On 2019/1/3 6:36, Laura Abbott wrote:
On 12/24/18 12:19 AM, Qing Xia wrote:
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.
The problem is this subtly violates how dma_buf is supposed
to work. All setup is supposed to happen in begin_cpu_access.
I agree calling map kernel each time isn't great but I think
this needs to be worked out with dma_buf.
Thanks,
Laura
Thanks for your explanation.
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,
.
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