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=-13.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 DD31BC38A2A for ; Thu, 7 May 2020 19:00:47 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A4BDE2083B for ; Thu, 7 May 2020 19:00:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="DDDAmo8d"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="qn6cRKwY" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A4BDE2083B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Subject:To:From :Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=IXP5mu81MyXoSJmuHuxeJBszlVhTLHfn6NdyadYq/H0=; b=DDDAmo8dHTFjY1 ZCzrae4Ypgxwq0x9FmbU7C5rm/R65orV4NElFNKcPA5wlYFQ3s+rVso34OoVxFjw4zLlwSPnpj3DD 7BlmPVu5FEnj6nkJNMYw0ZqrefjwIm7Twbb5tR8jgSekVX2rKswnOHNyqUCiaCvBthnXoyC//txuy mgPIkkMUKClQlsNTAxk+7pd0yf3OEIRDhv462zAGINbGLqdZRucvfCUuQ5G5xwetTv2WllrU4IUNQ cZ6MQL+XXl2B8zWTnLGs4cNm9k4IuVYZeU+Hprmpip/C8v7Zw3ooKKo4OgMW+oMIpkK659gNnW8nV pUlvuCtuoDDYQSZ23Eqw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWllD-0006MM-Oy; Thu, 07 May 2020 19:00:43 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWlkw-0006DI-FR for linux-nvme@lists.infradead.org; Thu, 07 May 2020 19:00:29 +0000 Received: from embeddedor (unknown [189.207.59.248]) (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 672612083B; Thu, 7 May 2020 19:00:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588878025; bh=R5UAo0X2wUIkcPu2bAHYaMr9+zALVRcFirsDyRQuvAA=; h=Date:From:To:Cc:Subject:From; b=qn6cRKwYPaaWKY02MVF/8V8omrkz4xrVRvn2mw1GgLEW7gI9lUssG9pLlKKk2VhXv 5lnk1EO5WSRyv2MHzvSJVPLTRNEPsu7qB/FSmbaEWWBcjh6O7k+szJmk8I8vkNwwhZ wlNH83fi8M3q2rmCoHlvy3jMpsr/dYfz/ln8iMIc= Date: Thu, 7 May 2020 14:04:52 -0500 From: "Gustavo A. R. Silva" To: Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg Subject: [PATCH] lightnvm: Replace zero-length array with flexible-array Message-ID: <20200507190452.GA15449@embeddedor> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200507_120026_675443_3B0E3A03 X-CRM114-Status: GOOD ( 14.05 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.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] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. 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/nvme/host/lightnvm.c | 2 +- include/linux/nvme.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c index ec46693f6b64..3002bf972c6b 100644 --- a/drivers/nvme/host/lightnvm.c +++ b/drivers/nvme/host/lightnvm.c @@ -171,7 +171,7 @@ struct nvme_nvm_bb_tbl { __le32 tdresv; __le32 thresv; __le32 rsvd2[8]; - __u8 blk[0]; + __u8 blk[]; }; struct nvme_nvm_id20_addrf { diff --git a/include/linux/nvme.h b/include/linux/nvme.h index 3d5189f46cb1..6ee80a44ed4f 100644 --- a/include/linux/nvme.h +++ b/include/linux/nvme.h @@ -1177,7 +1177,7 @@ struct nvmf_disc_rsp_page_hdr { __le64 numrec; __le16 recfmt; __u8 resv14[1006]; - struct nvmf_disc_rsp_page_entry entries[0]; + struct nvmf_disc_rsp_page_entry entries[]; }; enum { _______________________________________________ linux-nvme mailing list linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme