From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752490AbeEOG2B (ORCPT ); Tue, 15 May 2018 02:28:01 -0400 Received: from lb1-smtp-cloud9.xs4all.net ([194.109.24.22]:59963 "EHLO lb1-smtp-cloud9.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752408AbeEOG16 (ORCPT ); Tue, 15 May 2018 02:27:58 -0400 Subject: Re: [RFC PATCH 2/5] media: cec-notifier: Get notifier by device and connector name To: Neil Armstrong , airlied@linux.ie, hans.verkuil@cisco.com, lee.jones@linaro.org, olof@lixom.net, seanpaul@google.com Cc: sadolfsson@google.com, felixe@google.com, bleung@google.com, darekm@google.com, marcheu@chromium.org, fparent@baylibre.com, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <1526337639-3568-1-git-send-email-narmstrong@baylibre.com> <1526337639-3568-3-git-send-email-narmstrong@baylibre.com> From: Hans Verkuil Message-ID: Date: Tue, 15 May 2018 08:27:49 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <1526337639-3568-3-git-send-email-narmstrong@baylibre.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-CMAE-Envelope: MS4wfLh993B099RGQcW93I9v6jp8ducIPC5nua+zaf5U9EsNqByFc1NX+d1wi+SY56NiF/FoCB9v2MlnEnZ+e9hYw4j3qW0e+FWoCf/nPHoCr1uzEtnXdd+O CkLAJBO5bOpE2N3gO6H3tTrqH/I3L8wC+wiE+V8cQ2wsN+8ngqBLhvbcWdf74XOnksBnO9XBezxbRgzQCSD3n5ePishgZMTO8UjDZAnO1DDvjnb31XEtZ3HB 3e/tUqPgcF6Ci81emLRaY79f6tpVby1SFimsApRelRooPDKxhmvsZ33BUJFUWx65ZCBjhtpI4sUfDrd6lLl2xC7aSTWqZg2+0kG8Quisjj8PIwHdqBWWUj+b TIK4xVQoE3WpRvBOI6fuopaowxqGUNoRVal2/7ai/oGYP6i64zBFy2Fj59IoKdGk0ga9pM3BCx13KlgyFIw2XevF/AjX2GcOIU425hEF9L5DUoOjB1zBughz gevH89rRvN7nqwDmT1HxFxrpRbQc2txYOG29KLAkEy5z0mZlWe6sH+7o6M2MG1p6+koE2n6K7CWK/n3y1Z8huRlMDLFKybPKXn9rRy6x2sbaAXiJzdCJjIE/ 8lMDmwT8jw26Pyqevh4WN2c9wZ3LAMxWR8W8xSzvyeW9WsVqsSSy5TePbfHx/rQ76lob3eXN9ZqOTydyrEHdZ1vdZlPbkZHyVP4Fn2W8NhJX+6kk0+HtRv7z G6bcV7+8fYc= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Neil, Thanks for this patch series! Some comments below: On 05/15/2018 12:40 AM, Neil Armstrong wrote: > In non device-tree world, we can need to get the notifier by the driver > name directly and eventually defer probe if not yet created. > > This patch adds a variant of the get function by using the device name > instead and will not create a notifier if not yet created. > > But the i915 driver exposes at least 2 HDMI connectors, this patch also > adds the possibility to add a connector name tied to the notifier device > to form a tuple and associate different CEC controllers for each HDMI > connectors. > > Signed-off-by: Neil Armstrong > --- > drivers/media/cec/cec-notifier.c | 30 ++++++++++++++++++++++++--- > include/media/cec-notifier.h | 44 ++++++++++++++++++++++++++++++++++++++-- > 2 files changed, 69 insertions(+), 5 deletions(-) > > diff --git a/drivers/media/cec/cec-notifier.c b/drivers/media/cec/cec-notifier.c > index 16dffa0..716070a 100644 > --- a/drivers/media/cec/cec-notifier.c > +++ b/drivers/media/cec/cec-notifier.c > @@ -21,6 +21,7 @@ struct cec_notifier { > struct list_head head; > struct kref kref; > struct device *dev; > + const char *conn; > struct cec_adapter *cec_adap; > void (*callback)(struct cec_adapter *adap, u16 pa); > > @@ -30,13 +31,34 @@ struct cec_notifier { > static LIST_HEAD(cec_notifiers); > static DEFINE_MUTEX(cec_notifiers_lock); > > -struct cec_notifier *cec_notifier_get(struct device *dev) > +struct cec_notifier *cec_notifier_get_byname(const char *name, > + const char *conn) > { > struct cec_notifier *n; > > mutex_lock(&cec_notifiers_lock); > list_for_each_entry(n, &cec_notifiers, head) { > - if (n->dev == dev) { > + if (!strcmp(dev_name(n->dev), name) && > + (!conn || !strcmp(n->conn, conn))) { > + kref_get(&n->kref); > + mutex_unlock(&cec_notifiers_lock); > + return n; > + } > + } > + mutex_unlock(&cec_notifiers_lock); > + > + return NULL; This doesn't seem right. For one it doesn't act like the other cec_notifier_get* functions in that it doesn't make a new notifier if it wasn't found yet in the list. For another, I think this function shouldn't be here at all. How about calling bus_find_device_by_name(), then use cec_notifier_get_conn()? > +} > +EXPORT_SYMBOL_GPL(cec_notifier_get_byname); > + > +struct cec_notifier *cec_notifier_get_conn(struct device *dev, const char *conn) > +{ > + struct cec_notifier *n; > + > + mutex_lock(&cec_notifiers_lock); > + list_for_each_entry(n, &cec_notifiers, head) { > + if (n->dev == dev && > + (!conn || !strcmp(n->conn, conn))) { > kref_get(&n->kref); > mutex_unlock(&cec_notifiers_lock); > return n; > @@ -46,6 +68,8 @@ struct cec_notifier *cec_notifier_get(struct device *dev) > if (!n) > goto unlock; > n->dev = dev; > + if (conn) > + n->conn = devm_kstrdup(dev, conn, GFP_KERNEL); The use of devm_kstrdup worries me. The problem is that when the 'dev' device is removed, this memory is also automatically freed. But the notifier might still have a reference through the CEC driver, so you end up with a n->conn pointer that points to freed memory. I think it is better to just use kstrdup and kfree it when the last notifier reference is released. > n->phys_addr = CEC_PHYS_ADDR_INVALID; > mutex_init(&n->lock); > kref_init(&n->kref); > @@ -54,7 +78,7 @@ struct cec_notifier *cec_notifier_get(struct device *dev) > mutex_unlock(&cec_notifiers_lock); > return n; > } > -EXPORT_SYMBOL_GPL(cec_notifier_get); > +EXPORT_SYMBOL_GPL(cec_notifier_get_conn); > > static void cec_notifier_release(struct kref *kref) > { > diff --git a/include/media/cec-notifier.h b/include/media/cec-notifier.h > index cf0add7..70f2974 100644 > --- a/include/media/cec-notifier.h > +++ b/include/media/cec-notifier.h > @@ -20,6 +20,37 @@ struct cec_notifier; > #if IS_REACHABLE(CONFIG_CEC_CORE) && IS_ENABLED(CONFIG_CEC_NOTIFIER) > > /** > + * cec_notifier_get_byname - find a cec_notifier for the given device name > + * and connector tuple. > + * @name: device name that sends the events. > + * @conn: the connector name from which the event occurs > + * > + * If a notifier for device @name exists, then increase the refcount and > + * return that notifier. > + * > + * If it doesn't exist, return NULL > + */ > +struct cec_notifier *cec_notifier_get_byname(const char *name, > + const char *conn); > + > +/** > + * cec_notifier_get_conn - find or create a new cec_notifier for the given > + * device and connector tuple. > + * @dev: device that sends the events. > + * @conn: the connector name from which the event occurs > + * > + * If a notifier for device @dev already exists, then increase the refcount > + * and return that notifier. > + * > + * If it doesn't exist, then allocate a new notifier struct and return a > + * pointer to that new struct. > + * > + * Return NULL if the memory could not be allocated. > + */ > +struct cec_notifier *cec_notifier_get_conn(struct device *dev, > + const char *conn); > + > +/** > * cec_notifier_get - find or create a new cec_notifier for the given device. > * @dev: device that sends the events. > * > @@ -31,7 +62,10 @@ struct cec_notifier; > * > * Return NULL if the memory could not be allocated. > */ > -struct cec_notifier *cec_notifier_get(struct device *dev); > +static inline struct cec_notifier *cec_notifier_get(struct device *dev) > +{ > + return cec_notifier_get_conn(dev, NULL); > +} > > /** > * cec_notifier_put - decrease refcount and delete when the refcount reaches 0. > @@ -85,12 +119,18 @@ void cec_register_cec_notifier(struct cec_adapter *adap, > struct cec_notifier *notifier); > > #else > -static inline struct cec_notifier *cec_notifier_get(struct device *dev) > +static inline struct cec_notifier *cec_notifier_get_conn(struct device *dev, > + const char *conn) > { > /* A non-NULL pointer is expected on success */ > return (struct cec_notifier *)0xdeadfeed; > } > > +static inline struct cec_notifier *cec_notifier_get(struct device *dev) > +{ > + return cec_notifier_get_conn(dev, NULL); > +} > + > static inline void cec_notifier_put(struct cec_notifier *n) > { > } > Regards, Hans