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Message-ID: <Z9Q5oTXEPPIoGWgE@kekkonen.localdomain>
Date: Fri, 14 Mar 2025 14:13:53 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Sebastian Fricke <sebastian.fricke@...labora.com>
Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Hans Verkuil <hverkuil@...all.nl>,
Tiffany Lin <tiffany.lin@...iatek.com>,
Andrew-CT Chen <andrew-ct.chen@...iatek.com>,
Yunfei Dong <yunfei.dong@...iatek.com>,
Matthias Brugger <matthias.bgg@...il.com>,
AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-mediatek@...ts.infradead.org, kernel@...labora.com
Subject: Re: [PATCH 3/5] media: mc: add debugfs node to keep track of requests
Hi Sebastian,
On Fri, Mar 14, 2025 at 02:26:28PM +0100, Sebastian Fricke wrote:
> From: Hans Verkuil <hverkuil@...all.nl>
>
> Keep track of the number of requests and request objects of a media
> device. Helps to verify that all request-related memory is freed.
>
> Signed-off-by: Hans Verkuil <hverkuil-cisco@...all.nl>
> ---
> drivers/media/mc/mc-device.c | 30 ++++++++++++++++++++++++++++++
> drivers/media/mc/mc-devnode.c | 5 +++++
> drivers/media/mc/mc-request.c | 6 ++++++
> include/media/media-device.h | 9 +++++++++
> include/media/media-devnode.h | 4 ++++
> include/media/media-request.h | 2 ++
> 6 files changed, 56 insertions(+)
>
> diff --git a/drivers/media/mc/mc-device.c b/drivers/media/mc/mc-device.c
> index c0dd4ae5722725f1744bc6fd6282d5c765438059..5a458160200afb540d8014fed42d8bf2dab9c8c3 100644
> --- a/drivers/media/mc/mc-device.c
> +++ b/drivers/media/mc/mc-device.c
> @@ -679,6 +679,23 @@ void media_device_unregister_entity(struct media_entity *entity)
> }
> EXPORT_SYMBOL_GPL(media_device_unregister_entity);
>
> +#ifdef CONFIG_DEBUG_FS
> +/*
> + * Log the state of media requests.
> + * Very useful for debugging.
> + */
> +static int media_device_requests(struct seq_file *file, void *priv)
> +{
> + struct media_device *dev = dev_get_drvdata(file->private);
Hmm. Can't you obtain struct media_device via struct device (dev field in
struct media_devnode is what I believe you have here)?
> +
> + seq_printf(file, "number of requests: %d\n",
> + atomic_read(&dev->num_requests));
> + seq_printf(file, "number of request objects: %d\n",
> + atomic_read(&dev->num_request_objects));
> + return 0;
> +}
> +#endif
> +
> void media_device_init(struct media_device *mdev)
> {
> INIT_LIST_HEAD(&mdev->entities);
> @@ -697,6 +714,9 @@ void media_device_init(struct media_device *mdev)
> media_set_bus_info(mdev->bus_info, sizeof(mdev->bus_info),
> mdev->dev);
>
> + atomic_set(&mdev->num_requests, 0);
> + atomic_set(&mdev->num_request_objects, 0);
> +
> dev_dbg(mdev->dev, "Media device initialized\n");
> }
> EXPORT_SYMBOL_GPL(media_device_init);
> @@ -748,6 +768,15 @@ int __must_check __media_device_register(struct media_device *mdev,
>
> dev_dbg(mdev->dev, "Media device registered\n");
>
> +#ifdef CONFIG_DEBUG_FS
> + if (!media_debugfs_root)
> + media_debugfs_root = debugfs_create_dir("media", NULL);
> + mdev->media_dir = debugfs_create_dir(dev_name(&devnode->dev),
> + media_debugfs_root);
> + debugfs_create_devm_seqfile(&devnode->dev, "requests",
> + mdev->media_dir, media_device_requests);
> +#endif
> +
> return 0;
> }
> EXPORT_SYMBOL_GPL(__media_device_register);
> @@ -824,6 +853,7 @@ void media_device_unregister(struct media_device *mdev)
>
> dev_dbg(mdev->dev, "Media device unregistered\n");
>
> + debugfs_remove_recursive(mdev->media_dir);
> device_remove_file(&mdev->devnode->dev, &dev_attr_model);
> media_devnode_unregister(mdev->devnode);
> /* devnode free is handled in media_devnode_*() */
> diff --git a/drivers/media/mc/mc-devnode.c b/drivers/media/mc/mc-devnode.c
> index 56444edaf13651874331e7c04e86b0a585067d38..d0a8bcc11dd6350fdbc04add70f62de2c5f01178 100644
> --- a/drivers/media/mc/mc-devnode.c
> +++ b/drivers/media/mc/mc-devnode.c
> @@ -45,6 +45,9 @@ static dev_t media_dev_t;
> static DEFINE_MUTEX(media_devnode_lock);
> static DECLARE_BITMAP(media_devnode_nums, MEDIA_NUM_DEVICES);
>
> +/* debugfs */
> +struct dentry *media_debugfs_root;
> +
> /* Called when the last user of the media device exits. */
> static void media_devnode_release(struct device *cd)
> {
> @@ -236,6 +239,7 @@ int __must_check media_devnode_register(struct media_device *mdev,
> if (devnode->parent)
> devnode->dev.parent = devnode->parent;
> dev_set_name(&devnode->dev, "media%d", devnode->minor);
> + dev_set_drvdata(&devnode->dev, mdev);
> device_initialize(&devnode->dev);
>
> /* Part 2: Initialize the character device */
> @@ -313,6 +317,7 @@ static int __init media_devnode_init(void)
>
> static void __exit media_devnode_exit(void)
> {
> + debugfs_remove_recursive(media_debugfs_root);
> bus_unregister(&media_bus_type);
> unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES);
> }
> diff --git a/drivers/media/mc/mc-request.c b/drivers/media/mc/mc-request.c
> index 398d0806d1d274eb8c454fc5c37b77476abe1e74..829e35a5d56d41c52cc583cdea1c959bcb4fce60 100644
> --- a/drivers/media/mc/mc-request.c
> +++ b/drivers/media/mc/mc-request.c
> @@ -75,6 +75,7 @@ static void media_request_release(struct kref *kref)
> mdev->ops->req_free(req);
> else
> kfree(req);
> + atomic_dec(&mdev->num_requests);
> }
>
> void media_request_put(struct media_request *req)
> @@ -326,6 +327,7 @@ int media_request_alloc(struct media_device *mdev, int *alloc_fd)
>
> snprintf(req->debug_str, sizeof(req->debug_str), "%u:%d",
> atomic_inc_return(&mdev->request_id), fd);
> + atomic_inc(&mdev->num_requests);
> dev_dbg(mdev->dev, "request: allocated %s\n", req->debug_str);
>
> fd_install(fd, filp);
> @@ -349,10 +351,12 @@ static void media_request_object_release(struct kref *kref)
> struct media_request_object *obj =
> container_of(kref, struct media_request_object, kref);
> struct media_request *req = obj->req;
> + struct media_device *mdev = obj->mdev;
>
> if (WARN_ON(req))
> media_request_object_unbind(obj);
> obj->ops->release(obj);
> + atomic_dec(&mdev->num_request_objects);
> }
>
> struct media_request_object *
> @@ -417,6 +421,7 @@ int media_request_object_bind(struct media_request *req,
> obj->req = req;
> obj->ops = ops;
> obj->priv = priv;
> + obj->mdev = req->mdev;
>
> if (is_buffer)
> list_add_tail(&obj->list, &req->objects);
> @@ -424,6 +429,7 @@ int media_request_object_bind(struct media_request *req,
> list_add(&obj->list, &req->objects);
> req->num_incomplete_objects++;
> ret = 0;
> + atomic_inc(&obj->mdev->num_request_objects);
>
> unlock:
> spin_unlock_irqrestore(&req->lock, flags);
> diff --git a/include/media/media-device.h b/include/media/media-device.h
> index 53d2a16a70b0d9d6e5cc28fe1fc5d5ef384410d5..749c327e3c582c3c583e0394468321ccd6160da5 100644
> --- a/include/media/media-device.h
> +++ b/include/media/media-device.h
> @@ -11,6 +11,7 @@
> #ifndef _MEDIA_DEVICE_H
> #define _MEDIA_DEVICE_H
>
> +#include <linux/atomic.h>
> #include <linux/list.h>
> #include <linux/mutex.h>
> #include <linux/pci.h>
> @@ -106,6 +107,9 @@ struct media_device_ops {
> * @ops: Operation handler callbacks
> * @req_queue_mutex: Serialise the MEDIA_REQUEST_IOC_QUEUE ioctl w.r.t.
> * other operations that stop or start streaming.
> + * @num_requests: number of associated requests
> + * @num_request_objects: number of associated request objects
> + * @media_dir: DebugFS media directory
> * @request_id: Used to generate unique request IDs
> *
> * This structure represents an abstract high-level media device. It allows easy
> @@ -179,6 +183,11 @@ struct media_device {
> const struct media_device_ops *ops;
>
> struct mutex req_queue_mutex;
> + atomic_t num_requests;
> + atomic_t num_request_objects;
> +
> + /* debugfs */
> + struct dentry *media_dir;
> atomic_t request_id;
> };
>
> diff --git a/include/media/media-devnode.h b/include/media/media-devnode.h
> index d27c1c646c2805171be3997d72210dd4d1a38e32..dbcabeffcb572ae707f5fe1f51ff719d451c6784 100644
> --- a/include/media/media-devnode.h
> +++ b/include/media/media-devnode.h
> @@ -20,9 +20,13 @@
> #include <linux/fs.h>
> #include <linux/device.h>
> #include <linux/cdev.h>
> +#include <linux/debugfs.h>
>
> struct media_device;
>
> +/* debugfs top-level media directory */
> +extern struct dentry *media_debugfs_root;
> +
> /*
> * Flag to mark the media_devnode struct as registered. Drivers must not touch
> * this flag directly, it will be set and cleared by media_devnode_register and
> diff --git a/include/media/media-request.h b/include/media/media-request.h
> index 645d18907be7148ca50dcc9248ff06bd8ccdf953..c8dad380c40767f192f30dcf1c69b9ad1310f449 100644
> --- a/include/media/media-request.h
> +++ b/include/media/media-request.h
> @@ -290,6 +290,7 @@ struct media_request_object_ops {
> * struct media_request_object - An opaque object that belongs to a media
> * request
> *
> + * @mdev: Media device this object belongs to
> * @ops: object's operations
> * @priv: object's priv pointer
> * @req: the request this object belongs to (can be NULL)
> @@ -301,6 +302,7 @@ struct media_request_object_ops {
> * another struct that contains the actual data for this request object.
> */
> struct media_request_object {
> + struct media_device *mdev;
> const struct media_request_object_ops *ops;
> void *priv;
> struct media_request *req;
>
--
Regards,
Sakari Ailus
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