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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6553CC2BA19 for ; Wed, 15 Apr 2020 11:31:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3FD8020768 for ; Wed, 15 Apr 2020 11:31:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586950311; bh=8DdcE+hkjP0fA40GmH1jQQ2XQkzxs/+J927vI9x0+KQ=; h=Subject:To:Cc:From:Date:List-ID:From; b=a4nSBZO9QHy2U+WeFH2PtGSQKWz/9vpLo9CfD2YloGt1VVue+pfmXVU+bYMAtfFNH wUnzTe2QZCFijg8Zmj2oBfHVeE2LpdpJ/7NZ+7fpavtTZwR19SYmsUN6QfKLJmmdUz Nf2yFoSRdIClGjFWf9RceHRiWTio7GDkmPH8cWuI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2896998AbgDOLbr (ORCPT ); Wed, 15 Apr 2020 07:31:47 -0400 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:57071 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2897001AbgDOLbk (ORCPT ); Wed, 15 Apr 2020 07:31:40 -0400 Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailout.nyi.internal (Postfix) with ESMTP id 214DD5C0143; Wed, 15 Apr 2020 07:31:39 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute1.internal (MEProxy); Wed, 15 Apr 2020 07:31:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=CU0lRw FAguZQWNBeO83osmk7Y487pkyO0vMNGIh+TvQ=; b=o/uEYSGN9za+269NlvLYrn YvxycgvOAe/wXtDuxY6QdANFwFTO2F2SxkIceXKVAmRSkHH7NBR+60IYeUqE5dDS Hax675c96Oe0WLwUmdE7/DUoaYFJcnDwQvZWXicJAVj0U56EeZbynGl3CttWruvW RDToyEdIhAapOIICMMQBfybEJZ1Mj5cTBaRuwIi9maFubROBb98tThpZAg8GI44y ClWp5a9fGpzUAEoNOc+zN6QMAijaIPyTdYPaghuw8k84ahNhUkNCA79SijafNRhR +fE3JgfaknNz7aGULsyvK3IpzkH1qmM5vIzLA3L077NmOMMfr/8vzbCpqqOSVlBw == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduhedrfeefgddvlecutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecunecujfgurhepuffvhfffkfggtgfgsehtkeertddttd ejnecuhfhrohhmpeeoghhrvghgkhhhsehlihhnuhigfhhouhhnuggrthhiohhnrdhorhhg qeenucffohhmrghinhepfhhrvggvuggvshhkthhophdrohhrghenucfkphepkeefrdekie drkeelrddutdejnecuvehluhhsthgvrhfuihiivgepudenucfrrghrrghmpehmrghilhhf rhhomhepghhrvghgsehkrhhorghhrdgtohhm X-ME-Proxy: Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) by mail.messagingengine.com (Postfix) with ESMTPA id B27BF306005B; Wed, 15 Apr 2020 07:31:38 -0400 (EDT) Subject: FAILED: patch "[PATCH] drm/dp_mst: Fix clearing payload state on topology disable" failed to apply to 5.4-stable tree To: lyude@redhat.com, Wayne.Lin@amd.com, sean@poorly.run, ville.syrjala@linux.intel.com Cc: From: Date: Wed, 15 Apr 2020 13:31:34 +0200 Message-ID: <158695029492138@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 8732fe46b20c951493bfc4dba0ad08efdf41de81 Mon Sep 17 00:00:00 2001 From: Lyude Paul Date: Wed, 22 Jan 2020 14:43:20 -0500 Subject: [PATCH] drm/dp_mst: Fix clearing payload state on topology disable MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The issues caused by: commit 64e62bdf04ab ("drm/dp_mst: Remove VCPI while disabling topology mgr") Prompted me to take a closer look at how we clear the payload state in general when disabling the topology, and it turns out there's actually two subtle issues here. The first is that we're not grabbing &mgr.payload_lock when clearing the payloads in drm_dp_mst_topology_mgr_set_mst(). Seeing as the canonical lock order is &mgr.payload_lock -> &mgr.lock (because we always want &mgr.lock to be the inner-most lock so topology validation always works), this makes perfect sense. It also means that -technically- there could be racing between someone calling drm_dp_mst_topology_mgr_set_mst() to disable the topology, along with a modeset occurring that's modifying the payload state at the same time. The second is the more obvious issue that Wayne Lin discovered, that we're not clearing proposed_payloads when disabling the topology. I actually can't see any obvious places where the racing caused by the first issue would break something, and it could be that some of our higher-level locks already prevent this by happenstance, but better safe then sorry. So, let's make it so that drm_dp_mst_topology_mgr_set_mst() first grabs &mgr.payload_lock followed by &mgr.lock so that we never race when modifying the payload state. Then, we also clear proposed_payloads to fix the original issue of enabling a new topology with a dirty payload state. This doesn't clear any of the drm_dp_vcpi structures, but those are getting destroyed along with the ports anyway. Changes since v1: * Use sizeof(mgr->payloads[0])/sizeof(mgr->proposed_vcpis[0]) instead - vsyrjala Cc: Sean Paul Cc: Wayne Lin Cc: Ville Syrjälä Cc: stable@vger.kernel.org # v4.4+ Signed-off-by: Lyude Paul Reviewed-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20200122194321.14953-1-lyude@redhat.com diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index e78c73e975ed..4104f15f4594 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -3447,6 +3447,7 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms int ret = 0; struct drm_dp_mst_branch *mstb = NULL; + mutex_lock(&mgr->payload_lock); mutex_lock(&mgr->lock); if (mst_state == mgr->mst_state) goto out_unlock; @@ -3505,7 +3506,10 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms /* this can fail if the device is gone */ drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0); ret = 0; - memset(mgr->payloads, 0, mgr->max_payloads * sizeof(struct drm_dp_payload)); + memset(mgr->payloads, 0, + mgr->max_payloads * sizeof(mgr->payloads[0])); + memset(mgr->proposed_vcpis, 0, + mgr->max_payloads * sizeof(mgr->proposed_vcpis[0])); mgr->payload_mask = 0; set_bit(0, &mgr->payload_mask); mgr->vcpi_mask = 0; @@ -3514,6 +3518,7 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms out_unlock: mutex_unlock(&mgr->lock); + mutex_unlock(&mgr->payload_lock); if (mstb) drm_dp_mst_topology_put_mstb(mstb); return ret;