diff options
| -rw-r--r-- | drivers/media/video/pvrusb2/pvrusb2-v4l2.c | 111 |
1 files changed, 36 insertions, 75 deletions
diff --git a/drivers/media/video/pvrusb2/pvrusb2-v4l2.c b/drivers/media/video/pvrusb2/pvrusb2-v4l2.c index 156e375..f4c54ef 100644 --- a/drivers/media/video/pvrusb2/pvrusb2-v4l2.c +++ b/drivers/media/video/pvrusb2/pvrusb2-v4l2.c @@ -28,6 +28,7 @@ #include "pvrusb2-debug.h" #include "pvrusb2-v4l2.h" #include "pvrusb2-ioread.h" +#include <linux/videodev.h> #include <linux/videodev2.h> #include <media/v4l2-common.h> @@ -35,21 +36,10 @@ struct pvr2_v4l2_dev; struct pvr2_v4l2_fh; struct pvr2_v4l2; -/* V4L no longer provide the ability to set / get a private context pointer - (i.e. video_get_drvdata / video_set_drvdata), which means we have to - concoct our own context locating mechanism. Supposedly this is intended - to simplify driver implementation. It's not clear to me how that can - possibly be true. Our solution here is to maintain a lookup table of - our context instances, indexed by the minor device number of the V4L - device. See pvr2_v4l2_open() for some implications of this approach. */ -static struct pvr2_v4l2_dev *devices[256]; -static DEFINE_MUTEX(device_lock); - struct pvr2_v4l2_dev { + struct video_device devbase; /* MUST be first! */ struct pvr2_v4l2 *v4lp; - struct video_device *vdev; struct pvr2_context_stream *stream; - int ctxt_idx; enum pvr2_config config; }; @@ -74,7 +64,7 @@ struct pvr2_v4l2 { struct v4l2_prio_state prio; /* streams */ - struct pvr2_v4l2_dev video_dev; + struct pvr2_v4l2_dev *vdev; }; static int video_nr[PVR_NUM] = {[0 ... PVR_NUM-1] = -1}; @@ -718,21 +708,22 @@ static int pvr2_v4l2_do_ioctl(struct inode *inode, struct file *file, static void pvr2_v4l2_dev_destroy(struct pvr2_v4l2_dev *dip) { printk(KERN_INFO "pvrusb2: unregistering device video%d [%s]\n", - dip->vdev->minor,pvr2_config_get_name(dip->config)); - if (dip->ctxt_idx >= 0) { - mutex_lock(&device_lock); - devices[dip->ctxt_idx] = NULL; - dip->ctxt_idx = -1; - mutex_unlock(&device_lock); - } - video_unregister_device(dip->vdev); + dip->devbase.minor,pvr2_config_get_name(dip->config)); + + /* Paranoia */ + dip->v4lp = 0; + dip->stream = 0; + + /* Actual deallocation happens later when all internal references + are gone. */ + video_unregister_device(&dip->devbase); } static void pvr2_v4l2_destroy_no_lock(struct pvr2_v4l2 *vp) { pvr2_hdw_v4l_store_minor_number(vp->channel.mc_head->hdw,-1); - pvr2_v4l2_dev_destroy(&vp->video_dev); + pvr2_v4l2_dev_destroy(vp->vdev); pvr2_trace(PVR2_TRACE_STRUCT,"Destroying pvr2_v4l2 id=%p",vp); pvr2_channel_done(&vp->channel); @@ -740,6 +731,14 @@ static void pvr2_v4l2_destroy_no_lock(struct pvr2_v4l2 *vp) } +static void pvr2_video_device_release(struct video_device *vdev) +{ + struct pvr2_v4l2_dev *dev; + dev = container_of(vdev,struct pvr2_v4l2_dev,devbase); + kfree(dev); +} + + static void pvr2_v4l2_internal_check(struct pvr2_channel *chp) { struct pvr2_v4l2 *vp; @@ -811,40 +810,12 @@ static int pvr2_v4l2_release(struct inode *inode, struct file *file) static int pvr2_v4l2_open(struct inode *inode, struct file *file) { - struct pvr2_v4l2_dev *dip = NULL; /* Our own context pointer */ + struct pvr2_v4l2_dev *dip; /* Our own context pointer */ struct pvr2_v4l2_fh *fhp; struct pvr2_v4l2 *vp; struct pvr2_hdw *hdw; - mutex_lock(&device_lock); - /* MCI 7-Jun-2006 Even though we're just doing what amounts to an - atomic read of the device mapping array here, we still need the - mutex. The problem is that there is a tiny race possible when - we register the device. We can't update the device mapping - array until after the device has been registered, owing to the - fact that we can't know the minor device number until after the - registration succeeds. And if another thread tries to open the - device in the window of time after registration but before the - map is updated, then it will get back an erroneous null pointer - and the open will result in a spurious failure. The only way to - prevent that is to (a) be inside the mutex here before we access - the array, and (b) cover the entire registration process later - on with this same mutex. Thus if we get inside the mutex here, - then we can be assured that the registration process actually - completed correctly. This is an unhappy complication from the - use of global data in a driver that lives in a preemptible - environment. It sure would be nice if the video device itself - had a means for storing and retrieving a local context pointer. - Oh wait. It did. But now it's gone. Silly me. */ - { - unsigned int midx = iminor(file->f_dentry->d_inode); - if (midx < sizeof(devices)/sizeof(devices[0])) { - dip = devices[midx]; - } - } - mutex_unlock(&device_lock); - - if (!dip) return -ENODEV; /* Should be impossible but I'm paranoid */ + dip = container_of(video_devdata(file),struct pvr2_v4l2_dev,devbase); vp = dip->v4lp; hdw = vp->channel.hdw; @@ -1074,38 +1045,24 @@ static void pvr2_v4l2_dev_init(struct pvr2_v4l2_dev *dip, return; } - dip->vdev = video_device_alloc(); - if (!dip->vdev) { - err("Alloc of pvrusb2 v4l video device failed"); - return; - } - - memcpy(dip->vdev,&vdev_template,sizeof(vdev_template)); - dip->vdev->release = video_device_release; - mutex_lock(&device_lock); + memcpy(&dip->devbase,&vdev_template,sizeof(vdev_template)); + dip->devbase.release = pvr2_video_device_release; mindevnum = -1; unit_number = pvr2_hdw_get_unit_number(vp->channel.mc_head->hdw); if ((unit_number >= 0) && (unit_number < PVR_NUM)) { mindevnum = video_nr[unit_number]; } - if ((video_register_device(dip->vdev, v4l_type, mindevnum) < 0) && - (video_register_device(dip->vdev, v4l_type, -1) < 0)) { + if ((video_register_device(&dip->devbase, v4l_type, mindevnum) < 0) && + (video_register_device(&dip->devbase, v4l_type, -1) < 0)) { err("Failed to register pvrusb2 v4l video device"); } else { printk(KERN_INFO "pvrusb2: registered device video%d [%s]\n", - dip->vdev->minor,pvr2_config_get_name(dip->config)); + dip->devbase.minor,pvr2_config_get_name(dip->config)); } - if ((dip->vdev->minor < sizeof(devices)/sizeof(devices[0])) && - (devices[dip->vdev->minor] == NULL)) { - dip->ctxt_idx = dip->vdev->minor; - devices[dip->ctxt_idx] = dip; - } - mutex_unlock(&device_lock); - pvr2_hdw_v4l_store_minor_number(vp->channel.mc_head->hdw, - dip->vdev->minor); + dip->devbase.minor); } @@ -1116,15 +1073,19 @@ struct pvr2_v4l2 *pvr2_v4l2_create(struct pvr2_context *mnp) vp = kmalloc(sizeof(*vp),GFP_KERNEL); if (!vp) return vp; memset(vp,0,sizeof(*vp)); - vp->video_dev.ctxt_idx = -1; + vp->vdev = kmalloc(sizeof(*vp->vdev),GFP_KERNEL); + if (!vp->vdev) { + kfree(vp); + return 0; + } + memset(vp->vdev,0,sizeof(*vp->vdev)); pvr2_channel_init(&vp->channel,mnp); pvr2_trace(PVR2_TRACE_STRUCT,"Creating pvr2_v4l2 id=%p",vp); vp->channel.check_func = pvr2_v4l2_internal_check; /* register streams */ - pvr2_v4l2_dev_init(&vp->video_dev,vp,pvr2_config_mpeg); - + pvr2_v4l2_dev_init(vp->vdev,vp,pvr2_config_mpeg); return vp; } |
