From patchwork Wed Feb 12 19:46:02 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 11379119 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D122C14E3 for ; Wed, 12 Feb 2020 20:07:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A58DE24650 for ; Wed, 12 Feb 2020 20:07:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=embeddedor.com header.i=@embeddedor.com header.b="wSKpavxf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727548AbgBLUHi (ORCPT ); Wed, 12 Feb 2020 15:07:38 -0500 Received: from gateway20.websitewelcome.com ([192.185.70.14]:29743 "EHLO gateway20.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727439AbgBLUHh (ORCPT ); Wed, 12 Feb 2020 15:07:37 -0500 X-Greylist: delayed 1448 seconds by postgrey-1.27 at vger.kernel.org; Wed, 12 Feb 2020 15:07:37 EST Received: from cm12.websitewelcome.com (cm12.websitewelcome.com [100.42.49.8]) by gateway20.websitewelcome.com (Postfix) with ESMTP id A8A9B400C647D for ; Wed, 12 Feb 2020 12:29:52 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 1xuzj1WJuvBMd1xuzj0B0F; Wed, 12 Feb 2020 13:43:29 -0600 X-Authority-Reason: nr=8 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=embeddedor.com; s=default; h=Content-Type:MIME-Version:Message-ID:Subject: Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=8FWXDkVW2wDjkeRVhdg2pGdPCjOZiCetHczI8jearAI=; b=wSKpavxf1MKDOkewMMDptIziQj DKEcF0hjxEfd0gk75Qp79sxH8dhY+hhDeWpcCIx9QAFYbqFP3+R7bFE+iVYGPE5y9Pwhw19A/7WhE wPYL/clnYeUdUCxyP/VgOMCW63JJulyeaEJUVyBYcyD8ZHMzXVFcvs00OyjQz5PUpnGAdfm5vE1SA mJ4ThVrzbKA0dEo3MwZsh2ma+OPwToVT3lxS683aHSHTZR4fWcpJ+H9vwCOXbQjD0M9LZHiQiCfk7 tkxXgukA5hR4/0ev8m4yQqJNm+YkBEUWeb9VpWiNkkkWdSMYtzl0EHwdxxx6UKc7p58e6P7HOJViY CCH6iSmQ==; Received: from [201.144.174.25] (port=23782 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j1xux-001DLa-VL; Wed, 12 Feb 2020 13:43:28 -0600 Date: Wed, 12 Feb 2020 13:46:02 -0600 From: "Gustavo A. R. Silva" To: Joshua Morris , Philip Kelleher , Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] rsxx: Replace zero-length array with flexible-array member Message-ID: <20200212194602.GA31712@embeddedor> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 201.144.174.25 X-Source-L: No X-Exim-ID: 1j1xux-001DLa-VL X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.144.174.25]:23782 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 40 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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 inadvertenly 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/block/rsxx/dma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/block/rsxx/dma.c b/drivers/block/rsxx/dma.c index 111eb659e66d..1914f5488b22 100644 --- a/drivers/block/rsxx/dma.c +++ b/drivers/block/rsxx/dma.c @@ -80,7 +80,7 @@ struct dma_tracker { struct dma_tracker_list { spinlock_t lock; int head; - struct dma_tracker list[0]; + struct dma_tracker list[]; };