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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F00BFC77B73 for ; Wed, 19 Apr 2023 13:21:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232715AbjDSNVU (ORCPT ); Wed, 19 Apr 2023 09:21:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57138 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233409AbjDSNVP (ORCPT ); Wed, 19 Apr 2023 09:21:15 -0400 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8FC581544C for ; Wed, 19 Apr 2023 06:21:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1681910467; x=1713446467; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=sQu+EGztomOf0wJcq47X3hsD6fAQUa1otr26HmJHEN4=; b=nqV5bYaB161Clgn7aMvT7Dv6lVH4/R1s2SuDead70LNPrUX1b5Qg8AM3 lWJWZAjdQSCYBLRODm4Dgg8oMBt2AuM3Z7cgUDrsmV9cPSP5bEes9Orrb 8o1eeSDVXCFCc3e/FvAfBTQ+KGTcDailzCIh/wnQQBWWf51+0zMfOH91W /D0W/haK3RkrHs3pVuO644uRpwKRAauCuyj/xT58Ei+3kGX3b1VDoja9X 7dvleQOVWqFqt3yKLrCp9wRgXgNKk23+O+du8SEu3X65qxljOpTRMBYsM MCxk7MrSv2s2Mu8Iw0qSTOKJzzLRAq8oAPa8LSNP2wDRsvvtZ7TadIxpM A==; X-IronPort-AV: E=McAfee;i="6600,9927,10685"; a="345445526" X-IronPort-AV: E=Sophos;i="5.99,208,1677571200"; d="scan'208";a="345445526" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Apr 2023 06:21:07 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10685"; a="802916028" X-IronPort-AV: E=Sophos;i="5.99,208,1677571200"; d="scan'208";a="802916028" Received: from yedidyal-mobl1.ger.corp.intel.com (HELO localhost) ([10.252.47.37]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Apr 2023 06:21:04 -0700 From: Jani Nikula To: Jeff Layton , David Airlie , Daniel Vetter Cc: Wayne.Lin@amd.com, lyude@redhat.com, alexdeucher@gmail.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] drm: use mgr->dev in drm_dbg_kms in drm_dp_add_payload_part2 In-Reply-To: <20230419112447.18471-1-jlayton@kernel.org> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20230419112447.18471-1-jlayton@kernel.org> Date: Wed, 19 Apr 2023 16:21:03 +0300 Message-ID: <87o7nkypmo.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 19 Apr 2023, Jeff Layton wrote: > I've been experiencing some intermittent crashes down in the display > driver code. The symptoms are ususally a line like this in dmesg: > > amdgpu 0000:30:00.0: [drm] Failed to create MST payload for port 000000006d3a3885: -5 > > ...followed by an Oops due to a NULL pointer dereference. > > Switch to using mgr->dev instead of state->dev since "state" can be > NULL in some cases. > > Link: https://bugzilla.redhat.com/show_bug.cgi?id=2184855 > Suggested-by: Jani Nikula > Signed-off-by: Jeff Layton Thanks, Reviewed-by: Jani Nikula > --- > drivers/gpu/drm/display/drm_dp_mst_topology.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > I've been running this patch for a couple of days, but the problem > hasn't occurred again as of yet. It seems sane though as long as we can > assume that mgr->dev will be valid even when "state" is a NULL pointer. > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c > index 38dab76ae69e..e2e21ce79510 100644 > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c > @@ -3404,7 +3404,7 @@ int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr, > > /* Skip failed payloads */ > if (payload->vc_start_slot == -1) { > - drm_dbg_kms(state->dev, "Part 1 of payload creation for %s failed, skipping part 2\n", > + drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s failed, skipping part 2\n", > payload->port->connector->name); > return -EIO; > } -- Jani Nikula, Intel Open Source Graphics Center