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,URIBL_BLOCKED,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 ACE1EC4360C for ; Fri, 27 Sep 2019 13:30:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 64BE4206B7 for ; Fri, 27 Sep 2019 13:30:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=poorly.run header.i=@poorly.run header.b="PJ/lz00q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727450AbfI0NaP (ORCPT ); Fri, 27 Sep 2019 09:30:15 -0400 Received: from mail-yw1-f67.google.com ([209.85.161.67]:41705 "EHLO mail-yw1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725992AbfI0NaP (ORCPT ); Fri, 27 Sep 2019 09:30:15 -0400 Received: by mail-yw1-f67.google.com with SMTP id 129so884698ywb.8 for ; Fri, 27 Sep 2019 06:30:14 -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=hhaOA35aksrllBwVEVKU+X3E6wwjQjTWsM2RflZ/t40=; b=PJ/lz00qRN9N+2/54/FM6u9G4s2lbHbVFn1VR0FhpJL3kPY3lOIkAzlhMug3ea9WYB UkoWO6UjC5N7SWJh7ooTk21s5xMlsUYFAY60MlUbf+40jQNgmsGE35YgGOxPUpeysF+n 7eaJpty5wZcB6JgDRZd9Pu4kzcp/s3TiimENipXOCKPe8H8LteIE9DwIBX4Jkr+rzy2K ceZfE2AIuZGkJbz98ZQ/B6pVKE3c6WI1hdGWu8seGD5nzpp8oR6J46wAe3D/Bwa9i0LP lyh7lVGfaHHDZksPomEHSF9Be1Mx/Qs4Spxnur7BtFq6niI6RQ00fCeUdlbJ4Z7qk5Iq OPtA== 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=hhaOA35aksrllBwVEVKU+X3E6wwjQjTWsM2RflZ/t40=; b=KJLBEZo3X5g6d+WqiF06Qu3x7ohEYwlsgH7pTh40PhKoG3GVx9m/wtjgX5CtPE1vq1 tCdl+5uWKqiOHsaRc2ktydAaG/Divule76Lh3i0nslUK0SHwdSGStydRa8dm/ujd2TyA RidW+r9Yxz5/wzSupOZPRrtK5L99D7ser8es1F3TAUE8ntEEegigLerp2hh/Oawb8rFz Y3ux0KVslLoL8lRUOVoSRlMr77ipxBChgq1lRIa0BIcx7QwHOaD1N5MIVwx42/6mU/jp ubSHjAbEpvNO4GM56At5Z/mMlhQRonb3mYWEQwBGa/5fIbDPWDC3lYviW4FUUP9lGi/Z 7ilw== X-Gm-Message-State: APjAAAWnCjAVk6hKUcFX2BTJ8K6CQv+7sEmE1eEC+oNmlA260DG81ROy H/yjmZwHwi0n6NQNYu4bChFLbA== X-Google-Smtp-Source: APXvYqxmvKQo4gMLQL97D+Fl2OfhONdeyjwXGGcZeg0We7Htghg35MF90vz65Iulvvh81bUB6a9bkg== X-Received: by 2002:a81:6743:: with SMTP id b64mr2828589ywc.302.1569591013892; Fri, 27 Sep 2019 06:30:13 -0700 (PDT) Received: from localhost ([2620:0:1013:11:89c6:2139:5435:371d]) by smtp.gmail.com with ESMTPSA id o135sm611489ywo.75.2019.09.27.06.30.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Sep 2019 06:30:12 -0700 (PDT) Date: Fri, 27 Sep 2019 09:30:11 -0400 From: Sean Paul To: Lyude Paul Cc: Sean Paul , 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 , 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: <20190927133011.GP218215@art_vandelay> References: <20190903204645.25487-1-lyude@redhat.com> <20190903204645.25487-17-lyude@redhat.com> <20190925192750.GH218215@art_vandelay> <581dc77ab09314ac8d7c4cd7dc3efee5d4663a97.camel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <581dc77ab09314ac8d7c4cd7dc3efee5d4663a97.camel@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 Wed, Sep 25, 2019 at 05:00:00PM -0400, Lyude Paul wrote: > On Wed, 2019-09-25 at 15:27 -0400, Sean Paul wrote: > > 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? > > > > It's specifically port->mstb that needs to be protected under lock. We don't > use port->pdt for traversing the topology at all, so keeping it under > connection_mutex is sufficient. > I hadn't gotten to the connection_mutex patch yet when I made that comment :) Reviewed-by: Sean Paul > > 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 > > > > -- > Cheers, > Lyude Paul > -- Sean Paul, Software Engineer, Google / Chromium OS