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Commit 3af4db15 authored by Liam Mark's avatar Liam Mark
Browse files

dma-buf: Add support to set a destructor on a dma-buf 



dma-buf destructor support is useful as it allows clients an opportunity
to undo any attributes, such as security attributes, they have applied to
the dma-buf's memory.

The destructor is called when the dma-buf is freed, if the destructor
returns an error the dma-buf's exporter release function is not called in
order to ensure that memory which has not been properly cleaned up isn't
returned to the system.

Change-Id: If2173b23b441157b3638110f02e2ff90ab6ad1aa
Signed-off-by: default avatarLiam Mark <lmark@codeaurora.org>
Signed-off-by: default avatarSwathi Sridhar <swatsrid@codeaurora.org>
parent f74ff626

drivers/dma-buf/dma-buf.c

+9 −1
Original line number Diff line number Diff line
@@ -69,6 +69,7 @@ static struct dma_buf_list db_list; 
static int dma_buf_release(struct inode *inode, struct file *file)

{

	struct dma_buf *dmabuf;

	int dtor_ret = 0;



	if (!is_dma_buf_file(file))

		return -EINVAL;
@@ -91,7 +92,14 @@ static int dma_buf_release(struct inode *inode, struct file *file) 
	list_del(&dmabuf->list_node);

	mutex_unlock(&db_list.lock);



	if (dmabuf->dtor)

		dtor_ret = dmabuf->dtor(dmabuf, dmabuf->dtor_data);



	if (!dtor_ret)

		dmabuf->ops->release(dmabuf);

	else

		pr_warn_ratelimited("Leaking dmabuf %s because destructor failed error:%d\n",

				    dmabuf->name, dtor_ret);



	dma_buf_ref_destroy(dmabuf);

include/linux/dma-buf.h

+28 −0
Original line number Diff line number Diff line
@@ -371,6 +371,18 @@ struct dma_buf_ops { 
	int (*get_flags)(struct dma_buf *dmabuf, unsigned long *flags);

};



/**

 * dma_buf_destructor - dma-buf destructor function

 * @dmabuf:	[in]	pointer to dma-buf

 * @dtor_data:	[in]	destructor data associated with this buffer

 *

 * The dma-buf destructor which is called when the dma-buf is freed.

 *

 * If the destructor returns an error the dma-buf's exporter release function

 * won't be called.

 */

typedef int (*dma_buf_destructor)(struct dma_buf *dmabuf, void *dtor_data);



/**

 * struct dma_buf - shared buffer object

 * @size: size of the buffer
@@ -428,6 +440,8 @@ struct dma_buf { 
	} cb_excl, cb_shared;



	struct list_head refs;

	dma_buf_destructor dtor;

	void *dtor_data;

};



/**
@@ -537,4 +551,18 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, 
void *dma_buf_vmap(struct dma_buf *);

void dma_buf_vunmap(struct dma_buf *, void *vaddr);

int dma_buf_get_flags(struct dma_buf *dma_buf, unsigned long *flags);



/**

 * dma_buf_set_destructor - set the dma-buf's destructor

 * @dmabuf:		[in]	pointer to dma-buf

 * @dma_buf_destructor	[in]	the destructor function

 * @dtor_data:		[in]	destructor data associated with this buffer

 */

static inline void dma_buf_set_destructor(struct dma_buf *dmabuf,

					  dma_buf_destructor dtor,

					  void *dtor_data)

{

	dmabuf->dtor = dtor;

	dmabuf->dtor_data = dtor_data;

}

#endif /* __DMA_BUF_H__ */