[PATCH 01/16] media: videobuf-dma-contig: use dma_mmap_coherent

Christoph Hellwig
2019-06-14T13:47:47Z

dma_alloc_coherent does not return a physical address, but a DMA
address, which might be remapped or have an offset. Passing this
DMA address to vm_iomap_memory is completely bogus. Use the proper
dma_mmap_coherent helper instead, and stop passing __GFP_COMP
to dma_alloc_coherent, as the memory management inside the DMA
allocator is hidden from the callers.

Fixes: a8f3c203e19b ("[media] videobuf-dma-contig: add cache support")
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/media/v4l2-core/videobuf-dma-contig.c | 23 +++++++------------
1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf-dma-contig.c b/drivers/media/v4l2-core/videobuf-dma-contig.c
index e1bf50df4c70..a5942ea38f1f 100644
--- a/drivers/media/v4l2-core/videobuf-dma-contig.c
+++ b/drivers/media/v4l2-core/videobuf-dma-contig.c
@@ -39,11 +39,11 @@ struct videobuf_dma_contig_memory {

static int __videobuf_dc_alloc(struct device *dev,
struct videobuf_dma_contig_memory *mem,
- unsigned long size, gfp_t flags)
+ unsigned long size)
{
mem->size = size;
- mem->vaddr = dma_alloc_coherent(dev, mem->size,
- &mem->dma_handle, flags);
+ mem->vaddr = dma_alloc_coherent(dev, mem->size, &mem->dma_handle,
+ GFP_KERNEL);

if (!mem->vaddr) {
dev_err(dev, "memory alloc size %ld failed\n", mem->size);
@@ -260,8 +260,7 @@ static int __videobuf_iolock(struct videobuf_queue *q,
return videobuf_dma_contig_user_get(mem, vb);

/* allocate memory for the read() method */
- if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(vb->size),
- GFP_KERNEL))
+ if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(vb->size)))
return -ENOMEM;
break;
case V4L2_MEMORY_OVERLAY:
@@ -280,7 +279,6 @@ static int __videobuf_mmap_mapper(struct videobuf_queue *q,
struct videobuf_dma_contig_memory *mem;
struct videobuf_mapping *map;
int retval;
- unsigned long size;

dev_dbg(q->dev, "%s\n", __func__);

@@ -298,23 +296,18 @@ static int __videobuf_mmap_mapper(struct videobuf_queue *q,
BUG_ON(!mem);
MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);

- if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(buf->bsize),
- GFP_KERNEL | __GFP_COMP))
+ if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(buf->bsize)))
goto error;

- /* Try to remap memory */
- size = vma->vm_end - vma->vm_start;
- vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
-
/* the "vm_pgoff" is just used in v4l2 to find the
* corresponding buffer data structure which is allocated
* earlier and it does not mean the offset from the physical
* buffer start address as usual. So set it to 0 to pass
- * the sanity check in vm_iomap_memory().
+ * the sanity check in dma_mmap_coherent().
*/
vma->vm_pgoff = 0;
-
- retval = vm_iomap_memory(vma, mem->dma_handle, size);
+ retval = dma_mmap_coherent(q->dev, vma, mem->vaddr, mem->dma_handle,
+ vma->vm_end - vma->vm_start);
if (retval) {
dev_err(q->dev, "mmap: remap failed with error %d. ",
retval);
--
2.20.1