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 C6160C44515 for ; Fri, 17 Jul 2026 20:07:04 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 2007E10E4DE; Fri, 17 Jul 2026 20:07:04 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=bootlin.com header.i=@bootlin.com header.b="xNB33+mz"; dkim-atps=neutral Received: from smtpout-02.galae.net (smtpout-02.galae.net [185.246.84.56]) by gabe.freedesktop.org (Postfix) with ESMTPS id D2C9410E4DE for ; Fri, 17 Jul 2026 20:07:02 +0000 (UTC) Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-02.galae.net (Postfix) with ESMTPS id 04BEF1A1077; Fri, 17 Jul 2026 20:07:01 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id CAB6160361; Fri, 17 Jul 2026 20:07:00 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id F35BF11BD013E; Fri, 17 Jul 2026 22:06:52 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1784318819; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=Wi6BQXLKQhiTifAq9gxYfAkWMFRwEzXZVKdz6vQCO6g=; b=xNB33+mzXBMshQjizeo3TN2jPxVuCW1lwKEfonhroQzwgjcCtDDv7/UuW2b8jugzJ7uOWP FzSwAUYWASfPIZMpSVfd1cvemr5Nh6YKswabLkTNhweI7+JXBN+417vk3IfTs1zeT6GUxV E1mmsmgi0vbm3YxX3lXHWSGufVZEjC5QWO9tOmBW1zkWls9mOcRMJT5+gFiiWjleACZF3S 5gniqFIMkuMg+Xh6kEETLedAEZOomBXxcfwsSXg9ZJ2/3mRIrRzn9Cu4GQl5XOMk7zw819 NAg3aKj9k1ZBa8+zwm0BW/yJTJKtQ/NwHm70Ns+Wger32LngZJhaC4EC+yXNIw== Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Fri, 17 Jul 2026 22:06:51 +0200 Message-Id: From: "Luca Ceresoli" Subject: Re: [PATCH 2/4] drm/bridge: display-connector: Fix I2C adapter resource leak Cc: "Johan Hovold" , , , "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" , , To: "Laurent Pinchart" , "Luca Ceresoli" X-Mailer: aerc 0.21.0 References: <20260705213542.28987-1-laurent.pinchart+renesas@ideasonboard.com> <20260705213542.28987-3-laurent.pinchart+renesas@ideasonboard.com> <20260717182802.GD1889304@killaraus.ideasonboard.com> In-Reply-To: <20260717182802.GD1889304@killaraus.ideasonboard.com> X-Last-TLS-Session-Version: TLSv1.3 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" Hi Laurent, On Fri Jul 17, 2026 at 8:28 PM CEST, Laurent Pinchart wrote: > 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 releas= ing >> >> 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.or= g/ >> > >> >> 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. Makes sense indeed. Thanks for the clarification. Luca -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com