language > extension to the C90 standard, but the preferred mechanism to declare > variable-length types such as these ones is a flexible array member[1][2], > introduced in C99: > > struct foo { > int stuff; > struct boo array[]; > }; > > By making use of the mechanism above, we will get a compiler warning > in case the flexible array does not occur last in the structure, which > will help us prevent some kind of undefined behavior bugs from being > inadvertently introduced[3] to the codebase from now on. > > Also, notice that, dynamic memory allocations won't be affected by > this change: > > "Flexible array members have incomplete type, and so the sizeof operator > may not be applied. As a quirk of the original implementation of > zero-length arrays, sizeof evaluates to zero."[1] > > This issue was found with the help of Coccinelle. > > [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html > [2] https://github.com/KSPP/linux/issues/21 > [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") > > Signed-off-by: Gustavo A. R. Silva > --- > drivers/irqchip/irq-bcm7038-l1.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Queued for 5.7. Thanks, M. -- Jazz is not dead, it just smells funny.