Re: [RFC v2 1/8] drm: provide management functions for drm_file

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Jan 03, 2018 at 11:21:03PM +0100, Noralf Trønnes wrote:
> From: David Herrmann <dh.herrmann@gmail.com>
> 
> Rather than doing drm_file allocation/destruction right in the fops, lets
> provide separate helpers. This decouples drm_file management from the
> still-mandatory drm-fops. It prepares for use of drm_file without the
> fops, both by possible separate fops implementations and APIs (not that I
> am aware of any such plans), and more importantly from in-kernel use where
> no real file is available.
> 
> Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
> [rebased]
> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> ---
>  drivers/gpu/drm/drm_file.c     | 309 +++++++++++++++++++++++------------------
>  drivers/gpu/drm/drm_internal.h |   2 +
>  2 files changed, 179 insertions(+), 132 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index b3c6e997ccdb..d208faade27e 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -101,6 +101,179 @@ DEFINE_MUTEX(drm_global_mutex);
>  
>  static int drm_open_helper(struct file *filp, struct drm_minor *minor);
>  
> +/**
> + * drm_file_alloc - allocate file context
> + * @minor: minor to allocate on
> + *
> + * This allocates a new DRM file context. It is not linked into any context and
> + * can be used by the caller freely. Note that the context keeps a pointer to
> + * @minor, so it must be freed before @minor is.
> + *
> + * The legacy paths might require the drm_global_mutex to be held.

I'd remove this line, since it's only relevant to close the driver load
vs. file open race for drivers still using the deprecated ->load callback.
This only confuses and doesn't help anyone writing a new/modern driver.

> + *
> + * RETURNS:
> + * Pointer to newly allocated context, ERR_PTR on failure.
> + */
> +struct drm_file *drm_file_alloc(struct drm_minor *minor)
> +{
> +	struct drm_device *dev = minor->dev;
> +	struct drm_file *file;
> +	int ret;
> +
> +	file = kzalloc(sizeof(*file), GFP_KERNEL);
> +	if (!file)
> +		return ERR_PTR(-ENOMEM);
> +
> +	file->pid = get_pid(task_pid(current));
> +	file->minor = minor;
> +
> +	/* for compatibility root is always authenticated */
> +	file->authenticated = capable(CAP_SYS_ADMIN);
> +	file->lock_count = 0;
> +
> +	INIT_LIST_HEAD(&file->lhead);
> +	INIT_LIST_HEAD(&file->fbs);
> +	mutex_init(&file->fbs_lock);
> +	INIT_LIST_HEAD(&file->blobs);
> +	INIT_LIST_HEAD(&file->pending_event_list);
> +	INIT_LIST_HEAD(&file->event_list);
> +	init_waitqueue_head(&file->event_wait);
> +	file->event_space = 4096; /* set aside 4k for event buffer */
> +
> +	mutex_init(&file->event_read_lock);
> +
> +	if (drm_core_check_feature(dev, DRIVER_GEM))
> +		drm_gem_open(dev, file);
> +
> +	if (drm_core_check_feature(dev, DRIVER_SYNCOBJ))
> +		drm_syncobj_open(file);
> +
> +	if (drm_core_check_feature(dev, DRIVER_PRIME))
> +		drm_prime_init_file_private(&file->prime);
> +
> +	if (dev->driver->open) {
> +		ret = dev->driver->open(dev, file);
> +		if (ret < 0)
> +			goto out_prime_destroy;
> +	}
> +
> +	if (drm_is_primary_client(file)) {
> +		ret = drm_master_open(file);
> +		if (ret)
> +			goto out_close;
> +	}
> +
> +	return file;
> +
> +out_close:
> +	if (dev->driver->postclose)
> +		dev->driver->postclose(dev, file);
> +out_prime_destroy:
> +	if (drm_core_check_feature(dev, DRIVER_PRIME))
> +		drm_prime_destroy_file_private(&file->prime);
> +	if (drm_core_check_feature(dev, DRIVER_SYNCOBJ))
> +		drm_syncobj_release(file);
> +	if (drm_core_check_feature(dev, DRIVER_GEM))
> +		drm_gem_release(dev, file);
> +	put_pid(file->pid);
> +	kfree(file);
> +
> +	return ERR_PTR(ret);
> +}
> +
> +static void drm_events_release(struct drm_file *file_priv)
> +{
> +	struct drm_device *dev = file_priv->minor->dev;
> +	struct drm_pending_event *e, *et;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dev->event_lock, flags);
> +
> +	/* Unlink pending events */
> +	list_for_each_entry_safe(e, et, &file_priv->pending_event_list,
> +				 pending_link) {
> +		list_del(&e->pending_link);
> +		e->file_priv = NULL;
> +	}
> +
> +	/* Remove unconsumed events */
> +	list_for_each_entry_safe(e, et, &file_priv->event_list, link) {
> +		list_del(&e->link);
> +		kfree(e);
> +	}
> +
> +	spin_unlock_irqrestore(&dev->event_lock, flags);
> +}
> +
> +/**
> + * drm_file_free - free file context
> + * @file: context to free, or NULL
> + *
> + * This destroys and deallocates a DRM file context previously allocated via
> + * drm_file_alloc(). The caller must make sure to unlink it from any contexts
> + * before calling this.
> + *
> + * The legacy paths might require the drm_global_mutex to be held.

Same here.

With the bikesheds address and maybe the EXPORT_SYMBOL for these from
patch 3 moved to here:

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>


> + *
> + * If NULL is passed, this is a no-op.
> + *
> + * RETURNS:
> + * 0 on success, or error code on failure.
> + */
> +void drm_file_free(struct drm_file *file)
> +{
> +	struct drm_device *dev;
> +
> +	if (!file)
> +		return;
> +
> +	dev = file->minor->dev;
> +
> +	DRM_DEBUG("pid = %d, device = 0x%lx, open_count = %d\n",
> +		  task_pid_nr(current),
> +		  (long)old_encode_dev(file->minor->kdev->devt),
> +		  dev->open_count);
> +
> +	if (drm_core_check_feature(dev, DRIVER_LEGACY) &&
> +	    dev->driver->preclose)
> +		dev->driver->preclose(dev, file);
> +
> +	if (drm_core_check_feature(dev, DRIVER_LEGACY))
> +		drm_legacy_lock_release(dev, file->filp);
> +
> +	if (drm_core_check_feature(dev, DRIVER_HAVE_DMA))
> +		drm_legacy_reclaim_buffers(dev, file);
> +
> +	drm_events_release(file);
> +
> +	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
> +		drm_fb_release(file);
> +		drm_property_destroy_user_blobs(dev, file);
> +	}
> +
> +	if (drm_core_check_feature(dev, DRIVER_SYNCOBJ))
> +		drm_syncobj_release(file);
> +
> +	if (drm_core_check_feature(dev, DRIVER_GEM))
> +		drm_gem_release(dev, file);
> +
> +	drm_legacy_ctxbitmap_flush(dev, file);
> +
> +	if (drm_is_primary_client(file))
> +		drm_master_release(file);
> +
> +	if (dev->driver->postclose)
> +		dev->driver->postclose(dev, file);
> +
> +	if (drm_core_check_feature(dev, DRIVER_PRIME))
> +		drm_prime_destroy_file_private(&file->prime);
> +
> +	WARN_ON(!list_empty(&file->event_list));
> +
> +	put_pid(file->pid);
> +	kfree(file);
> +}
> +
>  static int drm_setup(struct drm_device * dev)
>  {
>  	int ret;
> @@ -196,7 +369,6 @@ static int drm_open_helper(struct file *filp, struct drm_minor *minor)
>  {
>  	struct drm_device *dev = minor->dev;
>  	struct drm_file *priv;
> -	int ret;
>  
>  	if (filp->f_flags & O_EXCL)
>  		return -EBUSY;	/* No exclusive opens */
> @@ -207,50 +379,12 @@ static int drm_open_helper(struct file *filp, struct drm_minor *minor)
>  
>  	DRM_DEBUG("pid = %d, minor = %d\n", task_pid_nr(current), minor->index);
>  
> -	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> -	if (!priv)
> -		return -ENOMEM;
> +	priv = drm_file_alloc(minor);
> +	if (IS_ERR(priv))
> +		return PTR_ERR(priv);
>  
>  	filp->private_data = priv;
>  	priv->filp = filp;
> -	priv->pid = get_pid(task_pid(current));
> -	priv->minor = minor;
> -
> -	/* for compatibility root is always authenticated */
> -	priv->authenticated = capable(CAP_SYS_ADMIN);
> -	priv->lock_count = 0;
> -
> -	INIT_LIST_HEAD(&priv->lhead);
> -	INIT_LIST_HEAD(&priv->fbs);
> -	mutex_init(&priv->fbs_lock);
> -	INIT_LIST_HEAD(&priv->blobs);
> -	INIT_LIST_HEAD(&priv->pending_event_list);
> -	INIT_LIST_HEAD(&priv->event_list);
> -	init_waitqueue_head(&priv->event_wait);
> -	priv->event_space = 4096; /* set aside 4k for event buffer */
> -
> -	mutex_init(&priv->event_read_lock);
> -
> -	if (drm_core_check_feature(dev, DRIVER_GEM))
> -		drm_gem_open(dev, priv);
> -
> -	if (drm_core_check_feature(dev, DRIVER_SYNCOBJ))
> -		drm_syncobj_open(priv);
> -
> -	if (drm_core_check_feature(dev, DRIVER_PRIME))
> -		drm_prime_init_file_private(&priv->prime);
> -
> -	if (dev->driver->open) {
> -		ret = dev->driver->open(dev, priv);
> -		if (ret < 0)
> -			goto out_prime_destroy;
> -	}
> -
> -	if (drm_is_primary_client(priv)) {
> -		ret = drm_master_open(priv);
> -		if (ret)
> -			goto out_close;
> -	}
>  
>  	mutex_lock(&dev->filelist_mutex);
>  	list_add(&priv->lhead, &dev->filelist);
> @@ -277,45 +411,6 @@ static int drm_open_helper(struct file *filp, struct drm_minor *minor)
>  #endif
>  
>  	return 0;
> -
> -out_close:
> -	if (dev->driver->postclose)
> -		dev->driver->postclose(dev, priv);
> -out_prime_destroy:
> -	if (drm_core_check_feature(dev, DRIVER_PRIME))
> -		drm_prime_destroy_file_private(&priv->prime);
> -	if (drm_core_check_feature(dev, DRIVER_SYNCOBJ))
> -		drm_syncobj_release(priv);
> -	if (drm_core_check_feature(dev, DRIVER_GEM))
> -		drm_gem_release(dev, priv);
> -	put_pid(priv->pid);
> -	kfree(priv);
> -	filp->private_data = NULL;
> -	return ret;
> -}
> -
> -static void drm_events_release(struct drm_file *file_priv)
> -{
> -	struct drm_device *dev = file_priv->minor->dev;
> -	struct drm_pending_event *e, *et;
> -	unsigned long flags;
> -
> -	spin_lock_irqsave(&dev->event_lock, flags);
> -
> -	/* Unlink pending events */
> -	list_for_each_entry_safe(e, et, &file_priv->pending_event_list,
> -				 pending_link) {
> -		list_del(&e->pending_link);
> -		e->file_priv = NULL;
> -	}
> -
> -	/* Remove unconsumed events */
> -	list_for_each_entry_safe(e, et, &file_priv->event_list, link) {
> -		list_del(&e->link);
> -		kfree(e);
> -	}
> -
> -	spin_unlock_irqrestore(&dev->event_lock, flags);
>  }
>  
>  static void drm_legacy_dev_reinit(struct drm_device *dev)
> @@ -382,57 +477,7 @@ int drm_release(struct inode *inode, struct file *filp)
>  	list_del(&file_priv->lhead);
>  	mutex_unlock(&dev->filelist_mutex);
>  
> -	if (drm_core_check_feature(dev, DRIVER_LEGACY) &&
> -	    dev->driver->preclose)
> -		dev->driver->preclose(dev, file_priv);
> -
> -	/* ========================================================
> -	 * Begin inline drm_release
> -	 */
> -
> -	DRM_DEBUG("pid = %d, device = 0x%lx, open_count = %d\n",
> -		  task_pid_nr(current),
> -		  (long)old_encode_dev(file_priv->minor->kdev->devt),
> -		  dev->open_count);
> -
> -	if (drm_core_check_feature(dev, DRIVER_LEGACY))
> -		drm_legacy_lock_release(dev, filp);
> -
> -	if (drm_core_check_feature(dev, DRIVER_HAVE_DMA))
> -		drm_legacy_reclaim_buffers(dev, file_priv);
> -
> -	drm_events_release(file_priv);
> -
> -	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
> -		drm_fb_release(file_priv);
> -		drm_property_destroy_user_blobs(dev, file_priv);
> -	}
> -
> -	if (drm_core_check_feature(dev, DRIVER_SYNCOBJ))
> -		drm_syncobj_release(file_priv);
> -
> -	if (drm_core_check_feature(dev, DRIVER_GEM))
> -		drm_gem_release(dev, file_priv);
> -
> -	drm_legacy_ctxbitmap_flush(dev, file_priv);
> -
> -	if (drm_is_primary_client(file_priv))
> -		drm_master_release(file_priv);
> -
> -	if (dev->driver->postclose)
> -		dev->driver->postclose(dev, file_priv);
> -
> -	if (drm_core_check_feature(dev, DRIVER_PRIME))
> -		drm_prime_destroy_file_private(&file_priv->prime);
> -
> -	WARN_ON(!list_empty(&file_priv->event_list));
> -
> -	put_pid(file_priv->pid);
> -	kfree(file_priv);
> -
> -	/* ========================================================
> -	 * End inline drm_release
> -	 */
> +	drm_file_free(file_priv);
>  
>  	if (!--dev->open_count) {
>  		drm_lastclose(dev);
> diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
> index b72242e93ea4..40179c5fc6b8 100644
> --- a/drivers/gpu/drm/drm_internal.h
> +++ b/drivers/gpu/drm/drm_internal.h
> @@ -26,6 +26,8 @@
>  
>  /* drm_file.c */
>  extern struct mutex drm_global_mutex;
> +struct drm_file *drm_file_alloc(struct drm_minor *minor);
> +void drm_file_free(struct drm_file *file);
>  void drm_lastclose(struct drm_device *dev);
>  
>  /* drm_pci.c */
> -- 
> 2.14.2
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel