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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 100A7C432C2 for ; Wed, 25 Sep 2019 19:27:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BC01A21D7B for ; Wed, 25 Sep 2019 19:27:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=poorly.run header.i=@poorly.run header.b="Ml8ihUom" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732746AbfIYT1x (ORCPT ); Wed, 25 Sep 2019 15:27:53 -0400 Received: from mail-yw1-f66.google.com ([209.85.161.66]:39659 "EHLO mail-yw1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729004AbfIYT1w (ORCPT ); Wed, 25 Sep 2019 15:27:52 -0400 Received: by mail-yw1-f66.google.com with SMTP id n11so2493855ywn.6 for ; Wed, 25 Sep 2019 12:27:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=poorly.run; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=mWndbsM2FZW9DDrmc2MGJhzen2bAvM4kGyMpUj+NkzE=; b=Ml8ihUomZRhj9lVSe+tvianRg9+2nGEqpd1LUcunAvxjytWmO5bHRkjUZSxxvKp1Dn HFH8GlS18gzV2e2Emq4uM1O9QR3q5Bt9ApXknDAx6QZ19C7mZTQSB60tM3uUuyOFKqpu K7oYz4QK1SK7i2b8LlFVNQPSXX7yaBuEO4hQ3CtlWbPgTTDjpGJkhzk0EthMD80J4e1Y Z2C7JfRO/PepxRrKobB+BIKMtEo/tABm0ttIRiQi//LUo+z4C/MC0VB3jSNdwumePis8 Kfvaoyoa7sgdk8JqSs6421Yss8imBNUzYOviwVLl55rJtNIfG5lQrXyem+a7C2DPpP3D fPrQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=mWndbsM2FZW9DDrmc2MGJhzen2bAvM4kGyMpUj+NkzE=; b=GT2WxjaHO6MKA+iTwedBZ/2EgkkTjddXFFbjbspcEoVLoXo4SyMj42QIy9m1cvCAiM V3TDcPxk0nx/Hnwk64xBRsvKM38hvhK8pz2mCVmX1HGTVrKZYVOfk0ZsgAeUHOGWNX1G FA7HADex7FbChWF/3v0ketRNzXbs3ZwG4IGjKKnn4BZYsLWITKQsc41iVqnScqXatoGi AbxS5NohX5VPCjqWz4lYMcb+r8Md14g8tesvp1essCBY8rbBNc1MwP/QGBKXaLret1Sg 9wIruuir5QYEAX+M+BkOpLF+9Yz6nxj3e6dubE8SgV7M4ZsDIHdHxxqDbA0EziY4ExYc /3sA== X-Gm-Message-State: APjAAAUkWsIgCp/zstkYAytetdkvlGkPXNxyayqilXjzHNiGrA9UmTyo WVDQhSNYvtpAy+9jqP7teQ8SMw== X-Google-Smtp-Source: APXvYqwa0LW1jQEtWq9nMkj2OmNFRVtcjWO6MZCX0fVithFixjuBTJBYt+Cc2B7LgfnimYwaz93ySg== X-Received: by 2002:a81:1c4:: with SMTP id 187mr7470954ywb.363.1569439671493; Wed, 25 Sep 2019 12:27:51 -0700 (PDT) Received: from localhost ([2620:0:1013:11:89c6:2139:5435:371d]) by smtp.gmail.com with ESMTPSA id 5sm1387713ywb.73.2019.09.25.12.27.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Sep 2019 12:27:50 -0700 (PDT) Date: Wed, 25 Sep 2019 15:27:50 -0400 From: Sean Paul To: Lyude Paul Cc: dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, Juston Li , Imre Deak , Ville =?iso-8859-1?Q?Syrj=E4l=E4?= , Harry Wentland , Daniel Vetter , Maarten Lankhorst , Maxime Ripard , Sean Paul , David Airlie , Daniel Vetter , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 16/27] drm/dp_mst: Refactor pdt setup/teardown, add more locking Message-ID: <20190925192750.GH218215@art_vandelay> References: <20190903204645.25487-1-lyude@redhat.com> <20190903204645.25487-17-lyude@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190903204645.25487-17-lyude@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 03, 2019 at 04:45:54PM -0400, Lyude Paul wrote: > Since we're going to be implementing suspend/resume reprobing very soon, > we need to make sure we are extra careful to ensure that our locking > actually protects the topology state where we expect it to. Turns out > this isn't the case with drm_dp_port_setup_pdt() and > drm_dp_port_teardown_pdt(), both of which change port->mstb without > grabbing &mgr->lock. > > Additionally, since most callers of these functions are just using it to > teardown the port's previous PDT and setup a new one we can simplify > things a bit and combine drm_dp_port_setup_pdt() and > drm_dp_port_teardown_pdt() into a single function: > drm_dp_port_set_pdt(). This function also handles actually ensuring that > we grab the correct locks when we need to modify port->mstb. > > Cc: Juston Li > Cc: Imre Deak > Cc: Ville Syrjälä > Cc: Harry Wentland > Cc: Daniel Vetter > Signed-off-by: Lyude Paul > --- > drivers/gpu/drm/drm_dp_mst_topology.c | 181 +++++++++++++++----------- > include/drm/drm_dp_mst_helper.h | 6 +- > 2 files changed, 110 insertions(+), 77 deletions(-) > > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c > index d1610434a0cb..9944ef2ce885 100644 > --- a/drivers/gpu/drm/drm_dp_mst_topology.c > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c > @@ -1487,24 +1487,6 @@ drm_dp_mst_topology_put_mstb(struct drm_dp_mst_branch *mstb) > kref_put(&mstb->topology_kref, drm_dp_destroy_mst_branch_device); > } > > -static void drm_dp_port_teardown_pdt(struct drm_dp_mst_port *port, int old_pdt) > -{ > - struct drm_dp_mst_branch *mstb; > - > - switch (old_pdt) { > - case DP_PEER_DEVICE_DP_LEGACY_CONV: > - case DP_PEER_DEVICE_SST_SINK: > - /* remove i2c over sideband */ > - drm_dp_mst_unregister_i2c_bus(&port->aux); > - break; > - case DP_PEER_DEVICE_MST_BRANCHING: > - mstb = port->mstb; > - port->mstb = NULL; > - drm_dp_mst_topology_put_mstb(mstb); > - break; > - } > -} > - > static void drm_dp_destroy_port(struct kref *kref) > { > struct drm_dp_mst_port *port = > @@ -1714,38 +1696,79 @@ static u8 drm_dp_calculate_rad(struct drm_dp_mst_port *port, > return parent_lct + 1; > } > > -/* > - * return sends link address for new mstb > - */ > -static bool drm_dp_port_setup_pdt(struct drm_dp_mst_port *port) > +static int drm_dp_port_set_pdt(struct drm_dp_mst_port *port, u8 new_pdt) > { > - int ret; > - u8 rad[6], lct; > - bool send_link = false; > + struct drm_dp_mst_topology_mgr *mgr = port->mgr; > + struct drm_dp_mst_branch *mstb; > + u8 rad[8], lct; > + int ret = 0; > + > + if (port->pdt == new_pdt) Shouldn't we also ensure that access to port->pdt is also locked? Sean > + return 0; > + > + /* Teardown the old pdt, if there is one */ > + switch (port->pdt) { > + case DP_PEER_DEVICE_DP_LEGACY_CONV: > + case DP_PEER_DEVICE_SST_SINK: > + /* > + * If the new PDT would also have an i2c bus, don't bother > + * with reregistering it > + */ > + if (new_pdt == DP_PEER_DEVICE_DP_LEGACY_CONV || > + new_pdt == DP_PEER_DEVICE_SST_SINK) { > + port->pdt = new_pdt; > + return 0; > + } > + > + /* remove i2c over sideband */ > + drm_dp_mst_unregister_i2c_bus(&port->aux); > + break; > + case DP_PEER_DEVICE_MST_BRANCHING: > + mutex_lock(&mgr->lock); > + drm_dp_mst_topology_put_mstb(port->mstb); > + port->mstb = NULL; > + mutex_unlock(&mgr->lock); > + break; > + } > + > + port->pdt = new_pdt; > switch (port->pdt) { > case DP_PEER_DEVICE_DP_LEGACY_CONV: > case DP_PEER_DEVICE_SST_SINK: > /* add i2c over sideband */ > ret = drm_dp_mst_register_i2c_bus(&port->aux); > break; > + > case DP_PEER_DEVICE_MST_BRANCHING: > lct = drm_dp_calculate_rad(port, rad); > + mstb = drm_dp_add_mst_branch_device(lct, rad); > + if (!mstb) { > + ret = -ENOMEM; > + DRM_ERROR("Failed to create MSTB for port %p", port); > + goto out; > + } > > - port->mstb = drm_dp_add_mst_branch_device(lct, rad); > - if (port->mstb) { > - port->mstb->mgr = port->mgr; > - port->mstb->port_parent = port; > - /* > - * Make sure this port's memory allocation stays > - * around until its child MSTB releases it > - */ > - drm_dp_mst_get_port_malloc(port); > + mutex_lock(&mgr->lock); > + port->mstb = mstb; > + mstb->mgr = port->mgr; > + mstb->port_parent = port; > > - send_link = true; > - } > + /* > + * Make sure this port's memory allocation stays > + * around until its child MSTB releases it > + */ > + drm_dp_mst_get_port_malloc(port); > + mutex_unlock(&mgr->lock); > + > + /* And make sure we send a link address for this */ > + ret = 1; > break; > } > - return send_link; > + > +out: > + if (ret < 0) > + port->pdt = DP_PEER_DEVICE_NONE; > + return ret; > } > > /** > @@ -1881,10 +1904,9 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb, > struct drm_device *dev, > struct drm_dp_link_addr_reply_port *port_msg) > { > + struct drm_dp_mst_topology_mgr *mgr = mstb->mgr; > struct drm_dp_mst_port *port; > - bool ret; > bool created = false; > - int old_pdt = 0; > int old_ddps = 0; > > port = drm_dp_get_port(mstb, port_msg->port_number); > @@ -1896,7 +1918,7 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb, > kref_init(&port->malloc_kref); > port->parent = mstb; > port->port_num = port_msg->port_number; > - port->mgr = mstb->mgr; > + port->mgr = mgr; > port->aux.name = "DPMST"; > port->aux.dev = dev->dev; > port->aux.is_remote = true; > @@ -1909,11 +1931,9 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb, > > created = true; > } else { > - old_pdt = port->pdt; > old_ddps = port->ddps; > } > > - port->pdt = port_msg->peer_device_type; > port->input = port_msg->input_port; > port->mcs = port_msg->mcs; > port->ddps = port_msg->ddps; > @@ -1925,29 +1945,33 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb, > /* manage mstb port lists with mgr lock - take a reference > for this list */ > if (created) { > - mutex_lock(&mstb->mgr->lock); > + mutex_lock(&mgr->lock); > drm_dp_mst_topology_get_port(port); > list_add(&port->next, &mstb->ports); > - mutex_unlock(&mstb->mgr->lock); > + mutex_unlock(&mgr->lock); > } > > if (old_ddps != port->ddps) { > if (port->ddps) { > if (!port->input) { > - drm_dp_send_enum_path_resources(mstb->mgr, > - mstb, port); > + drm_dp_send_enum_path_resources(mgr, mstb, > + port); > } > } else { > port->available_pbn = 0; > } > } > > - if (old_pdt != port->pdt && !port->input) { > - drm_dp_port_teardown_pdt(port, old_pdt); > - > - ret = drm_dp_port_setup_pdt(port); > - if (ret == true) > - drm_dp_send_link_address(mstb->mgr, port->mstb); > + if (!port->input) { > + int ret = drm_dp_port_set_pdt(port, > + port_msg->peer_device_type); > + if (ret == 1) { > + drm_dp_send_link_address(mgr, port->mstb); > + } else if (ret < 0) { > + DRM_ERROR("Failed to change PDT on port %p: %d\n", > + port, ret); > + goto fail; > + } > } > > if (created && !port->input) { > @@ -1955,18 +1979,11 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb, > > build_mst_prop_path(mstb, port->port_num, proppath, > sizeof(proppath)); > - port->connector = (*mstb->mgr->cbs->add_connector)(mstb->mgr, > - port, > - proppath); > - if (!port->connector) { > - /* remove it from the port list */ > - mutex_lock(&mstb->mgr->lock); > - list_del(&port->next); > - mutex_unlock(&mstb->mgr->lock); > - /* drop port list reference */ > - drm_dp_mst_topology_put_port(port); > - goto out; > - } > + port->connector = (*mgr->cbs->add_connector)(mgr, port, > + proppath); > + if (!port->connector) > + goto fail; > + > if ((port->pdt == DP_PEER_DEVICE_DP_LEGACY_CONV || > port->pdt == DP_PEER_DEVICE_SST_SINK) && > port->port_num >= DP_MST_LOGICAL_PORT_0) { > @@ -1974,28 +1991,38 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb, > &port->aux.ddc); > drm_connector_set_tile_property(port->connector); > } > - (*mstb->mgr->cbs->register_connector)(port->connector); > + > + (*mgr->cbs->register_connector)(port->connector); > } > > -out: > /* put reference to this port */ > drm_dp_mst_topology_put_port(port); > + return; > + > +fail: > + /* Remove it from the port list */ > + mutex_lock(&mgr->lock); > + list_del(&port->next); > + mutex_unlock(&mgr->lock); > + > + /* Drop the port list reference */ > + drm_dp_mst_topology_put_port(port); > + /* And now drop our reference */ > + drm_dp_mst_topology_put_port(port); > } > > static void drm_dp_update_port(struct drm_dp_mst_branch *mstb, > struct drm_dp_connection_status_notify *conn_stat) > { > struct drm_dp_mst_port *port; > - int old_pdt; > int old_ddps; > bool dowork = false; > + > port = drm_dp_get_port(mstb, conn_stat->port_number); > if (!port) > return; > > old_ddps = port->ddps; > - old_pdt = port->pdt; > - port->pdt = conn_stat->peer_device_type; > port->mcs = conn_stat->message_capability_status; > port->ldps = conn_stat->legacy_device_plug_status; > port->ddps = conn_stat->displayport_device_plug_status; > @@ -2007,11 +2034,17 @@ static void drm_dp_update_port(struct drm_dp_mst_branch *mstb, > port->available_pbn = 0; > } > } > - if (old_pdt != port->pdt && !port->input) { > - drm_dp_port_teardown_pdt(port, old_pdt); > > - if (drm_dp_port_setup_pdt(port)) > + if (!port->input) { > + int ret = drm_dp_port_set_pdt(port, > + conn_stat->peer_device_type); > + if (ret == 1) { > dowork = true; > + } else if (ret < 0) { > + DRM_ERROR("Failed to change PDT for port %p: %d\n", > + port, ret); > + dowork = false; > + } > } > > drm_dp_mst_topology_put_port(port); > @@ -4003,9 +4036,7 @@ drm_dp_delayed_destroy_port(struct drm_dp_mst_port *port) > if (port->connector) > port->mgr->cbs->destroy_connector(port->mgr, port->connector); > > - drm_dp_port_teardown_pdt(port, port->pdt); > - port->pdt = DP_PEER_DEVICE_NONE; > - > + drm_dp_port_set_pdt(port, DP_PEER_DEVICE_NONE); > drm_dp_mst_put_port_malloc(port); > } > > diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h > index 5423a8adda78..f253ee43e9d9 100644 > --- a/include/drm/drm_dp_mst_helper.h > +++ b/include/drm/drm_dp_mst_helper.h > @@ -55,8 +55,10 @@ struct drm_dp_vcpi { > * @num_sdp_stream_sinks: Number of stream sinks > * @available_pbn: Available bandwidth for this port. > * @next: link to next port on this branch device > - * @mstb: branch device attach below this port > - * @aux: i2c aux transport to talk to device connected to this port. > + * @mstb: branch device on this port, protected by > + * &drm_dp_mst_topology_mgr.lock > + * @aux: i2c aux transport to talk to device connected to this port, protected > + * by &drm_dp_mst_topology_mgr.lock > * @parent: branch device parent of this port > * @vcpi: Virtual Channel Payload info for this port. > * @connector: DRM connector this port is connected to. > -- > 2.21.0 > -- Sean Paul, Software Engineer, Google / Chromium OS