1 files changed, 38 insertions, 5 deletions

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index ff5b745c470..394523807a6 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -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;
@@ -481,12 +483,34 @@ 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);
-	return NULL;
+	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 +524,16 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
 	if (WARN_ON(!dmabuf))
 		return;
 
-	if (dmabuf->ops->vunmap)
-		dmabuf->ops->vunmap(dmabuf, vaddr);
+	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);