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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 DBDACC76191 for ; Thu, 25 Jul 2019 18:56:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B46BA204EC for ; Thu, 25 Jul 2019 18:56:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726542AbfGYS4Z (ORCPT ); Thu, 25 Jul 2019 14:56:25 -0400 Received: from relay2-d.mail.gandi.net ([217.70.183.194]:56819 "EHLO relay2-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726416AbfGYS4V (ORCPT ); Thu, 25 Jul 2019 14:56:21 -0400 X-Originating-IP: 93.29.109.196 Received: from localhost.localdomain (196.109.29.93.rev.sfr.net [93.29.109.196]) (Authenticated sender: paul.kocialkowski@bootlin.com) by relay2-d.mail.gandi.net (Postfix) with ESMTPSA id 0144940002; Thu, 25 Jul 2019 18:56:18 +0000 (UTC) From: Paul Kocialkowski To: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, linux-arm-kernel@lists.infradead.org, linux-sunxi@googlegroups.com Cc: Mauro Carvalho Chehab , Maxime Ripard , Paul Kocialkowski , Greg Kroah-Hartman , Chen-Yu Tsai , Thomas Petazzoni , Hans Verkuil , Ezequiel Garcia , Tomasz Figa , Alexandre Courbot , Nicolas Dufresne , Boris Brezillon , Jernej Skrabec , Jonas Karlman , Sakari Ailus Subject: [PATCH v7 1/4] media: v4l2-ctrl: Add a comment on why we zero out compound controls fields Date: Thu, 25 Jul 2019 20:55:59 +0200 Message-Id: <20190725185602.22522-2-paul.kocialkowski@bootlin.com> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190725185602.22522-1-paul.kocialkowski@bootlin.com> References: <20190725185602.22522-1-paul.kocialkowski@bootlin.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since it's not necessarily very explicit why we need to zero some fields in std_validate_compound, add a comment before the function to explain why, which should help as a reminder. Signed-off-by: Paul Kocialkowski --- drivers/media/v4l2-core/v4l2-ctrls.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c index 76fa2db0e8fb..cd1ae016706f 100644 --- a/drivers/media/v4l2-core/v4l2-ctrls.c +++ b/drivers/media/v4l2-core/v4l2-ctrls.c @@ -1645,6 +1645,10 @@ static void std_log(const struct v4l2_ctrl *ctrl) #define zero_padding(s) \ memset(&(s).padding, 0, sizeof((s).padding)) +/* + * Compound controls validation requires setting unused fields/flags to zero + * in order to properly detect unchanged controls with std_equal's memcmp. + */ static int std_validate_compound(const struct v4l2_ctrl *ctrl, u32 idx, union v4l2_ctrl_ptr ptr) { -- 2.22.0