mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-08-30 12:13:51 -04:00
Code Issues Packages Projects Releases Wiki Activity

media: em28xx: use v4l2_device release callback

Browse Source 
The em28xx driver creates a lot of video devices, but life-time management
is really bad. Instead use the struct v4l2_device release() callback to
have a single place where memory can be freed once the last user has gone.

Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Tested-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
This commit is contained in:
Hans Verkuil
2026-05-19 12:07:59 +02:00
committed by Mauro Carvalho Chehab
parent 4e72f13d58
commit 2882543836
2 changed files with 41 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

66
drivers/media/usb/em28xx/em28xx-video.c
View File

@@ -2275,18 +2275,27 @@ static int radio_s_tuner(struct file *file, void *priv,
}
/*
* em28xx_free_v4l2() - Free struct em28xx_v4l2
* em28xx_free_v4l2() - v4l2_device release callback
*
* @ref: struct kref for struct em28xx_v4l2
* @v4l2_dev: pointer to struct v4l2_device embedded in struct em28xx_v4l2
*
* Called when all users of struct em28xx_v4l2 are gone
* Called by the v4l2 core when the last reference to the v4l2_device is
* released. At this point no userspace file handle nor video_device node
* keeps the v4l2 instance alive anymore, so it is safe to release all
* v4l2-related resources and drop the em28xx device reference taken when
* the v4l2 extension was initialized.
*/
static void em28xx_free_v4l2(struct kref *ref)
static void em28xx_free_v4l2(struct v4l2_device *v4l2_dev)
{
struct em28xx_v4l2 *v4l2 = container_of(ref, struct em28xx_v4l2, ref);
struct em28xx_v4l2 *v4l2 =
container_of(v4l2_dev, struct em28xx_v4l2, v4l2_dev);
struct em28xx *dev = v4l2->dev;
v4l2->dev->v4l2 = NULL;
v4l2_ctrl_handler_free(&v4l2->ctrl_handler);
v4l2_device_unregister(v4l2_dev);
dev->v4l2 = NULL;
kfree(v4l2);
kref_put(&dev->ref, em28xx_free_device);
}
/*
@@ -2354,8 +2363,6 @@ static int em28xx_v4l2_open(struct file *filp)
v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, s_radio);
}
kref_get(&dev->ref);
kref_get(&v4l2->ref);
v4l2->users++;
mutex_unlock(&dev->lock);
@@ -2411,14 +2418,14 @@ static int em28xx_v4l2_fini(struct em28xx *dev)
video_unregister_device(&v4l2->vdev);
}
v4l2_ctrl_handler_free(&v4l2->ctrl_handler);
v4l2_device_unregister(&v4l2->v4l2_dev);
kref_put(&v4l2->ref, em28xx_free_v4l2);
mutex_unlock(&dev->lock);
kref_put(&dev->ref, em28xx_free_device);
/*
* Drop the initial reference taken at v4l2_device_register() time.
* The em28xx_free_v4l2() release callback will be invoked once all
* userspace file handles to the video device nodes are closed.
*/
v4l2_device_put(&v4l2->v4l2_dev);
return 0;
}
@@ -2490,9 +2497,7 @@ static int em28xx_v4l2_close(struct file *filp)
exit:
v4l2->users--;
kref_put(&v4l2->ref, em28xx_free_v4l2);
mutex_unlock(&dev->lock);
kref_put(&dev->ref, em28xx_free_device);
return 0;
}
@@ -2711,7 +2716,6 @@ static int em28xx_v4l2_init(struct em28xx *dev)
mutex_unlock(&dev->lock);
return -ENOMEM;
}
kref_init(&v4l2->ref);
v4l2->dev = dev;
dev->v4l2 = v4l2;
@@ -2722,9 +2726,21 @@ static int em28xx_v4l2_init(struct em28xx *dev)
if (ret < 0) {
dev_err(&dev->intf->dev,
"Call to v4l2_device_register() failed!\n");
goto err;
dev->v4l2 = NULL;
kfree(v4l2);
mutex_unlock(&dev->lock);
return ret;
}
/*
* From this point on, em28xx_free_v4l2() will be used to release
* v4l2-related resources when the v4l2_device refcount reaches
* zero. Take a reference to the em28xx device so that it cannot
* be freed before the v4l2 instance is released.
*/
v4l2->v4l2_dev.release = em28xx_free_v4l2;
kref_get(&dev->ref);
hdl = &v4l2->ctrl_handler;
v4l2_ctrl_handler_init(hdl, 9);
v4l2->v4l2_dev.ctrl_handler = hdl;
@@ -3048,8 +3064,6 @@ static int em28xx_v4l2_init(struct em28xx *dev)
dev_info(&dev->intf->dev,
"V4L2 extension successfully initialized\n");
kref_get(&dev->ref);
mutex_unlock(&dev->lock);
return 0;
@@ -3073,12 +3087,14 @@ static int em28xx_v4l2_init(struct em28xx *dev)
video_unregister_device(&v4l2->vdev);
}
v4l2_ctrl_handler_free(&v4l2->ctrl_handler);
v4l2_device_unregister(&v4l2->v4l2_dev);
err:
dev->v4l2 = NULL;
kref_put(&v4l2->ref, em28xx_free_v4l2);
mutex_unlock(&dev->lock);
/*
* Drop the initial reference. em28xx_free_v4l2() will be called
* once the last video_device node release has decremented the
* v4l2_device refcount to zero.
*/
v4l2_device_put(&v4l2->v4l2_dev);
return ret;
}

1
drivers/media/usb/em28xx/em28xx.h
View File

@@ -558,7 +558,6 @@ struct em28xx_eeprom {
#define EM28XX_RESOURCE_VBI 0x02
struct em28xx_v4l2 {
struct kref ref;
struct em28xx *dev;
struct v4l2_device v4l2_dev;