| Message ID | 151cfbe0e59b3d5396951bdcc29666614575f5bc.1452105878.git.shuahkh@osg.samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Em Wed, 6 Jan 2016 13:27:18 -0700 Shuah Khan <shuahkh@osg.samsung.com> escreveu: > 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. Hmm... isn't the spinlock enough to serialize it? It seems weird the need of an extra bool here to warrant that this is really serialized. > > Signed-off-by: Shuah Khan <shuahkh@osg.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
On 01/28/2016 10:01 AM, Mauro Carvalho Chehab wrote: > Em Wed, 6 Jan 2016 13:27:18 -0700 > Shuah Khan <shuahkh@osg.samsung.com> escreveu: > >> 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. > > Hmm... isn't the spinlock enough to serialize it? It seems weird the > need of an extra bool here to warrant that this is really serialized. > The spinlock and check for media_devnode_is_registered(&mdev->devnode) aren't enough to ensure only one driver enters the unregister. Please note that the devnode isn't marked unregistered until the end in media_device_unregister(). >> >> Signed-off-by: Shuah Khan <shuahkh@osg.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
Em Thu, 28 Jan 2016 10:04:24 -0700 Shuah Khan <shuahkh@osg.samsung.com> escreveu: > On 01/28/2016 10:01 AM, Mauro Carvalho Chehab wrote: > > Em Wed, 6 Jan 2016 13:27:18 -0700 > > Shuah Khan <shuahkh@osg.samsung.com> escreveu: > > > >> 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. > > > > Hmm... isn't the spinlock enough to serialize it? It seems weird the > > need of an extra bool here to warrant that this is really serialized. > > > > The spinlock and check for media_devnode_is_registered(&mdev->devnode) > aren't enough to ensure only one driver enters the unregister. > > Please > note that the devnode isn't marked unregistered until the end in > media_device_unregister(). I guess the call to: device_remove_file(&mdev->devnode.dev, &dev_attr_model); IMO, This should be, instead, at media_devnode_unregister(). Then, we can change the logic at media_devnode_unregister() to: void media_devnode_unregister(struct media_devnode *mdev) { mutex_lock(&media_devnode_lock); /* Check if mdev was ever registered at all */ if (!media_devnode_is_registered(mdev)) { mutex_unlock(&media_devnode_lock); return; } clear_bit(MEDIA_FLAG_REGISTERED, &mdev->flags); mutex_unlock(&media_devnode_lock); device_remove_file(&mdev->devnode.dev, &dev_attr_model); device_unregister(&mdev->dev); } This sounds enough to avoid device_unregister() or device_remove_file() to be called twice. > > > >> > >> Signed-off-by: Shuah Khan <shuahkh@osg.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 > >
On 01/28/2016 10:28 AM, Mauro Carvalho Chehab wrote: > Em Thu, 28 Jan 2016 10:04:24 -0700 > Shuah Khan <shuahkh@osg.samsung.com> escreveu: > >> On 01/28/2016 10:01 AM, Mauro Carvalho Chehab wrote: >>> Em Wed, 6 Jan 2016 13:27:18 -0700 >>> Shuah Khan <shuahkh@osg.samsung.com> escreveu: >>> >>>> 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. >>> >>> Hmm... isn't the spinlock enough to serialize it? It seems weird the >>> need of an extra bool here to warrant that this is really serialized. >>> >> >> The spinlock and check for media_devnode_is_registered(&mdev->devnode) >> aren't enough to ensure only one driver enters the unregister. >> >> Please >> note that the devnode isn't marked unregistered until the end in >> media_device_unregister(). > > I guess the call to: > device_remove_file(&mdev->devnode.dev, &dev_attr_model); > > IMO, This should be, instead, at media_devnode_unregister(). > > Then, we can change the logic at media_devnode_unregister() to: > > void media_devnode_unregister(struct media_devnode *mdev) > { > mutex_lock(&media_devnode_lock); > > /* Check if mdev was ever registered at all */ > if (!media_devnode_is_registered(mdev)) { > mutex_unlock(&media_devnode_lock); > return; > } > > clear_bit(MEDIA_FLAG_REGISTERED, &mdev->flags); > mutex_unlock(&media_devnode_lock); > device_remove_file(&mdev->devnode.dev, &dev_attr_model); > device_unregister(&mdev->dev); > } > > This sounds enough to avoid device_unregister() or device_remove_file() > to be called twice. > I can give it a try. There might other problems that could result from media device being a devres in this case. The last put_device on the usbdev parent device (media device is created as devres for this), all device resources get released. That might have to be solved in a different way. For now I will see if your solution works. thanks, -- Shuah
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
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@osg.samsung.com> --- drivers/media/media-device.c | 5 ++++- include/media/media-device.h | 17 +++++++++++++++++ 2 files changed, 21 insertions(+), 1 deletion(-)