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=-13.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 10E19C38A2A for ; Thu, 7 May 2020 21:14:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D6A3220731 for ; Thu, 7 May 2020 21:14:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588886049; bh=nDy0sEtP9kF9L34Jo/5G/mMWigMW2hNi5uXvTqim0pM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=154RsqTx+dMlb7ChwLTfc6VzZ1vWhIfBcoihIO8tEH441aMcAK2af61za1nA3b3zc ljs2bvlCZdw7FRZEjNC9kubVonjuJLCcGCYfvADYGZ3a9vg8fCx/AkmCV8rhYq7GtE nxKkZFTz+lW4B3OQ9C5QFeeXfHdCp0hDBppF1kvY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726437AbgEGVOJ (ORCPT ); Thu, 7 May 2020 17:14:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:60130 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726218AbgEGVOJ (ORCPT ); Thu, 7 May 2020 17:14:09 -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 082C420731; Thu, 7 May 2020 21:14:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588886048; bh=nDy0sEtP9kF9L34Jo/5G/mMWigMW2hNi5uXvTqim0pM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=a2yUU+AIANQ4UaVmmqQneT/ArIvzOWURsUBdTfPSmBKjwPw+HrkXe9ThyjNY1zx7T wLzdjKBW93PQ3BjJqvczVnRV0QVXUlCQlx2oxMz1uylAjh8xnFCxK3XcLUOCcXsWK5 84Y+HmMrGOCmL7pA2V+b3gyWOO8tX99O+9yyD5J4= Date: Thu, 7 May 2020 16:18:34 -0500 From: "Gustavo A. R. Silva" To: Stanimir Varbanov Cc: linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] media: venus: Replace zero-length array with flexible-array Message-ID: <20200507211834.GA20715@embeddedor> References: <20200507190750.GA15755@embeddedor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Thu, May 07, 2020 at 11:39:51PM +0300, Stanimir Varbanov wrote: > Hi Gustavo, > > Two patches from you are already queued in media_tree for v5.8. > Awesome. :) Thanks, Stanimir. -- Gustavo > 0f61e171e4bbac4595175070c75707f1b12f4e37 media: venus: hfi_msgs.h: > Replace zero-length array with flexible-array member > > 380f3bbd9562dc93be2e3cadc329b15284fbedae media: venus: hfi_cmds.h: > Replace zero-length array with flexible-array member > > > On 5/7/20 10:07 PM, 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] > > > > 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/media/platform/qcom/venus/hfi_cmds.h | 2 +- > > drivers/media/platform/qcom/venus/hfi_msgs.h | 10 +++++----- > > 2 files changed, 6 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/media/platform/qcom/venus/hfi_cmds.h b/drivers/media/platform/qcom/venus/hfi_cmds.h > > index cae9d5d61c0c..83705e237f1c 100644 > > --- a/drivers/media/platform/qcom/venus/hfi_cmds.h > > +++ b/drivers/media/platform/qcom/venus/hfi_cmds.h > > @@ -107,7 +107,7 @@ struct hfi_session_abort_pkt { > > struct hfi_session_set_property_pkt { > > struct hfi_session_hdr_pkt shdr; > > u32 num_properties; > > - u32 data[0]; > > + u32 data[]; > > }; > > > > struct hfi_session_set_buffers_pkt { > > diff --git a/drivers/media/platform/qcom/venus/hfi_msgs.h b/drivers/media/platform/qcom/venus/hfi_msgs.h > > index 7694b1d25d9d..526d9f5b487b 100644 > > --- a/drivers/media/platform/qcom/venus/hfi_msgs.h > > +++ b/drivers/media/platform/qcom/venus/hfi_msgs.h > > @@ -155,7 +155,7 @@ struct hfi_msg_session_empty_buffer_done_pkt { > > u32 input_tag; > > u32 packet_buffer; > > u32 extradata_buffer; > > - u32 data[0]; > > + u32 data[]; > > }; > > > > struct hfi_msg_session_fbd_compressed_pkt { > > @@ -175,7 +175,7 @@ struct hfi_msg_session_fbd_compressed_pkt { > > u32 picture_type; > > u32 packet_buffer; > > u32 extradata_buffer; > > - u32 data[0]; > > + u32 data[]; > > }; > > > > struct hfi_msg_session_fbd_uncompressed_plane0_pkt { > > @@ -202,7 +202,7 @@ struct hfi_msg_session_fbd_uncompressed_plane0_pkt { > > u32 picture_type; > > u32 packet_buffer; > > u32 extradata_buffer; > > - u32 data[0]; > > + u32 data[]; > > }; > > > > struct hfi_msg_session_fbd_uncompressed_plane1_pkt { > > @@ -211,7 +211,7 @@ struct hfi_msg_session_fbd_uncompressed_plane1_pkt { > > u32 filled_len; > > u32 offset; > > u32 packet_buffer2; > > - u32 data[0]; > > + u32 data[]; > > }; > > > > struct hfi_msg_session_fbd_uncompressed_plane2_pkt { > > @@ -220,7 +220,7 @@ struct hfi_msg_session_fbd_uncompressed_plane2_pkt { > > u32 filled_len; > > u32 offset; > > u32 packet_buffer3; > > - u32 data[0]; > > + u32 data[]; > > }; > > > > struct hfi_msg_session_parse_sequence_header_done_pkt { > > > > -- > regards, > Stan