Re: [PATCH 8/8] xen/gntdev: Expose gntdev's dma-buf API for in-kernel use

[Oleksandr Andrushchenko <andr2000@gmail.com>]

On 05/25/2018 06:33 PM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>
> Allow creating grant device context for use by kernel modules which
> require functionality, provided by gntdev. Export symbols for dma-buf
> API provided by the module.
>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> ---
>   drivers/xen/gntdev.c    | 116 ++++++++++++++++++++++++++--------------
>   include/xen/grant_dev.h |  37 +++++++++++++
>   2 files changed, 113 insertions(+), 40 deletions(-)
>   create mode 100644 include/xen/grant_dev.h
>
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index d8b6168f2cd9..912056f3e909 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -684,14 +684,33 @@ static const struct mmu_notifier_ops gntdev_mmu_ops = {
>   
>   /* ------------------------------------------------------------------ */
>   
> -static int gntdev_open(struct inode *inode, struct file *flip)
> +void gntdev_free_context(struct gntdev_priv *priv)
> +{
> +	struct grant_map *map;
> +
> +	pr_debug("priv %p\n", priv);
> +
> +	mutex_lock(&priv->lock);
> +	while (!list_empty(&priv->maps)) {
> +		map = list_entry(priv->maps.next, struct grant_map, next);
> +		list_del(&map->next);
> +		gntdev_put_map(NULL /* already removed */, map);
> +	}
> +	WARN_ON(!list_empty(&priv->freeable_maps));
> +
> +	mutex_unlock(&priv->lock);
> +
> +	kfree(priv);
> +}
> +EXPORT_SYMBOL(gntdev_free_context);
I will convert EXPORT_SYMBOL to EXPORT_SYMBOL_GPL here and below
> +
> +struct gntdev_priv *gntdev_alloc_context(struct device *dev)
>   {
>   	struct gntdev_priv *priv;
> -	int ret = 0;
>   
>   	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
>   	if (!priv)
> -		return -ENOMEM;
> +		return ERR_PTR(-ENOMEM);
>   
>   	INIT_LIST_HEAD(&priv->maps);
>   	INIT_LIST_HEAD(&priv->freeable_maps);
> @@ -704,6 +723,32 @@ static int gntdev_open(struct inode *inode, struct file *flip)
>   	INIT_LIST_HEAD(&priv->dmabuf_imp_list);
>   #endif
>   
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> +	priv->dma_dev = dev;
> +
> +	/*
> +	 * The device is not spawn from a device tree, so arch_setup_dma_ops
> +	 * is not called, thus leaving the device with dummy DMA ops.
> +	 * Fix this call of_dma_configure() with a NULL node to set
> +	 * default DMA ops.
> +	 */
> +	of_dma_configure(priv->dma_dev, NULL);
> +#endif
> +	pr_debug("priv %p\n", priv);
> +
> +	return priv;
> +}
> +EXPORT_SYMBOL(gntdev_alloc_context);
> +
> +static int gntdev_open(struct inode *inode, struct file *flip)
> +{
> +	struct gntdev_priv *priv;
> +	int ret = 0;
> +
> +	priv = gntdev_alloc_context(gntdev_miscdev.this_device);
> +	if (IS_ERR(priv))
> +		return PTR_ERR(priv);
> +
>   	if (use_ptemod) {
>   		priv->mm = get_task_mm(current);
>   		if (!priv->mm) {
> @@ -716,23 +761,11 @@ static int gntdev_open(struct inode *inode, struct file *flip)
>   	}
>   
>   	if (ret) {
> -		kfree(priv);
> +		gntdev_free_context(priv);
>   		return ret;
>   	}
>   
>   	flip->private_data = priv;
> -#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> -	priv->dma_dev = gntdev_miscdev.this_device;
> -
> -	/*
> -	 * The device is not spawn from a device tree, so arch_setup_dma_ops
> -	 * is not called, thus leaving the device with dummy DMA ops.
> -	 * Fix this call of_dma_configure() with a NULL node to set
> -	 * default DMA ops.
> -	 */
> -	of_dma_configure(priv->dma_dev, NULL);
> -#endif
> -	pr_debug("priv %p\n", priv);
>   
>   	return 0;
>   }
> @@ -740,22 +773,11 @@ static int gntdev_open(struct inode *inode, struct file *flip)
>   static int gntdev_release(struct inode *inode, struct file *flip)
>   {
>   	struct gntdev_priv *priv = flip->private_data;
> -	struct grant_map *map;
> -
> -	pr_debug("priv %p\n", priv);
> -
> -	mutex_lock(&priv->lock);
> -	while (!list_empty(&priv->maps)) {
> -		map = list_entry(priv->maps.next, struct grant_map, next);
> -		list_del(&map->next);
> -		gntdev_put_map(NULL /* already removed */, map);
> -	}
> -	WARN_ON(!list_empty(&priv->freeable_maps));
> -	mutex_unlock(&priv->lock);
>   
>   	if (use_ptemod)
>   		mmu_notifier_unregister(&priv->mn, priv->mm);
> -	kfree(priv);
> +
> +	gntdev_free_context(priv);
>   	return 0;
>   }
>   
> @@ -1210,7 +1232,7 @@ dmabuf_exp_wait_obj_get_by_fd(struct gntdev_priv *priv, int fd)
>   	return ret;
>   }
>   
> -static int dmabuf_exp_wait_released(struct gntdev_priv *priv, int fd,
> +int gntdev_dmabuf_exp_wait_released(struct gntdev_priv *priv, int fd,
>   				    int wait_to_ms)
>   {
>   	struct xen_dmabuf *xen_dmabuf;
> @@ -1242,6 +1264,7 @@ static int dmabuf_exp_wait_released(struct gntdev_priv *priv, int fd,
>   	dmabuf_exp_wait_obj_free(priv, obj);
>   	return ret;
>   }
> +EXPORT_SYMBOL(gntdev_dmabuf_exp_wait_released);
>   
>   /* ------------------------------------------------------------------ */
>   /* DMA buffer export support.                                         */
> @@ -1511,7 +1534,7 @@ dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
>   	return map;
>   }
>   
> -static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
> +int gntdev_dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
>   				int count, u32 domid, u32 *refs, u32 *fd)
>   {
>   	struct grant_map *map;
> @@ -1557,6 +1580,7 @@ static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
>   	gntdev_remove_map(priv, map);
>   	return ret;
>   }
> +EXPORT_SYMBOL(gntdev_dmabuf_exp_from_refs);
>   
>   /* ------------------------------------------------------------------ */
>   /* DMA buffer import support.                                         */
> @@ -1646,8 +1670,9 @@ static struct xen_dmabuf *dmabuf_imp_alloc_storage(int count)
>   	return ERR_PTR(-ENOMEM);
>   }
>   
> -static struct xen_dmabuf *
> -dmabuf_imp_to_refs(struct gntdev_priv *priv, int fd, int count, int domid)
> +struct xen_dmabuf *
> +gntdev_dmabuf_imp_to_refs(struct gntdev_priv *priv, int fd,
> +			  int count, int domid)
>   {
>   	struct xen_dmabuf *xen_dmabuf, *ret;
>   	struct dma_buf *dma_buf;
> @@ -1736,6 +1761,16 @@ dmabuf_imp_to_refs(struct gntdev_priv *priv, int fd, int count, int domid)
>   	dma_buf_put(dma_buf);
>   	return ret;
>   }
> +EXPORT_SYMBOL(gntdev_dmabuf_imp_to_refs);
> +
> +u32 *gntdev_dmabuf_imp_get_refs(struct xen_dmabuf *xen_dmabuf)
> +{
> +	if (xen_dmabuf)
> +		return xen_dmabuf->u.imp.refs;
> +
> +	return NULL;
> +}
> +EXPORT_SYMBOL(gntdev_dmabuf_imp_get_refs);
>   
>   /*
>    * Find the hyper dma-buf by its file descriptor and remove
> @@ -1759,7 +1794,7 @@ dmabuf_imp_find_unlink(struct gntdev_priv *priv, int fd)
>   	return ret;
>   }
>   
> -static int dmabuf_imp_release(struct gntdev_priv *priv, u32 fd)
> +int gntdev_dmabuf_imp_release(struct gntdev_priv *priv, u32 fd)
>   {
>   	struct xen_dmabuf *xen_dmabuf;
>   	struct dma_buf_attachment *attach;
> @@ -1785,6 +1820,7 @@ static int dmabuf_imp_release(struct gntdev_priv *priv, u32 fd)
>   	dmabuf_imp_free_storage(xen_dmabuf);
>   	return 0;
>   }
> +EXPORT_SYMBOL(gntdev_dmabuf_imp_release);
>   
>   /* ------------------------------------------------------------------ */
>   /* DMA buffer IOCTL support.                                          */
> @@ -1810,8 +1846,8 @@ gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv,
>   		goto out;
>   	}
>   
> -	ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
> -				   op.domid, refs, &op.fd);
> +	ret = gntdev_dmabuf_exp_from_refs(priv, op.flags, op.count,
> +					  op.domid, refs, &op.fd);
>   	if (ret)
>   		goto out;
>   
> @@ -1832,7 +1868,7 @@ gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
>   	if (copy_from_user(&op, u, sizeof(op)) != 0)
>   		return -EFAULT;
>   
> -	return dmabuf_exp_wait_released(priv, op.fd, op.wait_to_ms);
> +	return gntdev_dmabuf_exp_wait_released(priv, op.fd, op.wait_to_ms);
>   }
>   
>   static long
> @@ -1846,7 +1882,7 @@ gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
>   	if (copy_from_user(&op, u, sizeof(op)) != 0)
>   		return -EFAULT;
>   
> -	xen_dmabuf = dmabuf_imp_to_refs(priv, op.fd, op.count, op.domid);
> +	xen_dmabuf = gntdev_dmabuf_imp_to_refs(priv, op.fd, op.count, op.domid);
>   	if (IS_ERR(xen_dmabuf))
>   		return PTR_ERR(xen_dmabuf);
>   
> @@ -1858,7 +1894,7 @@ gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
>   	return 0;
>   
>   out_release:
> -	dmabuf_imp_release(priv, op.fd);
> +	gntdev_dmabuf_imp_release(priv, op.fd);
>   	return ret;
>   }
>   
> @@ -1871,7 +1907,7 @@ gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
>   	if (copy_from_user(&op, u, sizeof(op)) != 0)
>   		return -EFAULT;
>   
> -	return dmabuf_imp_release(priv, op.fd);
> +	return gntdev_dmabuf_imp_release(priv, op.fd);
>   }
>   #endif
>   
> diff --git a/include/xen/grant_dev.h b/include/xen/grant_dev.h
> new file mode 100644
> index 000000000000..faccc9170174
> --- /dev/null
> +++ b/include/xen/grant_dev.h
> @@ -0,0 +1,37 @@
> +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
> +
> +/*
> + * Grant device kernel API
> + *
> + * Copyright (C) 2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#ifndef _GRANT_DEV_H
> +#define _GRANT_DEV_H
> +
> +#include <linux/types.h>
> +
> +struct device;
> +struct gntdev_priv;
> +#ifdef CONFIG_XEN_GNTDEV_DMABUF
> +struct xen_dmabuf;
> +#endif
> +
> +struct gntdev_priv *gntdev_alloc_context(struct device *dev);
> +void gntdev_free_context(struct gntdev_priv *priv);
> +
> +#ifdef CONFIG_XEN_GNTDEV_DMABUF
> +int gntdev_dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
> +				int count, u32 domid, u32 *refs, u32 *fd);
> +int gntdev_dmabuf_exp_wait_released(struct gntdev_priv *priv, int fd,
> +				    int wait_to_ms);
> +
> +struct xen_dmabuf *gntdev_dmabuf_imp_to_refs(struct gntdev_priv *priv,
> +					     int fd, int count, int domid);
> +u32 *gntdev_dmabuf_imp_get_refs(struct xen_dmabuf *xen_dmabuf);
> +int gntdev_dmabuf_imp_release(struct gntdev_priv *priv, u32 fd);
> +#endif
> +
> +#endif