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 E5C9CD68BCF for ; Fri, 15 Nov 2024 20:29:54 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6925410E3E1; Fri, 15 Nov 2024 20:29:54 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="GaWrZ8zT"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1390A10E3E1; Fri, 15 Nov 2024 20:29:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1731702594; x=1763238594; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=XSUv9m5qVvNMSRmKF5P6IsrVhp+zWJUrO/gtkor3KpE=; b=GaWrZ8zTP0musaNmgKLXn9g7rqsdIffoG905cVEYcx34YnJjMVa3U5QK U41bd+y5WZIsBdQvLCVEE6wAgr5L2dW3lVlDbj5PqdYRQf0uQgtusSOZy LVMXbtvbbOjBi+xaTyDG/h0urCzUAomckkJ2pMuHweP2/tIjq7uaUzNzp ioSvN6zrE/Gt0YCiEoTon+zvEscelqZh3RYLBIU7V0/Vx1zidE9Q0hVk7 dNDrtuV7rQ3aNNZNDTZvO6TrLTgDhCcc6pvNcs0XzQIk3w32nFQXXgJr8 lm8wcmncSk49eD8q4t60VvGUZLNRZsFOsm1/ANeqyMdlbldY5Ov/QmHSp g==; X-CSE-ConnectionGUID: /nMYzdlzRpGITXfwrM9xNQ== X-CSE-MsgGUID: hgC2c8+WQqGcRpVoWISruQ== X-IronPort-AV: E=McAfee;i="6700,10204,11257"; a="54229273" X-IronPort-AV: E=Sophos;i="6.12,157,1728975600"; d="scan'208";a="54229273" Received: from orviesa004.jf.intel.com ([10.64.159.144]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Nov 2024 12:29:47 -0800 X-CSE-ConnectionGUID: Kqshr5sLRRaTnHCWvk8xdA== X-CSE-MsgGUID: 88m3Nl0GSvWRKV1TCIVpbA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,157,1728975600"; d="scan'208";a="93752174" Received: from ideak-desk.fi.intel.com ([10.237.72.78]) by orviesa004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Nov 2024 12:29:46 -0800 Date: Fri, 15 Nov 2024 22:30:12 +0200 From: Imre Deak To: Rodrigo Vivi Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Jani Nikula Subject: Re: [PATCH 1/4] drm/i915/dp_mst: Fix connector initialization in intel_dp_add_mst_connector() Message-ID: References: <20241115164159.1081675-1-imre.deak@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: imre.deak@intel.com Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Fri, Nov 15, 2024 at 03:20:58PM -0500, Rodrigo Vivi wrote: > On Fri, Nov 15, 2024 at 06:41:56PM +0200, Imre Deak wrote: > > The connector initialization in intel_dp_add_mst_connector() depends on > > the device pointer in connector to be valid, at least by connector > > debug printing. The device pointer is initialized by drm_connector_init(), > > however that function also exposes the connector to in-kernel users, > > which can't be done before the connector is fully initialized. For now > > make sure the device pointer is valid before it's used, until a > > follow-up change moving this to DRM core. > > > > This issue was revealed by the commit in the Fixes: line below, before > > which the above debug printing checked and handled a NULL device pointer > > gracefully in DRM core. > > > > Cc: Jani Nikula > > Fixes: 529798bd786a ("drm/i915/mst: convert to struct intel_display") > > This is awkward. This patch actually removes callers of base.dev. > I don't see how that it could be causing this new null dereference. It adds struct intel_display *display = to_intel_display(connector); which will be NULL since connector->base.dev is NULL and later display is dereferenced. > > Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/12799 > > But well, trusting more the tests then my eyes, let's move forward. > > Reviewed-by: Rodrigo Vivi > > > Signed-off-by: Imre Deak > > --- > > drivers/gpu/drm/i915/display/intel_dp_mst.c | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c > > index df7edcfe885b6..f058360a26413 100644 > > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c > > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c > > @@ -1727,6 +1727,16 @@ static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topolo > > > > intel_dp_init_modeset_retry_work(intel_connector); > > > > + /* > > + * TODO: The following drm_connector specific initialization belongs > > + * to DRM core, however it happens atm too late in > > + * drm_connector_init(). That function will also expose the connector > > + * to in-kernel users, so it can't be called until the connector is > > + * sufficiently initialized; init the device pointer used by the > > + * following DSC setup, until a fix moving this to DRM core. > > + */ > > + intel_connector->base.dev = mgr->dev; > > + > > intel_connector->dp.dsc_decompression_aux = drm_dp_mst_dsc_aux_for_port(port); > > intel_dp_mst_read_decompression_port_dsc_caps(intel_dp, intel_connector); > > intel_connector->dp.dsc_hblank_expansion_quirk = > > -- > > 2.44.2 > >