Commit 73a11062 authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
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media: v4l2-core: push taking ioctl mutex down to ioctl handler 



The ioctl serialization mutex (vdev->lock or q->lock for vb2 queues)
was taken at the highest level in v4l2-dev.c. This prevents more
fine-grained locking since at that level we cannot examine the ioctl
arguments, we can only do that after video_usercopy is called.

So push the locking down to __video_do_ioctl() and subdev_do_ioctl_lock().

This also allows us to make a few functions in v4l2-ioctl.c static and
video_usercopy() is no longer exported.

The locking scheme is not changed by this patch, just pushed down.

Signed-off-by: default avatarHans Verkuil <hansverk@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
parent eba09b5b

drivers/media/v4l2-core/v4l2-dev.c

+0 −6
Original line number Diff line number Diff line
@@ -360,14 +360,8 @@ static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 
	int ret = -ENODEV;



	if (vdev->fops->unlocked_ioctl) {

		struct mutex *lock = v4l2_ioctl_get_lock(vdev, cmd);



		if (lock && mutex_lock_interruptible(lock))

			return -ERESTARTSYS;

		if (video_is_registered(vdev))

			ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);

		if (lock)

			mutex_unlock(lock);

	} else

		ret = -ENOTTY;

drivers/media/v4l2-core/v4l2-ioctl.c

+17 −3
Original line number Diff line number Diff line
@@ -2655,14 +2655,15 @@ static struct v4l2_ioctl_info v4l2_ioctls[] = { 
};

#define V4L2_IOCTLS ARRAY_SIZE(v4l2_ioctls)



bool v4l2_is_known_ioctl(unsigned int cmd)

static bool v4l2_is_known_ioctl(unsigned int cmd)

{

	if (_IOC_NR(cmd) >= V4L2_IOCTLS)

		return false;

	return v4l2_ioctls[_IOC_NR(cmd)].ioctl == cmd;

}



struct mutex *v4l2_ioctl_get_lock(struct video_device *vdev, unsigned cmd)

static struct mutex *v4l2_ioctl_get_lock(struct video_device *vdev,

					 unsigned int cmd)

{

	if (_IOC_NR(cmd) >= V4L2_IOCTLS)

		return vdev->lock;
@@ -2713,6 +2714,7 @@ static long __video_do_ioctl(struct file *file, 
		unsigned int cmd, void *arg)

{

	struct video_device *vfd = video_devdata(file);

	struct mutex *lock; /* ioctl serialization mutex */

	const struct v4l2_ioctl_ops *ops = vfd->ioctl_ops;

	bool write_only = false;

	struct v4l2_ioctl_info default_info;
@@ -2731,6 +2733,16 @@ static long __video_do_ioctl(struct file *file, 
	if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags))

		vfh = file->private_data;



	lock = v4l2_ioctl_get_lock(vfd, cmd);



	if (lock && mutex_lock_interruptible(lock))

		return -ERESTARTSYS;



	if (!video_is_registered(vfd)) {

		ret = -ENODEV;

		goto unlock;

	}



	if (v4l2_is_known_ioctl(cmd)) {

		info = &v4l2_ioctls[_IOC_NR(cmd)];
@@ -2780,6 +2792,9 @@ done: 
		}

	}



unlock:

	if (lock)

		mutex_unlock(lock);

	return ret;

}
@@ -2969,7 +2984,6 @@ out: 
	kvfree(mbuf);

	return err;

}

EXPORT_SYMBOL(video_usercopy);



long video_ioctl2(struct file *file,

	       unsigned int cmd, unsigned long arg)

drivers/media/v4l2-core/v4l2-subdev.c

+16 −1
Original line number Diff line number Diff line
@@ -502,10 +502,25 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg) 
	return 0;

}



static long subdev_do_ioctl_lock(struct file *file, unsigned int cmd, void *arg)

{

	struct video_device *vdev = video_devdata(file);

	struct mutex *lock = vdev->lock;

	long ret = -ENODEV;



	if (lock && mutex_lock_interruptible(lock))

		return -ERESTARTSYS;

	if (video_is_registered(vdev))

		ret = subdev_do_ioctl(file, cmd, arg);

	if (lock)

		mutex_unlock(lock);

	return ret;

}



static long subdev_ioctl(struct file *file, unsigned int cmd,

	unsigned long arg)

{

	return video_usercopy(file, cmd, arg, subdev_do_ioctl);

	return video_usercopy(file, cmd, arg, subdev_do_ioctl_lock);

}



#ifdef CONFIG_COMPAT

include/media/v4l2-dev.h

+0 −9
Original line number Diff line number Diff line
@@ -435,15 +435,6 @@ void video_device_release(struct video_device *vdev); 
 */

void video_device_release_empty(struct video_device *vdev);



/**

 * v4l2_is_known_ioctl - Checks if a given cmd is a known V4L ioctl

 *

 * @cmd: ioctl command

 *

 * returns true if cmd is a known V4L2 ioctl

 */

bool v4l2_is_known_ioctl(unsigned int cmd);



/**

 * v4l2_disable_ioctl- mark that a given command isn't implemented.

 *	shouldn't use core locking

include/media/v4l2-ioctl.h

+0 −12
Original line number Diff line number Diff line
@@ -658,18 +658,6 @@ void v4l_printk_ioctl(const char *prefix, unsigned int cmd); 


struct video_device;





/**

 * v4l2_ioctl_get_lock - get the mutex (if any) that it is need to lock for

 *	a given command.

 *

 * @vdev: Pointer to struct &video_device.

 * @cmd: Ioctl name.

 *

 * .. note:: Internal use only. Should not be used outside V4L2 core.

 */

struct mutex *v4l2_ioctl_get_lock(struct video_device *vdev, unsigned int cmd);



/* names for fancy debug output */

extern const char *v4l2_field_names[];

extern const char *v4l2_type_names[];

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