[PATCH] staging: android: ion: move map_kernel to ion_dma_buf_kmap

[Qing Xia]

Now, as Google's user guide, if userspace need clean ION buffer's
cache, they should call ioctl(fd, DMA_BUF_IOCTL_SYNC, sync). Then
we found that ion_dma_buf_begin_cpu_access/ion_dma_buf_end_cpu_access
will do ION buffer's map_kernel, it's not necessary. And if usersapce
only need clean cache, they will call ion_dma_buf_end_cpu_access by
dmabuf's ioctl, ION buffer's kmap_cnt will be wrong value -1, then
driver could not get right kernel vaddr by dma_buf_kmap.

Signed-off-by: Qing Xia <saberlily.xia@xxxxxxxxxxxxx>
---
 drivers/staging/android/ion/ion.c | 46 ++++++++++++++++++---------------------
 1 file changed, 21 insertions(+), 25 deletions(-)

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 9907332..f7e2812 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -303,45 +303,47 @@ static void ion_dma_buf_release(struct dma_buf *dmabuf)
 static void *ion_dma_buf_kmap(struct dma_buf *dmabuf, unsigned long offset)
 {
 	struct ion_buffer *buffer = dmabuf->priv;
+	void *vaddr;
 
-	return buffer->vaddr + offset * PAGE_SIZE;
+	if (buffer->heap->ops->map_kernel) {
+		mutex_lock(&buffer->lock);
+		vaddr = ion_buffer_kmap_get(buffer);
+		mutex_unlock(&buffer->lock);
+		if (IS_ERR(vaddr))
+			return vaddr;
+
+		return vaddr + offset * PAGE_SIZE;
+	}
+
+	return NULL;
 }
 
 static void ion_dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long offset,
 			       void *ptr)
 {
+	struct ion_buffer *buffer = dmabuf->priv;
+
+	if (buffer->heap->ops->map_kernel) {
+		mutex_lock(&buffer->lock);
+		ion_buffer_kmap_put(buffer);
+		mutex_unlock(&buffer->lock);
+	}
 }
 
 static int ion_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
 					enum dma_data_direction direction)
 {
 	struct ion_buffer *buffer = dmabuf->priv;
-	void *vaddr;
 	struct ion_dma_buf_attachment *a;
-	int ret = 0;
-
-	/*
-	 * TODO: Move this elsewhere because we don't always need a vaddr
-	 */
-	if (buffer->heap->ops->map_kernel) {
-		mutex_lock(&buffer->lock);
-		vaddr = ion_buffer_kmap_get(buffer);
-		if (IS_ERR(vaddr)) {
-			ret = PTR_ERR(vaddr);
-			goto unlock;
-		}
-		mutex_unlock(&buffer->lock);
-	}
 
 	mutex_lock(&buffer->lock);
 	list_for_each_entry(a, &buffer->attachments, list) {
 		dma_sync_sg_for_cpu(a->dev, a->table->sgl, a->table->nents,
 				    direction);
 	}
-
-unlock:
 	mutex_unlock(&buffer->lock);
-	return ret;
+
+	return 0;
 }
 
 static int ion_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
@@ -350,12 +352,6 @@ static int ion_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
 	struct ion_buffer *buffer = dmabuf->priv;
 	struct ion_dma_buf_attachment *a;
 
-	if (buffer->heap->ops->map_kernel) {
-		mutex_lock(&buffer->lock);
-		ion_buffer_kmap_put(buffer);
-		mutex_unlock(&buffer->lock);
-	}
-
 	mutex_lock(&buffer->lock);
 	list_for_each_entry(a, &buffer->attachments, list) {
 		dma_sync_sg_for_device(a->dev, a->table->sgl, a->table->nents,
-- 
2.7.3