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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 9EE7DC44515 for ; Fri, 17 Jul 2026 18:28:08 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id BA4A910E3D5; Fri, 17 Jul 2026 18:28:07 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="R7STgd6L"; dkim-atps=neutral Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by gabe.freedesktop.org (Postfix) with ESMTPS id CFB5C10E2F5 for ; Fri, 17 Jul 2026 18:28:05 +0000 (UTC) Received: from killaraus.ideasonboard.com (2001-14ba-70f3-e800--a06.rev.dnainternet.fi [IPv6:2001:14ba:70f3:e800::a06]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 848A3664; Fri, 17 Jul 2026 20:27:07 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1784312827; bh=cY72Q3eaRUqzShiCt1IhCPUROEqqx3q2tARINzYOV4E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=R7STgd6L+KOgQCiaKfyd7K6xlKz0oKgSyLncZv15XbVpe7f8XdcG6/yZywtz/cnPJ FEUE/B2JxA4axWgncKM7reSaVprTV0eA/ixjWhhY1SToj65R2WXm/w5KUXPe77/CZj yyBRUcU113yN8RFmRgtdLk+8Gk88+OXbIMwue1zI= Date: Fri, 17 Jul 2026 21:28:02 +0300 From: Laurent Pinchart To: Luca Ceresoli Cc: Johan Hovold , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, Thuan Nguyen , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Geert Uytterhoeven , Magnus Damm , Andrzej Hajda , Neil Armstrong , Robert Foss , Jonas Karlman , Jernej Skrabec , linux-renesas-soc@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 2/4] drm/bridge: display-connector: Fix I2C adapter resource leak Message-ID: <20260717182802.GD1889304@killaraus.ideasonboard.com> References: <20260705213542.28987-1-laurent.pinchart+renesas@ideasonboard.com> <20260705213542.28987-3-laurent.pinchart+renesas@ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: 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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Fri, Jul 17, 2026 at 05:21:11PM +0200, Luca Ceresoli wrote: > On Fri Jul 17, 2026 at 5:03 PM CEST, Johan Hovold wrote: > > On Mon, Jul 06, 2026 at 12:35:40AM +0300, Laurent Pinchart wrote: > >> If the probe function returns an error after getting the I2C adapter for > >> DDC, the reference to the adapter is never released. Fix it by releasing > >> it in the bridge .destroy() handler. > >> > >> There is no need to test the ddc pointer with !IS_ERR(), as > >> of_get_i2c_adapter_by_node() returns NULL on error. > > > > I stumbled over this this morning as well and posted a fix here (which > > releases the adapter on driver unbind as is currently done): > > > > https://lore.kernel.org/lkml/20260717085716.1619275-1-johan@kernel.org/ > > > >> Fixes: 6de79dd3a920 ("drm/bridge: display-connector: add ddc-en gpio support") > > > > I believe this issue was first introduced by commit 2e2bf3a5584d > > ("drm/bridge: display-connector: add DP support") a few releases > > earlier. > > > >> Cc: stable@vger.kernel.org > >> Signed-off-by: Laurent Pinchart > > > > Reviewed-by: Johan Hovold > > While Johan's patch has the benefit of putting the i2c adapter at remove > time (as opposed to destroy time, which is potentially a long time later), > it is also more complex. So I'd say this patch is fine. In this case putting the I2C adapter early is probably fine, but in general I really prefer reference-counting and releasing references at destroy time. This ensures that the resources stay available if they need to be accessed between .remove() and destruction (for instance in a .release() handler following a close() or munmap() from userspace). I think late release should be the default, as it's safer, and early release should be carefully reviewed when it's required. > Maybe we should have a devm version of of_get_i2c_adapter_by_node() to make > it all simpler. > > Reviewed-by: Luca Ceresoli -- Regards, Laurent Pinchart