linux-kernel - [PATCH 29/31] media: track media device unregister in progress

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <151cfbe0e59b3d5396951bdcc29666614575f5bc.1452105878.git.shuahkh@osg.samsung.com>
Date:	Wed,  6 Jan 2016 13:27:18 -0700
From:	Shuah Khan <shuahkh@....samsung.com>
To:	mchehab@....samsung.com, tiwai@...e.com, clemens@...isch.de,
	hans.verkuil@...co.com, laurent.pinchart@...asonboard.com,
	sakari.ailus@...ux.intel.com, javier@....samsung.com
Cc:	Shuah Khan <shuahkh@....samsung.com>, pawel@...iak.com,
	m.szyprowski@...sung.com, kyungmin.park@...sung.com,
	perex@...ex.cz, arnd@...db.de, dan.carpenter@...cle.com,
	tvboxspy@...il.com, crope@....fi, ruchandani.tina@...il.com,
	corbet@....net, chehabrafael@...il.com, k.kozlowski@...sung.com,
	stefanr@...6.in-berlin.de, inki.dae@...sung.com,
	jh1009.sung@...sung.com, elfring@...rs.sourceforge.net,
	prabhakar.csengg@...il.com, sw0312.kim@...sung.com,
	p.zabel@...gutronix.de, ricardo.ribalda@...il.com,
	labbott@...oraproject.org, pierre-louis.bossart@...ux.intel.com,
	ricard.wanderlof@...s.com, julian@...st.de, takamichiho@...il.com,
	dominic.sacre@....de, misterpib@...il.com, daniel@...que.org,
	gtmkramer@...all.nl, normalperson@...t.net, joe@...po.co.uk,
	linuxbugs@...tgam.net, johan@...ud.se,
	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	linux-api@...r.kernel.org, alsa-devel@...a-project.org
Subject: [PATCH 29/31] media: track media device unregister in progress

Add support to track media device unregister in progress
state to prevent more than one driver entering unregister.
This enables fixing the general protection faults while
snd-usb-audio was cleaning up media resources for pcm
streams and mixers. In this patch a new interface is added
to return the unregister in progress state. Subsequent
patches to snd-usb-audio and au0828-core use this interface
to avoid entering unregister and attempting to unregister
entities and remove devnodes while unregister is in progress.
Media device unregister removes entities and interface nodes.

Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
---
 drivers/media/media-device.c |  5 ++++-
 include/media/media-device.h | 17 +++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index 20c85a9..1bb9a5f 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -749,10 +749,13 @@ void media_device_unregister(struct media_device *mdev)
 	spin_lock(&mdev->lock);
 
 	/* Check if mdev was ever registered at all */
-	if (!media_devnode_is_registered(&mdev->devnode)) {
+	/* check if unregister is in progress */
+	if (!media_devnode_is_registered(&mdev->devnode) ||
+	    mdev->unregister_in_progress) {
 		spin_unlock(&mdev->lock);
 		return;
 	}
+	mdev->unregister_in_progress = true;
 
 	/* Remove all entities from the media device */
 	list_for_each_entry_safe(entity, next, &mdev->entities, graph_obj.list)
diff --git a/include/media/media-device.h b/include/media/media-device.h
index 04b6c2e..0807292 100644
--- a/include/media/media-device.h
+++ b/include/media/media-device.h
@@ -332,6 +332,10 @@ struct media_device {
 	spinlock_t lock;
 	/* Serializes graph operations. */
 	struct mutex graph_mutex;
+	/* Tracks unregister in progress state to prevent
+	 * more than one driver entering unregister
+	*/
+	bool unregister_in_progress;
 
 	/* Handlers to find source entity for the sink entity and
 	 * check if it is available, and activate the link using
@@ -365,6 +369,7 @@ struct media_device {
 /* media_devnode to media_device */
 #define to_media_device(node) container_of(node, struct media_device, devnode)
 
+
 /**
  * media_entity_enum_init - Initialise an entity enumeration
  *
@@ -553,6 +558,12 @@ struct media_device *media_device_get_devres(struct device *dev);
  * @dev: pointer to struct &device.
  */
 struct media_device *media_device_find_devres(struct device *dev);
+/* return unregister in progress state */
+static inline bool media_device_is_unregister_in_progress(
+					struct media_device *mdev)
+{
+	return mdev->unregister_in_progress;
+}
 
 /* Iterate over all entities. */
 #define media_device_for_each_entity(entity, mdev)			\
@@ -569,6 +580,7 @@ struct media_device *media_device_find_devres(struct device *dev);
 /* Iterate over all links. */
 #define media_device_for_each_link(link, mdev)			\
 	list_for_each_entry(link, &(mdev)->links, graph_obj.list)
+
 #else
 static inline int media_device_register(struct media_device *mdev)
 {
@@ -604,5 +616,10 @@ static inline struct media_device *media_device_find_devres(struct device *dev)
 {
 	return NULL;
 }
+static inline bool media_device_is_unregister_in_progress(
+					struct media_device *mdev)
+{
+	return false;
+}
 #endif /* CONFIG_MEDIA_CONTROLLER */
 #endif
-- 
2.5.0

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/