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Commit 5e04f4b4 authored by Linus Torvalds's avatar Linus Torvalds
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Merge tag 'tag-for-linus-3.9' of git://git.linaro.org/people/sumitsemwal/linux-dma-buf 

Pull dma-buf framework updates from Sumit Semwal:
 "Refcounting implemented for vmap in core dma-buf"

* tag 'tag-for-linus-3.9' of git://git.linaro.org/people/sumitsemwal/linux-dma-buf:
  CHROMIUM: dma-buf: restore args on failure of dma_buf_mmap
  dma-buf: implement vmap refcounting in the interface logic
parents b6669737 495c10cc

Documentation/dma-buf-sharing.txt

+5 −1
Original line number Diff line number Diff line
@@ -302,7 +302,11 @@ Access to a dma_buf from the kernel context involves three steps: 
      void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)



   The vmap call can fail if there is no vmap support in the exporter, or if it

   runs out of vmalloc space. Fallback to kmap should be implemented.

   runs out of vmalloc space. Fallback to kmap should be implemented. Note that

   the dma-buf layer keeps a reference count for all vmap access and calls down

   into the exporter's vmap function only when no vmapping exists, and only

   unmaps it once. Protection against concurrent vmap/vunmap calls is provided

   by taking the dma_buf->lock mutex.



3. Finish access

drivers/base/dma-buf.c

+55 −11
Original line number Diff line number Diff line
@@ -39,6 +39,8 @@ static int dma_buf_release(struct inode *inode, struct file *file) 


	dmabuf = file->private_data;



	BUG_ON(dmabuf->vmapping_counter);



	dmabuf->ops->release(dmabuf);

	kfree(dmabuf);

	return 0;
@@ -445,6 +447,9 @@ EXPORT_SYMBOL_GPL(dma_buf_kunmap); 
int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,

		 unsigned long pgoff)

{

	struct file *oldfile;

	int ret;



	if (WARN_ON(!dmabuf || !vma))

		return -EINVAL;
@@ -458,14 +463,22 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, 
		return -EINVAL;



	/* readjust the vma */

	if (vma->vm_file)

		fput(vma->vm_file);



	vma->vm_file = get_file(dmabuf->file);



	get_file(dmabuf->file);

	oldfile = vma->vm_file;

	vma->vm_file = dmabuf->file;

	vma->vm_pgoff = pgoff;



	return dmabuf->ops->mmap(dmabuf, vma);

	ret = dmabuf->ops->mmap(dmabuf, vma);

	if (ret) {

		/* restore old parameters on failure */

		vma->vm_file = oldfile;

		fput(dmabuf->file);

	} else {

		if (oldfile)

			fput(oldfile);

	}

	return ret;



}

EXPORT_SYMBOL_GPL(dma_buf_mmap);
@@ -481,12 +494,34 @@ EXPORT_SYMBOL_GPL(dma_buf_mmap); 
 */

void *dma_buf_vmap(struct dma_buf *dmabuf)

{

	void *ptr;



	if (WARN_ON(!dmabuf))

		return NULL;



	if (dmabuf->ops->vmap)

		return dmabuf->ops->vmap(dmabuf);

	if (!dmabuf->ops->vmap)

		return NULL;



	mutex_lock(&dmabuf->lock);

	if (dmabuf->vmapping_counter) {

		dmabuf->vmapping_counter++;

		BUG_ON(!dmabuf->vmap_ptr);

		ptr = dmabuf->vmap_ptr;

		goto out_unlock;

	}



	BUG_ON(dmabuf->vmap_ptr);



	ptr = dmabuf->ops->vmap(dmabuf);

	if (IS_ERR_OR_NULL(ptr))

		goto out_unlock;



	dmabuf->vmap_ptr = ptr;

	dmabuf->vmapping_counter = 1;



out_unlock:

	mutex_unlock(&dmabuf->lock);

	return ptr;

}

EXPORT_SYMBOL_GPL(dma_buf_vmap);
@@ -500,7 +535,16 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr) 
	if (WARN_ON(!dmabuf))

		return;



	BUG_ON(!dmabuf->vmap_ptr);

	BUG_ON(dmabuf->vmapping_counter == 0);

	BUG_ON(dmabuf->vmap_ptr != vaddr);



	mutex_lock(&dmabuf->lock);

	if (--dmabuf->vmapping_counter == 0) {

		if (dmabuf->ops->vunmap)

			dmabuf->ops->vunmap(dmabuf, vaddr);

		dmabuf->vmap_ptr = NULL;

	}

	mutex_unlock(&dmabuf->lock);

}

EXPORT_SYMBOL_GPL(dma_buf_vunmap);

include/linux/dma-buf.h

+3 −1
Original line number Diff line number Diff line
@@ -119,8 +119,10 @@ struct dma_buf { 
	struct file *file;

	struct list_head attachments;

	const struct dma_buf_ops *ops;

	/* mutex to serialize list manipulation and attach/detach */

	/* mutex to serialize list manipulation, attach/detach and vmap/unmap */

	struct mutex lock;

	unsigned vmapping_counter;

	void *vmap_ptr;

	void *priv;

};