[PATCH v6 3/5] drm: add debugfs support on per client-id basis

[Christian König]

On 27.06.25 11:49, Sunil Khatri wrote:
> add support to add a directory for each client-id
> with root at the dri level. Since the clients are
> unique and not just related to one single drm device,
> so it makes more sense to add all the client based
> nodes with root as dri.
> 
> Also create a debugfs file which show the process
> information for the client and create a symlink back
> to the parent drm device from each client.
> 
> Signed-off-by: Sunil Khatri <sunil.khatri at amd.com>

Reviewed-by: Christian König <christian.koenig at amd.com>

> ---
>  drivers/gpu/drm/drm_debugfs.c | 80 +++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/drm_file.c    |  9 ++++
>  include/drm/drm_debugfs.h     | 11 +++++
>  include/drm/drm_file.h        |  7 +++
>  4 files changed, 107 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
> index 5807dd64d28a..ee79b694a750 100644
> --- a/drivers/gpu/drm/drm_debugfs.c
> +++ b/drivers/gpu/drm/drm_debugfs.c
> @@ -305,6 +305,86 @@ void drm_debugfs_remove_accel_root(void)
>  	debugfs_remove(accel_debugfs_root);
>  }
>  
> +static int drm_debugfs_proc_info_show(struct seq_file *m, void *unused)
> +{
> +	struct pid *pid;
> +	struct task_struct *task;
> +	struct drm_file *file = m->private;
> +
> +	if (!file)
> +		return -EINVAL;
> +
> +	rcu_read_lock();
> +	pid = rcu_dereference(file->pid);
> +	task = pid_task(pid, PIDTYPE_TGID);
> +
> +	seq_printf(m, "pid: %d\n", task ? task->pid : 0);
> +	seq_printf(m, "comm: %s\n", task ? task->comm : "Unset");
> +	rcu_read_unlock();
> +	return 0;
> +}
> +
> +static int drm_debufs_proc_info_open(struct inode *inode, struct file *file)
> +{
> +	return single_open(file, drm_debugfs_proc_info_show, inode->i_private);
> +}
> +
> +static const struct file_operations drm_debugfs_proc_info_fops = {
> +	.owner = THIS_MODULE,
> +	.open = drm_debufs_proc_info_open,
> +	.read = seq_read,
> +	.llseek = seq_lseek,
> +	.release = single_release,
> +};
> +
> +/**
> + * drm_debugfs_clients_add - Add a per client debugfs directory
> + * @file: drm_file for a client
> + *
> + * Create the debugfs directory for each client. This will be used to populate
> + * driver specific data for each client.
> + *
> + * Also add the process information debugfs file for each client to tag
> + * which client belongs to which process.
> + */
> +void drm_debugfs_clients_add(struct drm_file *file)
> +{
> +	char *client;
> +
> +	client = kasprintf(GFP_KERNEL, "client-%llu", file->client_id);
> +	if (!client)
> +		return;
> +
> +	/* Create a debugfs directory for the client in root on drm debugfs */
> +	file->debugfs_client = debugfs_create_dir(client, drm_debugfs_root);
> +	kfree(client);
> +
> +	debugfs_create_file("proc_info", 0444, file->debugfs_client, file,
> +			    &drm_debugfs_proc_info_fops);
> +
> +	client = kasprintf(GFP_KERNEL, "../%s", file->minor->dev->unique);
> +	if (!client)
> +		return;
> +
> +	/* Create a link from client_id to the drm device this client id belongs to */
> +	debugfs_create_symlink("device", file->debugfs_client, client);
> +	kfree(client);
> +}
> +
> +/**
> + * drm_debugfs_clients_remove - removes all debugfs directories and files
> + * @file: drm_file for a client
> + *
> + * Removes the debugfs directories recursively from the client directory.
> + *
> + * There is also a possibility that debugfs files are open while the drm_file
> + * is released.
> + */
> +void drm_debugfs_clients_remove(struct drm_file *file)
> +{
> +	debugfs_remove_recursive(file->debugfs_client);
> +	file->debugfs_client = NULL;
> +}
>  
>  /**
>   * drm_debugfs_dev_init - create debugfs directory for the device
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index 06ba6dcbf5ae..3f4c52d00540 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -45,6 +45,7 @@
>  #include <drm/drm_file.h>
>  #include <drm/drm_gem.h>
>  #include <drm/drm_print.h>
> +#include <drm/drm_debugfs.h>
>  
>  #include "drm_crtc_internal.h"
>  #include "drm_internal.h"
> @@ -167,6 +168,9 @@ struct drm_file *drm_file_alloc(struct drm_minor *minor)
>  
>  	drm_prime_init_file_private(&file->prime);
>  
> +	if (!drm_core_check_feature(dev, DRIVER_COMPUTE_ACCEL))
> +		drm_debugfs_clients_add(file);
> +
>  	if (dev->driver->open) {
>  		ret = dev->driver->open(dev, file);
>  		if (ret < 0)
> @@ -181,6 +185,8 @@ struct drm_file *drm_file_alloc(struct drm_minor *minor)
>  		drm_syncobj_release(file);
>  	if (drm_core_check_feature(dev, DRIVER_GEM))
>  		drm_gem_release(dev, file);
> +
> +	drm_debugfs_clients_remove(file);
>  	put_pid(rcu_access_pointer(file->pid));
>  	kfree(file);
>  
> @@ -235,6 +241,9 @@ void drm_file_free(struct drm_file *file)
>  		     (long)old_encode_dev(file->minor->kdev->devt),
>  		     atomic_read(&dev->open_count));
>  
> +	if (!drm_core_check_feature(dev, DRIVER_COMPUTE_ACCEL))
> +		drm_debugfs_clients_remove(file);
> +
>  	drm_events_release(file);
>  
>  	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
> diff --git a/include/drm/drm_debugfs.h b/include/drm/drm_debugfs.h
> index cf06cee4343f..ea8cba94208a 100644
> --- a/include/drm/drm_debugfs.h
> +++ b/include/drm/drm_debugfs.h
> @@ -153,6 +153,9 @@ void drm_debugfs_add_files(struct drm_device *dev,
>  
>  int drm_debugfs_gpuva_info(struct seq_file *m,
>  			   struct drm_gpuvm *gpuvm);
> +
> +void drm_debugfs_clients_add(struct drm_file *file);
> +void drm_debugfs_clients_remove(struct drm_file *file);
>  #else
>  static inline void drm_debugfs_create_files(const struct drm_info_list *files,
>  					    int count, struct dentry *root,
> @@ -181,6 +184,14 @@ static inline int drm_debugfs_gpuva_info(struct seq_file *m,
>  {
>  	return 0;
>  }
> +
> +static inline void drm_debugfs_clients_add(struct drm_file *file)
> +{
> +}
> +
> +static inline void drm_debugfs_clients_remove(struct drm_file *file)
> +{
> +}
>  #endif
>  
>  #endif /* _DRM_DEBUGFS_H_ */
> diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
> index 5c3b2aa3e69d..eab7546aad79 100644
> --- a/include/drm/drm_file.h
> +++ b/include/drm/drm_file.h
> @@ -400,6 +400,13 @@ struct drm_file {
>  	 * @client_name_lock: Protects @client_name.
>  	 */
>  	struct mutex client_name_lock;
> +
> +	/**
> +	 * @debugfs_client:
> +	 *
> +	 * debugfs directory for each client under a drm node.
> +	 */
> +	struct dentry *debugfs_client;
>  };
>  
>  /**