[PATCH] dma-coherent: Clarify dma_mmap_from_dev_coherent documentation

[PATCH] dma-coherent: Clarify dma_mmap_from_dev_coherent documentation

[Robin Murphy]

The use of "correctly mapped" here is misleading, since it can give the
wrong expectation in the case that the memory *should* have been mapped
from the per-device pool, but doing so failed for other reasons.

Signed-off-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
---
 drivers/base/dma-coherent.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index 1e6396bb807b..597d40893862 100644
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -312,8 +312,9 @@ static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem,
  * This checks whether the memory was allocated from the per-device
  * coherent memory pool and if so, maps that memory to the provided vma.
  *
- * Returns 1 if we correctly mapped the memory, or 0 if the caller should
- * proceed with mapping memory from generic pools.
+ * Returns 1 if @vaddr belongs to the device coherent pool and the caller
+ * should return @ret, or 0 if they should proceed with mapping memory from
+ * generic areas.
  */
 int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
 			   void *vaddr, size_t size, int *ret)
-- 
2.16.1.dirty

Re: [PATCH] dma-coherent: Clarify dma_mmap_from_dev_coherent documentation

[Christoph Hellwig]

On Mon, Apr 09, 2018 at 06:59:14PM +0100, Robin Murphy wrote:
> The use of "correctly mapped" here is misleading, since it can give the
> wrong expectation in the case that the memory *should* have been mapped
> from the per-device pool, but doing so failed for other reasons.

Thanks,

applied to the dma-mapping tree for 4.17.