Hi Hans,
On (21/06/17 16:56), Sergey Senozhatsky wrote:
[..]
> static void *vb2_dc_vaddr(struct vb2_buffer *vb, void *buf_priv)
> {
> struct vb2_dc_buf *buf = buf_priv;
>
> if (buf->vaddr)
> return buf->vaddr;
>
> if (buf->db_attach) {
> struct dma_buf_map map;
>
> if (!dma_buf_vmap(buf->db_attach->dmabuf, &map))
> buf->vaddr = map.vaddr;
>
> return buf->vaddr;
> }
>
> if (!buf->coherent_mem)
> buf->vaddr = dma_vmap_noncontiguous(buf->dev, buf->size,
> buf->dma_sgt);
> return buf->vaddr;
> }
>
> And in vb2_dc_alloc functions set vaddr for !DMA_ATTR_NO_KERNEL_MAPPING
> in both coherent and non-coherent. So that we probably can have less
> branches when ->vaddr is NULL for one type of allocations, and is not
> NULL for another.
>
> static int vb2_dc_alloc_coherent(struct vb2_dc_buf *buf)
> {
> struct vb2_queue *q = buf->vb->vb2_queue;
>
> buf->cookie = dma_alloc_attrs(buf->dev,
> buf->size,
> &buf->dma_addr,
> GFP_KERNEL | q->gfp_flags,
> buf->attrs);
> if (!buf->cookie)
> return -ENOMEM;
>
> if (q->dma_attrs & DMA_ATTR_NO_KERNEL_MAPPING)
> return 0;
>
> buf->vaddr = buf->cookie;
> return 0;
> }
>
> static int vb2_dc_alloc_non_coherent(struct vb2_dc_buf *buf)
> {
> struct vb2_queue *q = buf->vb->vb2_queue;
>
> buf->dma_sgt = dma_alloc_noncontiguous(buf->dev,
> buf->size,
> buf->dma_dir,
> GFP_KERNEL | q->gfp_flags,
> buf->attrs);
> if (!buf->dma_sgt)
> return -ENOMEM;
>
> if (q->dma_attrs & DMA_ATTR_NO_KERNEL_MAPPING)
> return 0;
>
> buf->vaddr = dma_vmap_noncontiguous(buf->dev, buf->size, buf->dma_sgt);
> if (!buf->vaddr) {
> dma_free_noncontiguous(buf->dev, buf->size,
> buf->dma_sgt, buf->dma_addr);
> return -ENOMEM;
> }
> return 0;
> }
I guess this should address the case when
"after allocating the buffer, the buffer is exported as a dma_buf and
another device calls dma_buf_ops vb2_dc_dmabuf_ops_vmap, which in turn
calls dma_buf_map_set_vaddr(map, buf->vaddr); with a NULL buf->vaddr"
Because ->vaddr will not be NULL now after allocation for both coherent
and non-coherent buffers (modulo DMA_ATTR_NO_KERNEL_MAPPING requests).
What do you think?
