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 1C4D0C77B61 for ; Thu, 13 Apr 2023 12:31:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229821AbjDMMbz (ORCPT ); Thu, 13 Apr 2023 08:31:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44652 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229705AbjDMMbv (ORCPT ); Thu, 13 Apr 2023 08:31:51 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 183AA83DD for ; Thu, 13 Apr 2023 05:31:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1681389111; x=1712925111; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=T1qN+BEy+nB1sRu7UoFdHmbhBDz2OmE2p2qIBhyTCLE=; b=lnVXeNIFHuHtjaaA9/MM165m0mD7hAAx7MEG+Y0uAHo/NWdiQMJLeHTk ql/uv6b0hQFlOV7T9v60NOhGDz9bln/I0BAVp3/fw6FMIoLsG6ajdOkaY a/cCECZkak/vT2cpefrU3EjN+CLCQtveAjT6ZZs3Mlor0Ne4N28JipPAh f9DzGI8pzk9GoXx8VmUD2nk+ORfybEhR4hHBp74n7341XaldeIqFuOFWb IsjwB99MuNsYICj+I8N+tGuE1QPYDo57SeYSOCLM5Hl4LdMioKfr71i7G e6jBalkZ+QwBtXxLybSe06KLno7RptpF/lrl1utIWP8vXI09tRHoSy/Uw A==; X-IronPort-AV: E=McAfee;i="6600,9927,10678"; a="346855151" X-IronPort-AV: E=Sophos;i="5.99,341,1677571200"; d="scan'208";a="346855151" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Apr 2023 05:31:50 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10678"; a="722039812" X-IronPort-AV: E=Sophos;i="5.99,341,1677571200"; d="scan'208";a="722039812" Received: from unknown (HELO localhost) ([10.237.66.160]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Apr 2023 05:31:47 -0700 From: Jani Nikula To: Jeff Layton , David Airlie , Daniel Vetter Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Harry Wentland , Alex Deucher Subject: Re: [PATCH] drm: make drm_dp_add_payload_part2 gracefully handle NULL state pointer In-Reply-To: <20230413111254.22458-1-jlayton@kernel.org> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20230413111254.22458-1-jlayton@kernel.org> Date: Thu, 13 Apr 2023 15:31:45 +0300 Message-ID: <87edooarpq.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 13 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. > > The real bug is probably in the caller of this function, which is > passing it a NULL state pointer, but this patch at least keeps my > machine from oopsing when this occurs. My fear is that papering over this makes the root cause harder to find. Cc: Harry, Alex BR, Jani. > > Link: https://bugzilla.redhat.com/show_bug.cgi?id=2184855 > Signed-off-by: Jeff Layton > --- > drivers/gpu/drm/display/drm_dp_mst_topology.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c > index 38dab76ae69e..87ad406c50f9 100644 > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c > @@ -3404,7 +3404,8 @@ 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(state ? state->dev : NULL, > + "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