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| author | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2019-02-11 18:12:30 +0200 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2019-02-13 19:11:35 +0100 |
| commit | 70ca7ba2dbe4f1858b85e30269c8408a8bb8f272 (patch) | |
| tree | 7fd4f45e8a3beb5dbfe1f6fe078b4e4286235c80 /kernel/dma | |
| parent | 0a3b192c26da198fce38e1ee242a34f558670246 (diff) | |
| download | lwn-70ca7ba2dbe4f1858b85e30269c8408a8bb8f272.tar.gz lwn-70ca7ba2dbe4f1858b85e30269c8408a8bb8f272.zip | |
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>
Diffstat (limited to 'kernel/dma')
| -rw-r--r-- | kernel/dma/Kconfig | 36 |
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. |