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=-13.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 F37EAC3F2D1 for ; Tue, 3 Mar 2020 02:01:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AC71D2465E for ; Tue, 3 Mar 2020 02:01:50 +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="TG3dcPlh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726946AbgCCCBt (ORCPT ); Mon, 2 Mar 2020 21:01:49 -0500 Received: from gateway30.websitewelcome.com ([192.185.179.30]:35206 "EHLO gateway30.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726773AbgCCCBt (ORCPT ); Mon, 2 Mar 2020 21:01:49 -0500 Received: from cm13.websitewelcome.com (cm13.websitewelcome.com [100.42.49.6]) by gateway30.websitewelcome.com (Postfix) with ESMTP id 6D11418B94 for ; Mon, 2 Mar 2020 20:01:47 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 8wsVjlBTuRP4z8wsVj8wOe; Mon, 02 Mar 2020 20:01:47 -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-Transfer-Encoding:Content-Type: In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=bJM0vW/jtRTxwCbz2zQ/yV7VRsUN7y2H/RPdljAId+g=; b=TG3dcPlhoN/1PUVLWQrp0t7XkB bfGmGf5DdTsQ1VUZf3qg0qMzuofI/gWLd3PSQBToxdZhTjheml0F/WhtKfHjxcATl9usIlr4KWqfr 4ii8s3rGBwSmOUkOxWty9YwtdZoZFn31jocj1OFpzJ0r26GZY8rQwHFfFXWRs0wkgC4X3azXVbOId poHV5fSoUsLwTX5C4C+6uWs/GzfAkWw7a0wXlIu2S5cjhQflHvEnaxFYtgMhUTk+diAhNXSWu10hJ 4QpEk1/JKgGVOMRB7fNqQLLkbXs6r0gb45aXO2k5cdf72EX3R58w8N0XnvKKVwvydDkjmAq8i4IvQ 8BTZzICA==; Received: from [201.162.167.16] (port=17582 helo=[192.168.43.132]) by gator4166.hostgator.com with esmtpsa (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.92) (envelope-from ) id 1j8wsU-002Nhr-UO; Mon, 02 Mar 2020 20:01:47 -0600 Subject: Re: [PATCH] ocfs2: Replace zero-length array with flexible-array member To: Joseph Qi , Mark Fasheh , Joel Becker , Andrew Morton Cc: ocfs2-devel@oss.oracle.com, linux-kernel@vger.kernel.org References: <20200213160244.GA6088@embeddedor> <1b78acd5-2b5f-55f1-5571-73f45d3c87f7@embeddedor.com> <30493b5f-752d-147f-3d64-95b1c59895ae@linux.alibaba.com> From: "Gustavo A. R. Silva" Autocrypt: addr=gustavo@embeddedor.com; keydata= xsFNBFssHAwBEADIy3ZoPq3z5UpsUknd2v+IQud4TMJnJLTeXgTf4biSDSrXn73JQgsISBwG 2Pm4wnOyEgYUyJd5tRWcIbsURAgei918mck3tugT7AQiTUN3/5aAzqe/4ApDUC+uWNkpNnSV tjOx1hBpla0ifywy4bvFobwSh5/I3qohxDx+c1obd8Bp/B/iaOtnq0inli/8rlvKO9hp6Z4e DXL3PlD0QsLSc27AkwzLEc/D3ZaqBq7ItvT9Pyg0z3Q+2dtLF00f9+663HVC2EUgP25J3xDd 496SIeYDTkEgbJ7WYR0HYm9uirSET3lDqOVh1xPqoy+U9zTtuA9NQHVGk+hPcoazSqEtLGBk YE2mm2wzX5q2uoyptseSNceJ+HE9L+z1KlWW63HhddgtRGhbP8pj42bKaUSrrfDUsicfeJf6 m1iJRu0SXYVlMruGUB1PvZQ3O7TsVfAGCv85pFipdgk8KQnlRFkYhUjLft0u7CL1rDGZWDDr NaNj54q2CX9zuSxBn9XDXvGKyzKEZ4NY1Jfw+TAMPCp4buawuOsjONi2X0DfivFY+ZsjAIcx qQMglPtKk/wBs7q2lvJ+pHpgvLhLZyGqzAvKM1sVtRJ5j+ARKA0w4pYs5a5ufqcfT7dN6TBk LXZeD9xlVic93Ju08JSUx2ozlcfxq+BVNyA+dtv7elXUZ2DrYwARAQABzSxHdXN0YXZvIEEu IFIuIFNpbHZhIDxndXN0YXZvQGVtYmVkZGVkb3IuY29tPsLBfQQTAQgAJwUCWywcDAIbIwUJ CWYBgAULCQgHAgYVCAkKCwIEFgIDAQIeAQIXgAAKCRBHBbTLRwbbMZ6tEACk0hmmZ2FWL1Xi l/bPqDGFhzzexrdkXSfTTZjBV3a+4hIOe+jl6Rci/CvRicNW4H9yJHKBrqwwWm9fvKqOBAg9 obq753jydVmLwlXO7xjcfyfcMWyx9QdYLERTeQfDAfRqxir3xMeOiZwgQ6dzX3JjOXs6jHBP cgry90aWbaMpQRRhaAKeAS14EEe9TSIly5JepaHoVdASuxklvOC0VB0OwNblVSR2S5i5hSsh ewbOJtwSlonsYEj4EW1noQNSxnN/vKuvUNegMe+LTtnbbocFQ7dGMsT3kbYNIyIsp42B5eCu JXnyKLih7rSGBtPgJ540CjoPBkw2mCfhj2p5fElRJn1tcX2McsjzLFY5jK9RYFDavez5w3lx JFgFkla6sQHcrxH62gTkb9sUtNfXKucAfjjCMJ0iuQIHRbMYCa9v2YEymc0k0RvYr43GkA3N PJYd/vf9vU7VtZXaY4a/dz1d9dwIpyQARFQpSyvt++R74S78eY/+lX8wEznQdmRQ27kq7BJS R20KI/8knhUNUJR3epJu2YFT/JwHbRYC4BoIqWl+uNvDf+lUlI/D1wP+lCBSGr2LTkQRoU8U 64iK28BmjJh2K3WHmInC1hbUucWT7Swz/+6+FCuHzap/cjuzRN04Z3Fdj084oeUNpP6+b9yW e5YnLxF8ctRAp7K4yVlvA87BTQRbLBwMARAAsHCE31Ffrm6uig1BQplxMV8WnRBiZqbbsVJB H1AAh8tq2ULl7udfQo1bsPLGGQboJSVN9rckQQNahvHAIK8ZGfU4Qj8+CER+fYPp/MDZj+t0 DbnWSOrG7z9HIZo6PR9z4JZza3Hn/35jFggaqBtuydHwwBANZ7A6DVY+W0COEU4of7CAahQo 5NwYiwS0lGisLTqks5R0Vh+QpvDVfuaF6I8LUgQR/cSgLkR//V1uCEQYzhsoiJ3zc1HSRyOP otJTApqGBq80X0aCVj1LOiOF4rrdvQnj6iIlXQssdb+WhSYHeuJj1wD0ZlC7ds5zovXh+FfF l5qH5RFY/qVn3mNIVxeO987WSF0jh+T5ZlvUNdhedGndRmwFTxq2Li6GNMaolgnpO/CPcFpD jKxY/HBUSmaE9rNdAa1fCd4RsKLlhXda+IWpJZMHlmIKY8dlUybP+2qDzP2lY7kdFgPZRU+e zS/pzC/YTzAvCWM3tDgwoSl17vnZCr8wn2/1rKkcLvTDgiJLPCevqpTb6KFtZosQ02EGMuHQ I6Zk91jbx96nrdsSdBLGH3hbvLvjZm3C+fNlVb9uvWbdznObqcJxSH3SGOZ7kCHuVmXUcqoz ol6ioMHMb+InrHPP16aVDTBTPEGwgxXI38f7SUEn+NpbizWdLNz2hc907DvoPm6HEGCanpcA EQEAAcLBZQQYAQgADwUCWywcDAIbDAUJCWYBgAAKCRBHBbTLRwbbMdsZEACUjmsJx2CAY+QS UMebQRFjKavwXB/xE7fTt2ahuhHT8qQ/lWuRQedg4baInw9nhoPE+VenOzhGeGlsJ0Ys52sd XvUjUocKgUQq6ekOHbcw919nO5L9J2ejMf/VC/quN3r3xijgRtmuuwZjmmi8ct24TpGeoBK4 WrZGh/1hAYw4ieARvKvgjXRstcEqM5thUNkOOIheud/VpY+48QcccPKbngy//zNJWKbRbeVn imua0OpqRXhCrEVm/xomeOvl1WK1BVO7z8DjSdEBGzbV76sPDJb/fw+y+VWrkEiddD/9CSfg fBNOb1p1jVnT2mFgGneIWbU0zdDGhleI9UoQTr0e0b/7TU+Jo6TqwosP9nbk5hXw6uR5k5PF 8ieyHVq3qatJ9K1jPkBr8YWtI5uNwJJjTKIA1jHlj8McROroxMdI6qZ/wZ1ImuylpJuJwCDC ORYf5kW61fcrHEDlIvGc371OOvw6ejF8ksX5+L2zwh43l/pKkSVGFpxtMV6d6J3eqwTafL86 YJWH93PN+ZUh6i6Rd2U/i8jH5WvzR57UeWxE4P8bQc0hNGrUsHQH6bpHV2lbuhDdqo+cM9eh GZEO3+gCDFmKrjspZjkJbB5Gadzvts5fcWGOXEvuT8uQSvl+vEL0g6vczsyPBtqoBLa9SNrS VtSixD1uOgytAP7RWS474w== Message-ID: Date: Mon, 2 Mar 2020 20:04:49 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <30493b5f-752d-147f-3d64-95b1c59895ae@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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: 201.162.167.16 X-Source-L: No X-Exim-ID: 1j8wsU-002Nhr-UO X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: ([192.168.43.132]) [201.162.167.16]:17582 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 6 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/2/20 19:17, Joseph Qi wrote: > Sorry for the late replay since I've missed the original mail. > This patch looks good to me. > > Acked-by: Joseph Qi > Thanks, Joseph. -- Gustavo > On 2020/3/3 07:57, Gustavo A. R. Silva wrote: >> Hi all, >> >> Friendly ping: Who can take this? >> >> Thanks >> -- >> Gustavo >> >> On 2/13/20 10:02, 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 >>> --- >>> fs/ocfs2/journal.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c >>> index 68ba354cf361..b425f0b01dce 100644 >>> --- a/fs/ocfs2/journal.c >>> +++ b/fs/ocfs2/journal.c >>> @@ -91,7 +91,7 @@ enum ocfs2_replay_state { >>> struct ocfs2_replay_map { >>> unsigned int rm_slots; >>> enum ocfs2_replay_state rm_state; >>> - unsigned char rm_replay_slots[0]; >>> + unsigned char rm_replay_slots[]; >>> }; >>> >>> static void ocfs2_replay_map_set_state(struct ocfs2_super *osb, int state) >>> From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gustavo A. R. Silva Date: Mon, 2 Mar 2020 20:04:49 -0600 Subject: [Ocfs2-devel] [PATCH] ocfs2: Replace zero-length array with flexible-array member In-Reply-To: <30493b5f-752d-147f-3d64-95b1c59895ae@linux.alibaba.com> References: <20200213160244.GA6088@embeddedor> <1b78acd5-2b5f-55f1-5571-73f45d3c87f7@embeddedor.com> <30493b5f-752d-147f-3d64-95b1c59895ae@linux.alibaba.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Joseph Qi , Mark Fasheh , Joel Becker , Andrew Morton Cc: ocfs2-devel@oss.oracle.com, linux-kernel@vger.kernel.org On 3/2/20 19:17, Joseph Qi wrote: > Sorry for the late replay since I've missed the original mail. > This patch looks good to me. > > Acked-by: Joseph Qi > Thanks, Joseph. -- Gustavo > On 2020/3/3 07:57, Gustavo A. R. Silva wrote: >> Hi all, >> >> Friendly ping: Who can take this? >> >> Thanks >> -- >> Gustavo >> >> On 2/13/20 10:02, 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://urldefense.com/v3/__https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html__;!!GqivPVa7Brio!L0RwciXIP78A1BHW_X6fy0HxrYfZeqFYBy-b3TvW5Tm324I3fZTZo2OXDxRuEgli5H2pZw$ >>> [2] https://urldefense.com/v3/__https://github.com/KSPP/linux/issues/21__;!!GqivPVa7Brio!L0RwciXIP78A1BHW_X6fy0HxrYfZeqFYBy-b3TvW5Tm324I3fZTZo2OXDxRuEgmW0y7Pgw$ >>> [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") >>> >>> Signed-off-by: Gustavo A. R. Silva >>> --- >>> fs/ocfs2/journal.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c >>> index 68ba354cf361..b425f0b01dce 100644 >>> --- a/fs/ocfs2/journal.c >>> +++ b/fs/ocfs2/journal.c >>> @@ -91,7 +91,7 @@ enum ocfs2_replay_state { >>> struct ocfs2_replay_map { >>> unsigned int rm_slots; >>> enum ocfs2_replay_state rm_state; >>> - unsigned char rm_replay_slots[0]; >>> + unsigned char rm_replay_slots[]; >>> }; >>> >>> static void ocfs2_replay_map_set_state(struct ocfs2_super *osb, int state) >>>