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 2760CC4BA24 for ; Wed, 26 Feb 2020 22:40:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E114521D7E for ; Wed, 26 Feb 2020 22:40:12 +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="hCADqENh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727909AbgBZWkL (ORCPT ); Wed, 26 Feb 2020 17:40:11 -0500 Received: from gateway33.websitewelcome.com ([192.185.146.82]:11041 "EHLO gateway33.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727761AbgBZWkL (ORCPT ); Wed, 26 Feb 2020 17:40:11 -0500 Received: from cm14.websitewelcome.com (cm14.websitewelcome.com [100.42.49.7]) by gateway33.websitewelcome.com (Postfix) with ESMTP id 8F00715B35B for ; Wed, 26 Feb 2020 16:16:04 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 74yKjH1JjXVkQ74yKjcEAu; Wed, 26 Feb 2020 16:16:04 -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=iwW0dApQ5yAnOnmF+6lbbYBgyBKaN9DrJebNM5E7uxM=; b=hCADqENhZTZqCnQTP3PsmAwVNY rvwOiAsyS6T8NB4XghKYvwgx3npERwE1jycy1p0TmR3J4P6jRVKafdPCCZw8osUjJMmsaH5VO/SWa iaigMiSIayZ//rBks9ziwLmpnMUqDe9OxTN8Pu5bfsBdEuj7nwsPbcdhvDiWpIqEG0T7SwF2RyCFi HOwM2CX8VNXISnSOVNAvWBGX4J2aUHDbgKgGFURy/8gnedh8Kv19JGpp8MzpXKsqNk5HYVD5cQpT2 kbtwr0utytsezkhgyNyc3STVdh+UVLwXGeLhi07MoAasUJaJ5E+1kRY0nbi+Cquth0jlvOiUJRl/j aqePVpAg==; Received: from [201.166.157.3] (port=49744 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j74xY-001FWg-98; Wed, 26 Feb 2020 16:15:23 -0600 Date: Wed, 26 Feb 2020 16:18:04 -0600 From: "Gustavo A. R. Silva" To: Alasdair Kergon , Mike Snitzer , "dm-devel@redhat.comSong Liu" Cc: linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] md: Replace zero-length array with flexible-array member Message-ID: <20200226221804.GA8564@embeddedor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii 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: 201.166.157.3 X-Source-L: No X-Exim-ID: 1j74xY-001FWg-98 X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.166.157.3]:49744 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 4 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 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/md/dm-crypt.c | 2 +- drivers/md/dm-integrity.c | 2 +- drivers/md/dm-log-writes.c | 2 +- drivers/md/dm-raid.c | 2 +- drivers/md/dm-raid1.c | 2 +- drivers/md/dm-stats.c | 2 +- drivers/md/dm-stripe.c | 2 +- drivers/md/dm-switch.c | 2 +- drivers/md/md-linear.h | 2 +- drivers/md/persistent-data/dm-btree-internal.h | 2 +- drivers/md/raid1.h | 2 +- drivers/md/raid10.h | 2 +- 12 files changed, 12 insertions(+), 12 deletions(-) diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 1c641efeeca7..bea260a82a2a 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -212,7 +212,7 @@ struct crypt_config { struct mutex bio_alloc_lock; u8 *authenc_key; /* space for keys in authenc() format (if used) */ - u8 key[0]; + u8 key[]; }; #define MIN_IOS 64 diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c index b225b3e445fa..e22e6d65862a 100644 --- a/drivers/md/dm-integrity.c +++ b/drivers/md/dm-integrity.c @@ -89,7 +89,7 @@ struct journal_entry { } s; __u64 sector; } u; - commit_id_t last_bytes[0]; + commit_id_t last_bytes[]; /* __u8 tag[0]; */ }; diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c index 99721c76225d..9e21df5bb998 100644 --- a/drivers/md/dm-log-writes.c +++ b/drivers/md/dm-log-writes.c @@ -127,7 +127,7 @@ struct pending_block { char *data; u32 datalen; struct list_head list; - struct bio_vec vecs[0]; + struct bio_vec vecs[]; }; struct per_bio_data { diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c index 9a18bef0a5ff..10e8b2fe787b 100644 --- a/drivers/md/dm-raid.c +++ b/drivers/md/dm-raid.c @@ -254,7 +254,7 @@ struct raid_set { int mode; } journal_dev; - struct raid_dev dev[0]; + struct raid_dev dev[]; }; static void rs_config_backup(struct raid_set *rs, struct rs_layout *l) diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c index 089aed57e083..2f655d9f4200 100644 --- a/drivers/md/dm-raid1.c +++ b/drivers/md/dm-raid1.c @@ -83,7 +83,7 @@ struct mirror_set { struct work_struct trigger_event; unsigned nr_mirrors; - struct mirror mirror[0]; + struct mirror mirror[]; }; DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(raid1_resync_throttle, diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c index 71417048256a..35d368c418d0 100644 --- a/drivers/md/dm-stats.c +++ b/drivers/md/dm-stats.c @@ -56,7 +56,7 @@ struct dm_stat { size_t percpu_alloc_size; size_t histogram_alloc_size; struct dm_stat_percpu *stat_percpu[NR_CPUS]; - struct dm_stat_shared stat_shared[0]; + struct dm_stat_shared stat_shared[]; }; #define STAT_PRECISE_TIMESTAMPS 1 diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c index 63bbcc20f49a..51fbfcf8efa1 100644 --- a/drivers/md/dm-stripe.c +++ b/drivers/md/dm-stripe.c @@ -41,7 +41,7 @@ struct stripe_c { /* Work struct used for triggering events*/ struct work_struct trigger_event; - struct stripe stripe[0]; + struct stripe stripe[]; }; /* diff --git a/drivers/md/dm-switch.c b/drivers/md/dm-switch.c index 8a0f057b8122..bff4c7fa1cd2 100644 --- a/drivers/md/dm-switch.c +++ b/drivers/md/dm-switch.c @@ -53,7 +53,7 @@ struct switch_ctx { /* * Array of dm devices to switch between. */ - struct switch_path path_list[0]; + struct switch_path path_list[]; }; static struct switch_ctx *alloc_switch_ctx(struct dm_target *ti, unsigned nr_paths, diff --git a/drivers/md/md-linear.h b/drivers/md/md-linear.h index 8381d651d4ed..24e97db50ebb 100644 --- a/drivers/md/md-linear.h +++ b/drivers/md/md-linear.h @@ -12,6 +12,6 @@ struct linear_conf struct rcu_head rcu; sector_t array_sectors; int raid_disks; /* a copy of mddev->raid_disks */ - struct dev_info disks[0]; + struct dev_info disks[]; }; #endif diff --git a/drivers/md/persistent-data/dm-btree-internal.h b/drivers/md/persistent-data/dm-btree-internal.h index a240990a7f33..f4e644dd8101 100644 --- a/drivers/md/persistent-data/dm-btree-internal.h +++ b/drivers/md/persistent-data/dm-btree-internal.h @@ -38,7 +38,7 @@ struct node_header { struct btree_node { struct node_header header; - __le64 keys[0]; + __le64 keys[]; } __packed; diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h index e7ccad898736..b7eb09e8c025 100644 --- a/drivers/md/raid1.h +++ b/drivers/md/raid1.h @@ -180,7 +180,7 @@ struct r1bio { * if the IO is in WRITE direction, then multiple bios are used. * We choose the number when they are allocated. */ - struct bio *bios[0]; + struct bio *bios[]; /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/ }; diff --git a/drivers/md/raid10.h b/drivers/md/raid10.h index d3eaaf3eb1bc..79cd2b7d3128 100644 --- a/drivers/md/raid10.h +++ b/drivers/md/raid10.h @@ -153,7 +153,7 @@ struct r10bio { }; sector_t addr; int devnum; - } devs[0]; + } devs[]; }; /* bits for r10bio.state */ -- 2.25.0