Merge tag 'tag-for-linus-3.9' of git://git.linaro.org/people/sumitsemwal/linux-dma-buf (5e04f4b4) · Commits · 戴 / test

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;
		};

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