From patchwork Thu Feb 13 00:50:48 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: 11379535 X-Patchwork-Delegate: lorenzo.pieralisi@arm.com 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 16AB71805 for ; Thu, 13 Feb 2020 01:13:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE3D721739 for ; Thu, 13 Feb 2020 01:13:54 +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="O6E89Kl1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729190AbgBMBNy (ORCPT ); Wed, 12 Feb 2020 20:13:54 -0500 Received: from gateway24.websitewelcome.com ([192.185.51.202]:28313 "EHLO gateway24.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729185AbgBMBNy (ORCPT ); Wed, 12 Feb 2020 20:13:54 -0500 X-Greylist: delayed 1379 seconds by postgrey-1.27 at vger.kernel.org; Wed, 12 Feb 2020 20:13:52 EST Received: from cm16.websitewelcome.com (cm16.websitewelcome.com [100.42.49.19]) by gateway24.websitewelcome.com (Postfix) with ESMTP id 337A154AC7 for ; Wed, 12 Feb 2020 18:50:53 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 22iTj0mKb8vkB22iTjyhid; Wed, 12 Feb 2020 18:50:53 -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=oNtS80ALTefLju8sXnhUYyqruAR8Cl5rZOZKlDdi3/o=; b=O6E89Kl1z/UOh3gllATe8Wi3cR x/TDcLBjptHyATw2n2/d70Tr9OQ6VklUFJ3eo1Dch4M/zLSE3I86K4Z0l6QofCllkVSMqjzWASmgb mwO7JjC7vu/UR8xY4HZbrhTQv86mqRvXFBL/mpmKOXR6cWHbyz9qEk3s7M/Jq+VIbh1lQ3JAW2fAa g00iYXlgXl4PSG+tjDrntzMx2Lnkzp95Ydn0Llxu3ctF2XvNAbFqYBatLgJWt9CqJ/ATAcf/xiRII H4X74kdy9YqbtQ6XiZ1gi3NjY7Q2CSLPjW5wSXLL7FvRpazRxUu3ospLuWRT2i6Oyt9RwDmv78VGa 4dlntZ9w==; Received: from [200.68.141.42] (port=17629 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j22iQ-003lou-MG; Wed, 12 Feb 2020 18:50:51 -0600 Date: Wed, 12 Feb 2020 18:50:48 -0600 From: "Gustavo A. R. Silva" To: "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Sasha Levin , Lorenzo Pieralisi , Andrew Murray , Bjorn Helgaas Cc: linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] PCI: hv: Replace zero-length array with flexible-array member Message-ID: <20200213005048.GA9662@embeddedor.com> 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: 200.68.141.42 X-Source-L: No X-Exim-ID: 1j22iQ-003lou-MG X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [200.68.141.42]:17629 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 72 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@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 Reviewed-by: Dexuan Cui --- drivers/pci/controller/pci-hyperv.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index 9977abff92fc..be957268f9d6 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -260,7 +260,7 @@ struct pci_packet { int resp_packet_size); void *compl_ctxt; - struct pci_message message[0]; + struct pci_message message[]; }; /* @@ -296,7 +296,7 @@ struct pci_bus_d0_entry { struct pci_bus_relations { struct pci_incoming_message incoming; u32 device_count; - struct pci_function_description func[0]; + struct pci_function_description func[]; } __packed; struct pci_q_res_req_response { @@ -508,7 +508,7 @@ struct hv_dr_work { struct hv_dr_state { struct list_head list_entry; u32 device_count; - struct pci_function_description func[0]; + struct pci_function_description func[]; }; enum hv_pcichild_state {