[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....@hisilicon.com>
---
 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