| Message ID | 1308126986-7679-1-git-send-email-laurent.pinchart@ideasonboard.com (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
Mauro, I forgot to mention in the subject line that this fix should go to 3.0. It fixes a kernel oops when a UVC webcam is disconnected during streaming. I'll send a pull request in the next few days after getting an ack on this patch. Hans, could you please test if it fixes your issue ?
Laurent Pinchart wrote: > Entities associated with video device nodes are unregistered in > video_unregister_device(). This destroys the entity even though it can > still be accessed through open video device nodes. > > Move the media_device_unregister_entity() call from > video_unregister_device() to v4l2_device_release() to ensure that the > entity isn't unregistered until the last reference to the video device > is released. > > Also remove the media_entity_get()/put() calls from v4l2-dev.c. Those > functions were designed for subdevs, to avoid a parent module from being > removed while still accessible through board code. They're not currently > needed for video device nodes, and will oops when a hotpluggable device > is disconnected during streaming, as media_entity_put() called in > v4l2_device_release() tries to access entity->parent->dev->driver which > is set to NULL when the device is disconnected. Thanks for the patch, Laurent! Acked-by: Sakari Ailus <sakari.ailus@iki.fi>
On Wednesday, June 15, 2011 10:36:26 Laurent Pinchart wrote: > Entities associated with video device nodes are unregistered in > video_unregister_device(). This destroys the entity even though it can > still be accessed through open video device nodes. > > Move the media_device_unregister_entity() call from > video_unregister_device() to v4l2_device_release() to ensure that the > entity isn't unregistered until the last reference to the video device > is released. > > Also remove the media_entity_get()/put() calls from v4l2-dev.c. Those > functions were designed for subdevs, to avoid a parent module from being > removed while still accessible through board code. They're not currently > needed for video device nodes, and will oops when a hotpluggable device > is disconnected during streaming, as media_entity_put() called in > v4l2_device_release() tries to access entity->parent->dev->driver which > is set to NULL when the device is disconnected. Looks good. Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Regards, Hans > > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > --- > drivers/media/video/v4l2-dev.c | 36 +++++++----------------------------- > 1 files changed, 7 insertions(+), 29 deletions(-) > > diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c > index 19d5ae2..5dc1fa1 100644 > --- a/drivers/media/video/v4l2-dev.c > +++ b/drivers/media/video/v4l2-dev.c > @@ -167,6 +167,12 @@ static void v4l2_device_release(struct device *cd) > > mutex_unlock(&videodev_lock); > > +#if defined(CONFIG_MEDIA_CONTROLLER) > + if (vdev->v4l2_dev && vdev->v4l2_dev->mdev && > + vdev->vfl_type != VFL_TYPE_SUBDEV) > + media_device_unregister_entity(&vdev->entity); > +#endif > + > /* Release video_device and perform other > cleanups as needed. */ > vdev->release(vdev); > @@ -405,17 +411,6 @@ static int v4l2_open(struct inode *inode, struct file *filp) > /* and increase the device refcount */ > video_get(vdev); > mutex_unlock(&videodev_lock); > -#if defined(CONFIG_MEDIA_CONTROLLER) > - if (vdev->v4l2_dev && vdev->v4l2_dev->mdev && > - vdev->vfl_type != VFL_TYPE_SUBDEV) { > - entity = media_entity_get(&vdev->entity); > - if (!entity) { > - ret = -EBUSY; > - video_put(vdev); > - return ret; > - } > - } > -#endif > if (vdev->fops->open) { > if (vdev->lock && mutex_lock_interruptible(vdev->lock)) { > ret = -ERESTARTSYS; > @@ -431,14 +426,8 @@ static int v4l2_open(struct inode *inode, struct file *filp) > > err: > /* decrease the refcount in case of an error */ > - if (ret) { > -#if defined(CONFIG_MEDIA_CONTROLLER) > - if (vdev->v4l2_dev && vdev->v4l2_dev->mdev && > - vdev->vfl_type != VFL_TYPE_SUBDEV) > - media_entity_put(entity); > -#endif > + if (ret) > video_put(vdev); > - } > return ret; > } > > @@ -455,11 +444,6 @@ static int v4l2_release(struct inode *inode, struct file *filp) > if (vdev->lock) > mutex_unlock(vdev->lock); > } > -#if defined(CONFIG_MEDIA_CONTROLLER) > - if (vdev->v4l2_dev && vdev->v4l2_dev->mdev && > - vdev->vfl_type != VFL_TYPE_SUBDEV) > - media_entity_put(&vdev->entity); > -#endif > /* decrease the refcount unconditionally since the release() > return value is ignored. */ > video_put(vdev); > @@ -754,12 +738,6 @@ void video_unregister_device(struct video_device *vdev) > if (!vdev || !video_is_registered(vdev)) > return; > > -#if defined(CONFIG_MEDIA_CONTROLLER) > - if (vdev->v4l2_dev && vdev->v4l2_dev->mdev && > - vdev->vfl_type != VFL_TYPE_SUBDEV) > - media_device_unregister_entity(&vdev->entity); > -#endif > - > mutex_lock(&videodev_lock); > /* This must be in a critical section to prevent a race with v4l2_open. > * Once this bit has been cleared video_get may never be called again. > -- > 1.7.3.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c index 19d5ae2..5dc1fa1 100644 --- a/drivers/media/video/v4l2-dev.c +++ b/drivers/media/video/v4l2-dev.c @@ -167,6 +167,12 @@ static void v4l2_device_release(struct device *cd) mutex_unlock(&videodev_lock); +#if defined(CONFIG_MEDIA_CONTROLLER) + if (vdev->v4l2_dev && vdev->v4l2_dev->mdev && + vdev->vfl_type != VFL_TYPE_SUBDEV) + media_device_unregister_entity(&vdev->entity); +#endif + /* Release video_device and perform other cleanups as needed. */ vdev->release(vdev); @@ -405,17 +411,6 @@ static int v4l2_open(struct inode *inode, struct file *filp) /* and increase the device refcount */ video_get(vdev); mutex_unlock(&videodev_lock); -#if defined(CONFIG_MEDIA_CONTROLLER) - if (vdev->v4l2_dev && vdev->v4l2_dev->mdev && - vdev->vfl_type != VFL_TYPE_SUBDEV) { - entity = media_entity_get(&vdev->entity); - if (!entity) { - ret = -EBUSY; - video_put(vdev); - return ret; - } - } -#endif if (vdev->fops->open) { if (vdev->lock && mutex_lock_interruptible(vdev->lock)) { ret = -ERESTARTSYS; @@ -431,14 +426,8 @@ static int v4l2_open(struct inode *inode, struct file *filp) err: /* decrease the refcount in case of an error */ - if (ret) { -#if defined(CONFIG_MEDIA_CONTROLLER) - if (vdev->v4l2_dev && vdev->v4l2_dev->mdev && - vdev->vfl_type != VFL_TYPE_SUBDEV) - media_entity_put(entity); -#endif + if (ret) video_put(vdev); - } return ret; } @@ -455,11 +444,6 @@ static int v4l2_release(struct inode *inode, struct file *filp) if (vdev->lock) mutex_unlock(vdev->lock); } -#if defined(CONFIG_MEDIA_CONTROLLER) - if (vdev->v4l2_dev && vdev->v4l2_dev->mdev && - vdev->vfl_type != VFL_TYPE_SUBDEV) - media_entity_put(&vdev->entity); -#endif /* decrease the refcount unconditionally since the release() return value is ignored. */ video_put(vdev); @@ -754,12 +738,6 @@ void video_unregister_device(struct video_device *vdev) if (!vdev || !video_is_registered(vdev)) return; -#if defined(CONFIG_MEDIA_CONTROLLER) - if (vdev->v4l2_dev && vdev->v4l2_dev->mdev && - vdev->vfl_type != VFL_TYPE_SUBDEV) - media_device_unregister_entity(&vdev->entity); -#endif - mutex_lock(&videodev_lock); /* This must be in a critical section to prevent a race with v4l2_open. * Once this bit has been cleared video_get may never be called again.
Entities associated with video device nodes are unregistered in video_unregister_device(). This destroys the entity even though it can still be accessed through open video device nodes. Move the media_device_unregister_entity() call from video_unregister_device() to v4l2_device_release() to ensure that the entity isn't unregistered until the last reference to the video device is released. Also remove the media_entity_get()/put() calls from v4l2-dev.c. Those functions were designed for subdevs, to avoid a parent module from being removed while still accessible through board code. They're not currently needed for video device nodes, and will oops when a hotpluggable device is disconnected during streaming, as media_entity_put() called in v4l2_device_release() tries to access entity->parent->dev->driver which is set to NULL when the device is disconnected. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> --- drivers/media/video/v4l2-dev.c | 36 +++++++----------------------------- 1 files changed, 7 insertions(+), 29 deletions(-)