From patchwork Thu May 7 19:07:50 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: 63664 Received: from vger.kernel.org ([23.128.96.18]) by www.linuxtv.org with esmtp (Exim 4.92) (envelope-from ) id 1jWlkd-00GJwZ-Nz; Thu, 07 May 2020 19:00:08 +0000 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727891AbgEGTDY (ORCPT + 1 other); Thu, 7 May 2020 15:03:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:33676 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726367AbgEGTDY (ORCPT ); Thu, 7 May 2020 15:03:24 -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 2D7FE2083B; Thu, 7 May 2020 19:03:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588878203; bh=hDrhDJ+9+p7V0p39p+wAiF1BD0xFcVR0UNXHEixFP8Y=; h=Date:From:To:Cc:Subject:From; b=E7TMDbft1Dv7fxo6+nlAZ+ThbNi/6sm0iSirDV/cgElpudWvzkztchzb4ZH1quic2 BYcnmjQOWzzohH4P9QwN5wb2ngO5gceV3FCZU+xk/AuVvYcdqRkMj5rDO3lG0+6WDW eum6FARUXDlyK33hw53WysF9cyVMnch5R39tDOqk= Date: Thu, 7 May 2020 14:07:50 -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: [PATCH] media: venus: Replace zero-length array with flexible-array Message-ID: <20200507190750.GA15755@embeddedor> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-LSpam-Score: -3.1 (---) X-LSpam-Report: No, score=-3.1 required=5.0 tests=BAYES_00=-1.9,DKIMWL_WL_HIGH=0.001,DKIM_SIGNED=0.1,DKIM_VALID=-0.1,DKIM_VALID_AU=-0.1,DKIM_VALID_EF=-0.1,MAILING_LIST_MULTI=-1 autolearn=ham autolearn_force=no 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 {