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-rw-r--r--Documentation/video4linux/v4l2-framework.txt20
-rw-r--r--drivers/media/video/v4l2-dev.c76
-rw-r--r--drivers/media/video/v4l2-event.c9
-rw-r--r--include/media/v4l2-dev.h3
4 files changed, 89 insertions, 19 deletions
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index 9b1d81c26b7d..a128e012a45c 100644
--- a/Documentation/video4linux/v4l2-framework.txt
+++ b/Documentation/video4linux/v4l2-framework.txt
@@ -453,6 +453,10 @@ You should also set these fields:
- ioctl_ops: if you use the v4l2_ioctl_ops to simplify ioctl maintenance
(highly recommended to use this and it might become compulsory in the
future!), then set this to your v4l2_ioctl_ops struct.
+- lock: leave to NULL if you want to do all the locking in the driver.
+ Otherwise you give it a pointer to a struct mutex_lock and before any
+ of the v4l2_file_operations is called this lock will be taken by the
+ core and released afterwards.
- parent: you only set this if v4l2_device was registered with NULL as
the parent device struct. This only happens in cases where one hardware
device has multiple PCI devices that all share the same v4l2_device core.
@@ -469,6 +473,22 @@ If you use v4l2_ioctl_ops, then you should set either .unlocked_ioctl or
The v4l2_file_operations struct is a subset of file_operations. The main
difference is that the inode argument is omitted since it is never used.
+v4l2_file_operations and locking
+--------------------------------
+
+You can set a pointer to a mutex_lock in struct video_device. Usually this
+will be either a top-level mutex or a mutex per device node. If you want
+finer-grained locking then you have to set it to NULL and do you own locking.
+
+If a lock is specified then all file operations will be serialized on that
+lock. If you use videobuf then you must pass the same lock to the videobuf
+queue initialize function: if videobuf has to wait for a frame to arrive, then
+it will temporarily unlock the lock and relock it afterwards. If your driver
+also waits in the code, then you should do the same to allow other processes
+to access the device node while the first process is waiting for something.
+
+The implementation of a hotplug disconnect should also take the lock before
+calling v4l2_device_disconnect and video_unregister_device.
video_device registration
-------------------------
diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index 5a54eabd4c42..a7702e3d149c 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -187,33 +187,50 @@ static ssize_t v4l2_read(struct file *filp, char __user *buf,
size_t sz, loff_t *off)
{
struct video_device *vdev = video_devdata(filp);
+ int ret = -EIO;
if (!vdev->fops->read)
return -EINVAL;
- if (!video_is_registered(vdev))
- return -EIO;
- return vdev->fops->read(filp, buf, sz, off);
+ if (vdev->lock)
+ mutex_lock(vdev->lock);
+ if (video_is_registered(vdev))
+ ret = vdev->fops->read(filp, buf, sz, off);
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
+ return ret;
}
static ssize_t v4l2_write(struct file *filp, const char __user *buf,
size_t sz, loff_t *off)
{
struct video_device *vdev = video_devdata(filp);
+ int ret = -EIO;
if (!vdev->fops->write)
return -EINVAL;
- if (!video_is_registered(vdev))
- return -EIO;
- return vdev->fops->write(filp, buf, sz, off);
+ if (vdev->lock)
+ mutex_lock(vdev->lock);
+ if (video_is_registered(vdev))
+ ret = vdev->fops->write(filp, buf, sz, off);
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
+ return ret;
}
static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
{
struct video_device *vdev = video_devdata(filp);
+ int ret = DEFAULT_POLLMASK;
- if (!vdev->fops->poll || !video_is_registered(vdev))
- return DEFAULT_POLLMASK;
- return vdev->fops->poll(filp, poll);
+ if (!vdev->fops->poll)
+ return ret;
+ if (vdev->lock)
+ mutex_lock(vdev->lock);
+ if (video_is_registered(vdev))
+ ret = vdev->fops->poll(filp, poll);
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
+ return ret;
}
static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
@@ -224,7 +241,11 @@ static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
if (!vdev->fops->ioctl)
return -ENOTTY;
if (vdev->fops->unlocked_ioctl) {
+ if (vdev->lock)
+ mutex_lock(vdev->lock);
ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
} else if (vdev->fops->ioctl) {
/* TODO: convert all drivers to unlocked_ioctl */
lock_kernel();
@@ -239,10 +260,17 @@ static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
{
struct video_device *vdev = video_devdata(filp);
+ int ret = -ENODEV;
- if (!vdev->fops->mmap || !video_is_registered(vdev))
- return -ENODEV;
- return vdev->fops->mmap(filp, vm);
+ if (!vdev->fops->mmap)
+ return ret;
+ if (vdev->lock)
+ mutex_lock(vdev->lock);
+ if (video_is_registered(vdev))
+ ret = vdev->fops->mmap(filp, vm);
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
+ return ret;
}
/* Override for the open function */
@@ -254,17 +282,24 @@ static int v4l2_open(struct inode *inode, struct file *filp)
/* Check if the video device is available */
mutex_lock(&videodev_lock);
vdev = video_devdata(filp);
- /* return ENODEV if the video device has been removed
- already or if it is not registered anymore. */
- if (vdev == NULL || !video_is_registered(vdev)) {
+ /* return ENODEV if the video device has already been removed. */
+ if (vdev == NULL) {
mutex_unlock(&videodev_lock);
return -ENODEV;
}
/* and increase the device refcount */
video_get(vdev);
mutex_unlock(&videodev_lock);
- if (vdev->fops->open)
- ret = vdev->fops->open(filp);
+ if (vdev->fops->open) {
+ if (vdev->lock)
+ mutex_lock(vdev->lock);
+ if (video_is_registered(vdev))
+ ret = vdev->fops->open(filp);
+ else
+ ret = -ENODEV;
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
+ }
/* decrease the refcount in case of an error */
if (ret)
@@ -278,8 +313,13 @@ static int v4l2_release(struct inode *inode, struct file *filp)
struct video_device *vdev = video_devdata(filp);
int ret = 0;
- if (vdev->fops->release)
+ if (vdev->fops->release) {
+ if (vdev->lock)
+ mutex_lock(vdev->lock);
vdev->fops->release(filp);
+ if (vdev->lock)
+ mutex_unlock(vdev->lock);
+ }
/* decrease the refcount unconditionally since the release()
return value is ignored. */
diff --git a/drivers/media/video/v4l2-event.c b/drivers/media/video/v4l2-event.c
index de74ce07b5e2..69fd343d4774 100644
--- a/drivers/media/video/v4l2-event.c
+++ b/drivers/media/video/v4l2-event.c
@@ -134,15 +134,22 @@ int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
if (nonblocking)
return __v4l2_event_dequeue(fh, event);
+ /* Release the vdev lock while waiting */
+ if (fh->vdev->lock)
+ mutex_unlock(fh->vdev->lock);
+
do {
ret = wait_event_interruptible(events->wait,
events->navailable != 0);
if (ret < 0)
- return ret;
+ break;
ret = __v4l2_event_dequeue(fh, event);
} while (ret == -ENOENT);
+ if (fh->vdev->lock)
+ mutex_lock(fh->vdev->lock);
+
return ret;
}
EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
index ba236ff35c8a..15802a067a12 100644
--- a/include/media/v4l2-dev.h
+++ b/include/media/v4l2-dev.h
@@ -94,6 +94,9 @@ struct video_device
/* ioctl callbacks */
const struct v4l2_ioctl_ops *ioctl_ops;
+
+ /* serialization lock */
+ struct mutex *lock;
};
/* dev to video-device */

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