From patchwork Thu May 7 19:19:43 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: 11534771 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 509AC1392 for ; Thu, 7 May 2020 19:15:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 380CC21BE5 for ; Thu, 7 May 2020 19:15:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588878922; bh=dmkjYUSRjBOU9cIkMaN7hPDyFaInZqjL3fVGYpepZAY=; h=Date:From:To:Cc:Subject:List-ID:From; b=0hZtTPMQZYA6NPk6VQ75LKibRCNuZsnYCNZWoj43HMHC05FJS20t9F8dYppUf/fzs 16e4vkWVBTjn1baejAe+GIovFf+CQSACBgGTUFOpPB/IdnKwiQMik6ePpZl4Z02vVg YzDioIQKAL4klKgROkdseUtWlSqUpgc9F1pnIG3c= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727891AbgEGTPS (ORCPT ); Thu, 7 May 2020 15:15:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:38896 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726320AbgEGTPR (ORCPT ); Thu, 7 May 2020 15:15:17 -0400 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 D16B2208E4; Thu, 7 May 2020 19:15:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588878917; bh=dmkjYUSRjBOU9cIkMaN7hPDyFaInZqjL3fVGYpepZAY=; h=Date:From:To:Cc:Subject:From; b=vDWIkb78pKi3Do4eX6sHoac2nBFhl0TvC8Bg1W7pkXVVWkLMNGuStpJvbPHZ5EE45 EsbLT7KX8Wxap4YE26VR7C8nh3j/jK+erlujs0+UyHn5XXnkbEyYtlLuhQTRQrxLm4 GKZE/vRe6vtniDmY6qeISUWHGeuIrP3Qehew8lOk= Date: Thu, 7 May 2020 14:19:43 -0500 From: "Gustavo A. R. Silva" To: Ohad Ben-Cohen , Bjorn Andersson Cc: linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] remoteproc: Replace zero-length array with flexible-array Message-ID: <20200507191943.GA16033@embeddedor> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-remoteproc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-remoteproc@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] 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 --- include/linux/remoteproc.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h index 9c07d7958c53..e6267fba00e6 100644 --- a/include/linux/remoteproc.h +++ b/include/linux/remoteproc.h @@ -73,7 +73,7 @@ struct resource_table { u32 ver; u32 num; u32 reserved[2]; - u32 offset[0]; + u32 offset[]; } __packed; /** @@ -87,7 +87,7 @@ struct resource_table { */ struct fw_rsc_hdr { u32 type; - u8 data[0]; + u8 data[]; } __packed; /** @@ -306,7 +306,7 @@ struct fw_rsc_vdev { u8 status; u8 num_of_vrings; u8 reserved[2]; - struct fw_rsc_vdev_vring vring[0]; + struct fw_rsc_vdev_vring vring[]; } __packed; struct rproc;