From: Shuah Khan <shuahkh@osg.samsung.com> To: mchehab@osg.samsung.com, tiwai@suse.com, clemens@ladisch.de, hans.verkuil@cisco.com, laurent.pinchart@ideasonboard.com, sakari.ailus@linux.intel.com, javier@osg.samsung.com Cc: Shuah Khan <shuahkh@osg.samsung.com>, pawel@osciak.com, m.szyprowski@samsung.com, kyungmin.park@samsung.com, perex@perex.cz, arnd@arndb.de, dan.carpenter@oracle.com, tvboxspy@gmail.com, crope@iki.fi, ruchandani.tina@gmail.com, corbet@lwn.net, chehabrafael@gmail.com, k.kozlowski@samsung.com, stefanr@s5r6.in-berlin.de, inki.dae@samsung.com, jh1009.sung@samsung.com, elfring@users.sourceforge.net, prabhakar.csengg@gmail.com, sw0312.kim@samsung.com, p.zabel@pengutronix.de, ricardo.ribalda@gmail.com, labbott@fedoraproject.org, pierre-louis.bossart@linux.intel.com, ricard.wanderlof@axis.com, julian@jusst.de, takamichiho@gmail.com, dominic.sacre@gmx.de, misterpib@gmail.com, daniel@zonque.org, gtmkramer@xs4all.nl, normalperson@yhbt.net, joe@oampo.co.uk, linuxbugs@vittgam.net, johan@oljud.se, klock.android@gmail.com, nenggun.kim@samsung.com, j.anaszewski@samsung.com, geliangtang@163.com, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-api@vger.kernel.org, alsa-devel@alsa-project.org Subject: [PATCH v2 22/22] media: Ensure media device unregister is done only once Date: Wed, 3 Feb 2016 21:03:54 -0700 [thread overview] Message-ID: <9c22d4395f92102051383110cae9de09494d7257.1454557589.git.shuahkh@osg.samsung.com> (raw) In-Reply-To: <cover.1454557589.git.shuahkh@osg.samsung.com> In-Reply-To: <cover.1454557589.git.shuahkh@osg.samsung.com> media_device_unregister() checks if the media device is registered or not as the first step. However, the MEDIA_FLAG_REGISTERED bit doesn't get cleared until the end leaving a large window for two drivers to attempt media device unregister. The above leads to general protection faults when device is removed. Fix the problem with two phase media device unregister. Add a new interface media_devnode_start_unregister() to clear the MEDIA_FLAG_REGISTERED bit. Change media_device_unregister() call this interface to mark the start of unregister. This will ensure that media device unregister is done only once. Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com> --- drivers/media/media-device.c | 12 ++++++------ drivers/media/media-devnode.c | 15 ++++++++++----- include/media/media-devnode.h | 17 +++++++++++++++++ 3 files changed, 33 insertions(+), 11 deletions(-) diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c index 1f5d67e..584d46e 100644 --- a/drivers/media/media-device.c +++ b/drivers/media/media-device.c @@ -747,17 +747,17 @@ void media_device_unregister(struct media_device *mdev) struct media_entity *next; struct media_interface *intf, *tmp_intf; struct media_entity_notify *notify, *nextp; + int ret; if (mdev == NULL) return; - spin_lock(&mdev->lock); - - /* Check if mdev was ever registered at all */ - if (!media_devnode_is_registered(&mdev->devnode)) { - spin_unlock(&mdev->lock); + /* Start unregister - continue if necessary */ + ret = media_devnode_start_unregister(&mdev->devnode); + if (ret) return; - } + + spin_lock(&mdev->lock); /* Remove all entities from the media device */ list_for_each_entry_safe(entity, next, &mdev->entities, graph_obj.list) diff --git a/drivers/media/media-devnode.c b/drivers/media/media-devnode.c index 29409f4..c27f9e7 100644 --- a/drivers/media/media-devnode.c +++ b/drivers/media/media-devnode.c @@ -272,15 +272,20 @@ error: return ret; } -void media_devnode_unregister(struct media_devnode *mdev) +int __must_check media_devnode_start_unregister(struct media_devnode *mdev) { - /* Check if mdev was ever registered at all */ - if (!media_devnode_is_registered(mdev)) - return; - mutex_lock(&media_devnode_lock); + if (!media_devnode_is_registered(mdev)) { + mutex_unlock(&media_devnode_lock); + return -EINVAL; + } clear_bit(MEDIA_FLAG_REGISTERED, &mdev->flags); mutex_unlock(&media_devnode_lock); + return 0; +} + +void media_devnode_unregister(struct media_devnode *mdev) +{ device_unregister(&mdev->dev); } diff --git a/include/media/media-devnode.h b/include/media/media-devnode.h index fe42f08..6f08677 100644 --- a/include/media/media-devnode.h +++ b/include/media/media-devnode.h @@ -120,6 +120,23 @@ int __must_check media_devnode_register(struct media_devnode *mdev, struct module *owner); /** + * media_devnode_start_unregister - start unregister on a media device node + * @mdev: the device node to start unregister + * + * This clears the MEDIA_FLAG_REGISTERED bit to indicate that unregister + * is in progress. + * + * This function can safely be called if the device node has never been + * registered or has already been unregistered. + * + * Zero is returned on success. + * + * -EINVAL is returned if the device node has never been + * registered or has already been unregistered. + */ +int __must_check media_devnode_start_unregister(struct media_devnode *mdev); + +/** * media_devnode_unregister - unregister a media device node * @mdev: the device node to unregister * -- 2.5.0
WARNING: multiple messages have this Message-ID (diff)
From: Shuah Khan <shuahkh@osg.samsung.com> To: mchehab@osg.samsung.com, tiwai@suse.com, clemens@ladisch.de, hans.verkuil@cisco.com, laurent.pinchart@ideasonboard.com, sakari.ailus@linux.intel.com, javier@osg.samsung.com Cc: Shuah Khan <shuahkh@osg.samsung.com>, pawel@osciak.com, m.szyprowski@samsung.com, kyungmin.park@samsung.com, perex@perex.cz, arnd@arndb.de, dan.carpenter@oracle.com, tvboxspy@gmail.com, crope@iki.fi, ruchandani.tina@gmail.com, corbet@lwn.net, chehabrafael@gmail.com, k.kozlowski@samsung.com, stefanr@s5r6.in-berlin.de, inki.dae@samsung.com, jh1009.sung@samsung.com, elfring@users.sourceforge.net, prabhakar.csengg@gmail.com, sw0312.kim@samsung.com, p.zabel@pengutronix.de, ricardo.ribalda@gmail.com, labbott@fedoraproject.org, pierre-louis.bossart@linux.intel.com, ricard.wanderlof@axis.com, julian@jusst.de, takamichiho@gmail.com, dominic.sacre@gmx.de, misterpib@gmail.com, daniel@zonque.org, gtmkramer@xs4all.nl, normalperson@yhbt.net, joe@oampo.co.uk, linuxbugs@vittgam.net, johan@oljud.se, klock.android@gmail.com, nenggun.kim@samsung.com, j.anaszewski@samsung.com, geliangtang Subject: [PATCH v2 22/22] media: Ensure media device unregister is done only once Date: Wed, 3 Feb 2016 21:03:54 -0700 [thread overview] Message-ID: <9c22d4395f92102051383110cae9de09494d7257.1454557589.git.shuahkh@osg.samsung.com> (raw) In-Reply-To: <cover.1454557589.git.shuahkh@osg.samsung.com> In-Reply-To: <cover.1454557589.git.shuahkh@osg.samsung.com> media_device_unregister() checks if the media device is registered or not as the first step. However, the MEDIA_FLAG_REGISTERED bit doesn't get cleared until the end leaving a large window for two drivers to attempt media device unregister. The above leads to general protection faults when device is removed. Fix the problem with two phase media device unregister. Add a new interface media_devnode_start_unregister() to clear the MEDIA_FLAG_REGISTERED bit. Change media_device_unregister() call this interface to mark the start of unregister. This will ensure that media device unregister is done only once. Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com> --- drivers/media/media-device.c | 12 ++++++------ drivers/media/media-devnode.c | 15 ++++++++++----- include/media/media-devnode.h | 17 +++++++++++++++++ 3 files changed, 33 insertions(+), 11 deletions(-) diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c index 1f5d67e..584d46e 100644 --- a/drivers/media/media-device.c +++ b/drivers/media/media-device.c @@ -747,17 +747,17 @@ void media_device_unregister(struct media_device *mdev) struct media_entity *next; struct media_interface *intf, *tmp_intf; struct media_entity_notify *notify, *nextp; + int ret; if (mdev == NULL) return; - spin_lock(&mdev->lock); - - /* Check if mdev was ever registered at all */ - if (!media_devnode_is_registered(&mdev->devnode)) { - spin_unlock(&mdev->lock); + /* Start unregister - continue if necessary */ + ret = media_devnode_start_unregister(&mdev->devnode); + if (ret) return; - } + + spin_lock(&mdev->lock); /* Remove all entities from the media device */ list_for_each_entry_safe(entity, next, &mdev->entities, graph_obj.list) diff --git a/drivers/media/media-devnode.c b/drivers/media/media-devnode.c index 29409f4..c27f9e7 100644 --- a/drivers/media/media-devnode.c +++ b/drivers/media/media-devnode.c @@ -272,15 +272,20 @@ error: return ret; } -void media_devnode_unregister(struct media_devnode *mdev) +int __must_check media_devnode_start_unregister(struct media_devnode *mdev) { - /* Check if mdev was ever registered at all */ - if (!media_devnode_is_registered(mdev)) - return; - mutex_lock(&media_devnode_lock); + if (!media_devnode_is_registered(mdev)) { + mutex_unlock(&media_devnode_lock); + return -EINVAL; + } clear_bit(MEDIA_FLAG_REGISTERED, &mdev->flags); mutex_unlock(&media_devnode_lock); + return 0; +} + +void media_devnode_unregister(struct media_devnode *mdev) +{ device_unregister(&mdev->dev); } diff --git a/include/media/media-devnode.h b/include/media/media-devnode.h index fe42f08..6f08677 100644 --- a/include/media/media-devnode.h +++ b/include/media/media-devnode.h @@ -120,6 +120,23 @@ int __must_check media_devnode_register(struct media_devnode *mdev, struct module *owner); /** + * media_devnode_start_unregister - start unregister on a media device node + * @mdev: the device node to start unregister + * + * This clears the MEDIA_FLAG_REGISTERED bit to indicate that unregister + * is in progress. + * + * This function can safely be called if the device node has never been + * registered or has already been unregistered. + * + * Zero is returned on success. + * + * -EINVAL is returned if the device node has never been + * registered or has already been unregistered. + */ +int __must_check media_devnode_start_unregister(struct media_devnode *mdev); + +/** * media_devnode_unregister - unregister a media device node * @mdev: the device node to unregister * -- 2.5.0
next prev parent reply other threads:[~2016-02-04 4:04 UTC|newest] Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-02-04 4:03 [PATCH v2 00/22] Sharing media resources across ALSA and au0828 drivers Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 01/22] uapi/media.h: Declare interface types for ALSA Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 8:38 ` Mauro Carvalho Chehab 2016-02-04 8:38 ` Mauro Carvalho Chehab 2016-02-04 4:03 ` [PATCH v2 02/22] media: Add ALSA Media Controller function entities Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 8:40 ` Mauro Carvalho Chehab 2016-02-04 8:40 ` Mauro Carvalho Chehab 2016-02-04 4:03 ` [PATCH v2 03/22] media: Media Controller register/unregister entity_notify API Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 9:03 ` Mauro Carvalho Chehab 2016-02-04 9:03 ` Mauro Carvalho Chehab 2016-02-04 4:03 ` [PATCH v2 04/22] media: Media Controller enable/disable source handler API Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 05/22] media: Media Controller export non locking __media_entity_setup_link() Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 06/22] media: Media Controller non-locking __media_entity_pipeline_start/stop() Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 9:18 ` Mauro Carvalho Chehab 2016-02-04 9:18 ` Mauro Carvalho Chehab 2016-02-04 15:00 ` Shuah Khan 2016-02-04 15:00 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 07/22] media: v4l-core add enable/disable source common interfaces Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 6:29 ` kbuild test robot 2016-02-04 6:29 ` kbuild test robot 2016-02-04 9:25 ` Mauro Carvalho Chehab 2016-02-04 9:25 ` Mauro Carvalho Chehab 2016-02-04 4:03 ` [PATCH v2 08/22] media: Move au8522_media_pads enum to au8522.h from au8522_priv.h Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 09/22] media: au8522 change to create MC pad for ALSA Audio Out Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 10/22] media: Change v4l-core to check if source is free Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 11/22] media: dvb-frontend invoke enable/disable_source handlers Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 9:35 ` Mauro Carvalho Chehab 2016-02-04 9:35 ` Mauro Carvalho Chehab 2016-02-04 14:58 ` Shuah Khan 2016-02-04 14:58 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 12/22] media: au0828 video remove au0828_enable_analog_tuner() Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 9:37 ` Mauro Carvalho Chehab 2016-02-04 9:37 ` Mauro Carvalho Chehab 2016-02-04 14:49 ` Shuah Khan 2016-02-04 14:49 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 13/22] media: au0828 video change to use v4l_enable_media_source() Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 10:00 ` Mauro Carvalho Chehab 2016-02-04 10:00 ` Mauro Carvalho Chehab 2016-02-04 4:03 ` [PATCH v2 14/22] media: au0828 change to use Managed Media Controller API Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 10:05 ` Mauro Carvalho Chehab 2016-02-04 10:05 ` Mauro Carvalho Chehab 2016-02-04 10:08 ` Mauro Carvalho Chehab 2016-02-04 10:08 ` Mauro Carvalho Chehab 2016-02-04 4:03 ` [PATCH v2 15/22] media: au0828 handle media_init and media_register window Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 16/22] media: au0828 create tuner to decoder link in disabled state Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 17/22] media: au0828 disable tuner to demod link Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 18/22] media: au0828 Use au8522_media_pads enum for pad defines Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 19/22] media: au0828-core register entity_notify hook Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 4:03 ` [PATCH v2 20/22] media: au0828 add enable, disable source handlers Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 10:26 ` Mauro Carvalho Chehab 2016-02-04 10:26 ` Mauro Carvalho Chehab 2016-02-08 22:42 ` Shuah Khan 2016-02-08 22:42 ` Shuah Khan 2016-02-08 23:00 ` Shuah Khan 2016-02-08 23:00 ` Shuah Khan 2016-02-09 13:42 ` Mauro Carvalho Chehab 2016-02-09 13:42 ` Mauro Carvalho Chehab 2016-02-09 10:51 ` Mauro Carvalho Chehab 2016-02-09 10:51 ` Mauro Carvalho Chehab 2016-02-04 4:03 ` [PATCH v2 21/22] sound/usb: Use Media Controller API to share media resources Shuah Khan 2016-02-04 4:03 ` Shuah Khan 2016-02-04 10:36 ` Mauro Carvalho Chehab 2016-02-04 10:36 ` Mauro Carvalho Chehab 2016-02-04 10:46 ` Takashi Iwai 2016-02-04 10:46 ` Takashi Iwai 2016-02-07 11:25 ` kbuild test robot 2016-02-07 11:25 ` kbuild test robot 2016-02-04 4:03 ` Shuah Khan [this message] 2016-02-04 4:03 ` [PATCH v2 22/22] media: Ensure media device unregister is done only once Shuah Khan 2016-02-04 10:40 ` Mauro Carvalho Chehab 2016-02-04 10:40 ` Mauro Carvalho Chehab 2016-02-04 10:54 ` [PATCH v2 00/22] Sharing media resources across ALSA and au0828 drivers Mauro Carvalho Chehab 2016-02-04 10:54 ` Mauro Carvalho Chehab
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