dma-mapping: move debug configuration options to kernel/dma

This is a follow up to the commit cf65a0f6f6ff

  ("dma-mapping: move all DMA mapping code to kernel/dma")

which moved source code of DMA API to kernel/dma folder. Since there is
no file left in the lib that require DMA API debugging options move the
latter to kernel/dma as well.

Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

1 files changed, 36 insertions, 0 deletions

diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
index ca88b867e7fe..61cebea36d89 100644
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -53,3 +53,39 @@ config DMA_REMAP
 config DMA_DIRECT_REMAP
         bool
         select DMA_REMAP
+
+config DMA_API_DEBUG
+        bool "Enable debugging of DMA-API usage"
+        select NEED_DMA_MAP_STATE
+        help
+          Enable this option to debug the use of the DMA API by device drivers.
+          With this option you will be able to detect common bugs in device
+          drivers like double-freeing of DMA mappings or freeing mappings that
+          were never allocated.
+
+          This also attempts to catch cases where a page owned by DMA is
+          accessed by the cpu in a way that could cause data corruption.  For
+          example, this enables cow_user_page() to check that the source page is
+          not undergoing DMA.
+
+          This option causes a performance degradation.  Use only if you want to
+          debug device drivers and dma interactions.
+
+          If unsure, say N.
+
+config DMA_API_DEBUG_SG
+        bool "Debug DMA scatter-gather usage"
+        default y
+        depends on DMA_API_DEBUG
+        help
+          Perform extra checking that callers of dma_map_sg() have respected the
+          appropriate segment length/boundary limits for the given device when
+          preparing DMA scatterlists.
+
+          This is particularly likely to have been overlooked in cases where the
+          dma_map_sg() API is used for general bulk mapping of pages rather than
+          preparing literal scatter-gather descriptors, where there is a risk of
+          unexpected behaviour from DMA API implementations if the scatterlist
+          is technically out-of-spec.
+
+          If unsure, say N.