Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751768AbdG1IXV (ORCPT ); Fri, 28 Jul 2017 04:23:21 -0400 Received: from muru.com ([72.249.23.125]:56232 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751746AbdG1IXU (ORCPT ); Fri, 28 Jul 2017 04:23:20 -0400 Date: Fri, 28 Jul 2017 01:23:15 -0700 From: Tony Lindgren To: Rob Herring Cc: Frank Rowand , Grant Likely , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , linux-omap , Mark Brown , Takashi Iwai , Kuninori Morimoto , Linux-ALSA Subject: Re: [PATCH] device property: Fix usecount for of_graph_get_port_parent() Message-ID: <20170728082315.GL10026@atomide.com> References: <20170727094405.19778-1-tony@atomide.com> <20170728060127.GH10026@atomide.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170728060127.GH10026@atomide.com> User-Agent: Mutt/1.8.3 (2017-05-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7950 Lines: 255 * Tony Lindgren [170727 23:02]: > * Rob Herring [170727 15:19]: > > On Thu, Jul 27, 2017 at 4:44 AM, Tony Lindgren wrote: > > > --- a/drivers/of/property.c > > > +++ b/drivers/of/property.c > > > @@ -708,6 +708,15 @@ struct device_node *of_graph_get_port_parent(struct device_node *node) > > > { > > > unsigned int depth; > > > > > > + if (!node) > > > + return NULL; > > > + > > > + /* > > > + * Preserve usecount for passed in node as of_get_next_parent() > > > + * will do of_node_put() on it. > > > + */ > > > + of_node_get(node); > > > > I think this messes up of_graph_get_remote_port_parent(). First it > > calls of_graph_get_remote_endpoint which returns the endpoint node > > with ref count incremented. Then you are incrementing it again here. > > Hmm OK looks like I missed that one. If we want to have > of_graph_get_port_parent not trash the node passed to it, we should > just change things there too: Found few more things to fix with git grep -C20 of_graph_get_port_parent, below is v2. Can you all prese review again and do some testing. I also fixed up audio-graph-scu-card but can't test that one. Regards, Tony 8< ------ >From tony Mon Sep 17 00:00:00 2001 From: Tony Lindgren Date: Thu, 27 Jul 2017 01:30:16 -0700 Subject: [PATCHv2] device property: Fix usecount for of_graph_get_port_parent() Fix inconsistent use of of_graph_get_port_parent() where asoc_simple_card_parse_graph_dai() does of_node_get() before calling it while other callers do not. We can fix this by not trashing the node passed to of_graph_get_port_parent(). Let's also make sure the callers have correct refcounts and remove related incorrect of_node_put() calls for of_for_each_phandle as that's done by of_phandle_iterator_next() except when we break out of the loop early. Let's fix both issues with a single patch to avoid kobject refcounts getting messed up more if two patches are merged separately. Otherwise strange issues can happen caused by memory corruption caused by too many kobject_del() calls such as: BUG: sleeping function called from invalid context at kernel/locking/mutex.c:747 ... (___might_sleep) (__mutex_lock) (mutex_lock_nested) (kernfs_remove) (kobject_del) (kobject_put) (of_get_next_parent) (of_graph_get_port_parent) (asoc_simple_card_parse_graph_dai [snd_soc_simple_card_utils]) (asoc_graph_card_probe [snd_soc_audio_graph_card]) Fixes: 0ef472a973eb ("of_graph: add of_graph_get_port_parent()") Fixes: 2692c1c63c29 ("ASoC: add audio-graph-card support") Fixes: 1689333f8311 ("ASoC: simple-card-utils: add asoc_simple_card_parse_graph_dai()") Cc: Mark Brown Cc: Takashi Iwai Cc: Kuninori Morimoto Cc: alsa-devel@alsa-project.org Signed-off-by: Tony Lindgren --- drivers/of/property.c | 17 +++++++++++++++-- sound/soc/generic/audio-graph-card.c | 10 +++++----- sound/soc/generic/audio-graph-scu-card.c | 15 +++++++++------ sound/soc/generic/simple-card-utils.c | 8 +++----- sound/soc/soc-core.c | 2 ++ 5 files changed, 34 insertions(+), 18 deletions(-) diff --git a/drivers/of/property.c b/drivers/of/property.c --- a/drivers/of/property.c +++ b/drivers/of/property.c @@ -708,6 +708,15 @@ struct device_node *of_graph_get_port_parent(struct device_node *node) { unsigned int depth; + if (!node) + return NULL; + + /* + * Preserve usecount for passed in node as of_get_next_parent() + * will do of_node_put() on it. + */ + of_node_get(node); + /* Walk 3 levels up only if there is 'ports' node. */ for (depth = 3; depth && node; depth--) { node = of_get_next_parent(node); @@ -728,12 +737,16 @@ EXPORT_SYMBOL(of_graph_get_port_parent); struct device_node *of_graph_get_remote_port_parent( const struct device_node *node) { - struct device_node *np; + struct device_node *np, *pp; /* Get remote endpoint node. */ np = of_graph_get_remote_endpoint(node); - return of_graph_get_port_parent(np); + pp = of_graph_get_port_parent(np); + + of_node_put(np); + + return pp; } EXPORT_SYMBOL(of_graph_get_remote_port_parent); diff --git a/sound/soc/generic/audio-graph-card.c b/sound/soc/generic/audio-graph-card.c --- a/sound/soc/generic/audio-graph-card.c +++ b/sound/soc/generic/audio-graph-card.c @@ -224,9 +224,11 @@ static int asoc_graph_card_parse_of(struct graph_card_data *priv) of_for_each_phandle(&it, rc, node, "dais", NULL, 0) { ret = asoc_graph_card_dai_link_of(it.node, priv, idx++); - of_node_put(it.node); - if (ret < 0) + if (ret < 0) { + of_node_put(it.node); + return ret; + } } return asoc_simple_card_parse_card_name(card, NULL); @@ -239,10 +241,8 @@ static int asoc_graph_get_dais_count(struct device *dev) int count = 0; int rc; - of_for_each_phandle(&it, rc, node, "dais", NULL, 0) { + of_for_each_phandle(&it, rc, node, "dais", NULL, 0) count++; - of_node_put(it.node); - } return count; } diff --git a/sound/soc/generic/audio-graph-scu-card.c b/sound/soc/generic/audio-graph-scu-card.c --- a/sound/soc/generic/audio-graph-scu-card.c +++ b/sound/soc/generic/audio-graph-scu-card.c @@ -215,7 +215,6 @@ static int asoc_graph_card_parse_of(struct graph_card_data *priv) codec_ep = of_graph_get_remote_endpoint(cpu_ep); rcpu_ep = of_graph_get_remote_endpoint(codec_ep); - of_node_put(cpu_port); of_node_put(cpu_ep); of_node_put(codec_ep); of_node_put(rcpu_ep); @@ -232,8 +231,10 @@ static int asoc_graph_card_parse_of(struct graph_card_data *priv) ret = asoc_simple_card_parse_daifmt(dev, cpu_ep, codec_ep, NULL, &daifmt); - if (ret < 0) + if (ret < 0) { + of_node_put(cpu_port); goto parse_of_err; + } } dai_idx = 0; @@ -250,7 +251,6 @@ static int asoc_graph_card_parse_of(struct graph_card_data *priv) codec_ep = of_graph_get_remote_endpoint(cpu_ep); codec_port = of_graph_get_port_parent(codec_ep); - of_node_put(cpu_port); of_node_put(cpu_ep); of_node_put(codec_ep); of_node_put(codec_port); @@ -266,13 +266,17 @@ static int asoc_graph_card_parse_of(struct graph_card_data *priv) /* Back-End (= Codec) */ ret = asoc_graph_card_dai_link_of(codec_ep, priv, daifmt, dai_idx++, 0); - if (ret < 0) + if (ret < 0) { + of_node_put(cpu_port); goto parse_of_err; + } } else { /* Front-End (= CPU) */ ret = asoc_graph_card_dai_link_of(cpu_ep, priv, daifmt, dai_idx++, 1); - if (ret < 0) + if (ret < 0) { + of_node_put(cpu_port); goto parse_of_err; + } } } } @@ -306,7 +310,6 @@ static int asoc_graph_get_dais_count(struct device *dev) codec_ep = of_graph_get_remote_endpoint(cpu_ep); codec_port = of_graph_get_port_parent(codec_ep); - of_node_put(cpu_port); of_node_put(cpu_ep); of_node_put(codec_ep); of_node_put(codec_port); diff --git a/sound/soc/generic/simple-card-utils.c b/sound/soc/generic/simple-card-utils.c --- a/sound/soc/generic/simple-card-utils.c +++ b/sound/soc/generic/simple-card-utils.c @@ -263,6 +263,9 @@ static int asoc_simple_card_get_dai_id(struct device_node *ep) id = i; i++; } + + of_node_put(node); + if (id < 0) return -ENODEV; @@ -282,11 +285,6 @@ int asoc_simple_card_parse_graph_dai(struct device_node *ep, if (!dai_name) return 0; - /* - * of_graph_get_port_parent() will call - * of_node_put(). So, call of_node_get() here - */ - of_node_get(ep); node = of_graph_get_port_parent(ep); /* Get dai->name */ diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c --- a/sound/soc/soc-core.c +++ b/sound/soc/soc-core.c @@ -4113,6 +4113,8 @@ int snd_soc_get_dai_id(struct device_node *ep) } mutex_unlock(&client_mutex); + of_node_put(node); + return ret; } EXPORT_SYMBOL_GPL(snd_soc_get_dai_id); -- 2.13.2