From 70ca7ba2dbe4f1858b85e30269c8408a8bb8f272 Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Mon, 11 Feb 2019 18:12:30 +0200 Subject: 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 Signed-off-by: Andy Shevchenko Signed-off-by: Christoph Hellwig --- kernel/dma/Kconfig | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) (limited to 'kernel/dma') 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. -- cgit