From patchwork Tue Mar 3 22:05:03 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: 11418867 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 CEC4114E3 for ; Tue, 3 Mar 2020 22:26:01 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 AB52B20848 for ; Tue, 3 Mar 2020 22:26:01 +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="QDxMwgoN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AB52B20848 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=embeddedor.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7104B88FC8; Tue, 3 Mar 2020 22:25:58 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org X-Greylist: delayed 1433 seconds by postgrey-1.36 at gabe; Tue, 03 Mar 2020 22:25:57 UTC Received: from gateway23.websitewelcome.com (gateway23.websitewelcome.com [192.185.49.219]) by gabe.freedesktop.org (Postfix) with ESMTPS id 41BB7890F0 for ; Tue, 3 Mar 2020 22:25:57 +0000 (UTC) Received: from cm14.websitewelcome.com (cm14.websitewelcome.com [100.42.49.7]) by gateway23.websitewelcome.com (Postfix) with ESMTP id 4B22164C97 for ; Tue, 3 Mar 2020 16:02:03 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 9Fc3jqoW6XVkQ9Fc3jAu4J; Tue, 03 Mar 2020 16:02:03 -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=Ov8U0/V3EL/OzxBcysm37ohdrH/vifyJsx+ocJmx8J0=; b=QDxMwgoNK7dQfmEmgjrj67RHGN KUJ6y4wrfcxBIYLAqMLTwTlVBO6e0kZCuWOYBfXDnIzPDcEHdyA6SAstcJbyKb5p9KDjwq/nHOf6F hmZwFD6W7wNGH5c3UwjLmvXxdcS3LNV6oBvmvBOBkO8FYQJgYEvJrUuuLdGx2Nqoh8fzGBh3aEEdW 7laQex2xlTopGAoEGzT35LvvMpREl8ispVH0YLsEswxx7tVFWSvOixDrvlCDWBUEWr/TYMhb5vGdP suhga6py/O/LfVsYySMTpW5RJf6zFW1pcsCAyo3AYzauuSe3syZbVbTZ29ZhNxT7t7S9bh1uS+mU3 PqZF287w==; Received: from [201.162.240.151] (port=26880 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j9Fbz-00118U-IR; Tue, 03 Mar 2020 16:02:00 -0600 Date: Tue, 3 Mar 2020 16:05:03 -0600 From: "Gustavo A. R. Silva" To: Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Daniel Vetter Subject: [PATCH][next] drm/i915: Replace zero-length array with flexible-array member Message-ID: <20200303220503.GA2663@embeddedor> 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 - lists.freedesktop.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 201.162.240.151 X-Source-L: No X-Exim-ID: 1j9Fbz-00118U-IR X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.162.240.151]:26880 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 7 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, "Gustavo A. R. Silva" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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: Jani Nikula --- drivers/gpu/drm/i915/display/intel_vbt_defs.h | 4 ++-- drivers/gpu/drm/i915/gt/intel_lrc.c | 2 +- drivers/gpu/drm/i915/i915_gpu_error.h | 2 +- 3 files changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_vbt_defs.h b/drivers/gpu/drm/i915/display/intel_vbt_defs.h index 05c7cbe32eb4..aef7fe932d1a 100644 --- a/drivers/gpu/drm/i915/display/intel_vbt_defs.h +++ b/drivers/gpu/drm/i915/display/intel_vbt_defs.h @@ -462,7 +462,7 @@ struct bdb_general_definitions { * number = (block_size - sizeof(bdb_general_definitions))/ * defs->child_dev_size; */ - u8 devices[0]; + u8 devices[]; } __packed; /* @@ -839,7 +839,7 @@ struct bdb_mipi_config { struct bdb_mipi_sequence { u8 version; - u8 data[0]; /* up to 6 variable length blocks */ + u8 data[]; /* up to 6 variable length blocks */ } __packed; /* diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index b9b3f78f1324..a49ddda649b9 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -216,7 +216,7 @@ struct virtual_engine { /* And finally, which physical engines this virtual engine maps onto. */ unsigned int num_siblings; - struct intel_engine_cs *siblings[0]; + struct intel_engine_cs *siblings[]; }; static struct virtual_engine *to_virtual_engine(struct intel_engine_cs *engine) diff --git a/drivers/gpu/drm/i915/i915_gpu_error.h b/drivers/gpu/drm/i915/i915_gpu_error.h index 0d1f6c8ff355..5a6561f7a210 100644 --- a/drivers/gpu/drm/i915/i915_gpu_error.h +++ b/drivers/gpu/drm/i915/i915_gpu_error.h @@ -42,7 +42,7 @@ struct i915_vma_coredump { int num_pages; int page_count; int unused; - u32 *pages[0]; + u32 *pages[]; }; struct i915_request_coredump {