Messages in this thread Patch in this message |  | | From | Vitaly Kuzmichev <> | Subject | [PATCH v2 1/2] drivers: dma-coherent: Fix dev->cma_area vs dev->dma_mem breakage | Date | Fri, 7 Jul 2017 16:22:59 +0300 |
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From: "George G. Davis" <george_davis@mentor.com>
When a "linux,dma-default" DMA coherent region is defined, the dma_coherent_default_memory pointer is returned by function dev_get_coherent_memory() for any struct device *dev which has not explicitly assigned a dev->dma_mem memory region, i.e. dev->dma_mem is the NULL pointer. Unfortunately this overlooks the fact that for the CONFIG_DMA_CMA case, it is also possible that a device may have assigned a CMA memory region via the dev->cma_area pointer in which case, the "linux,dma-default" DMA coherent region should not be used. Since the current code did not consider this case, dev->cma_area regions are not used when a "linux,dma-default" DMA coherent region is defined. Instead, memory is allocated from the "linux,dma-default" DMA coherent region. This omission could lead to DMA memory allocation failures for devices such as the "viv,galcore" which require a large contiguous address space which cannot be supplied by the "linux,dma-default" region IFF it has been reconfigured to use a CMA memory region. Similar DMA allocation failures are likely to occur for other devices which require large memory regions and/or overall allocation requests exceed the size of the "linux,dma-default" DMA coherent region size.
Fix this by updating the dev_get_coherent_memory() function to return the NULL pointer if a dev->cma_area region is assigned to a device.
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Robin Murphy <robin.murphy@arm.com> Signed-off-by: George G. Davis <george_davis@mentor.com> Signed-off-by: Vitaly Kuzmichev <vitaly_kuzmichev@mentor.com> --- drivers/base/dma-coherent.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c index 2ae24c2..acfe140 100644 --- a/drivers/base/dma-coherent.c +++ b/drivers/base/dma-coherent.c @@ -25,6 +25,10 @@ static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *de { if (dev && dev->dma_mem) return dev->dma_mem; +#ifdef CONFIG_DMA_CMA + if (dev && dev->cma_area) + return NULL; +#endif return dma_coherent_default_memory; } -- 1.9.1
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