On 04/04/17 03:18, Sricharan R wrote: > Size of the dma-range is calculated as coherent_dma_mask + 1 > and passed to arch_setup_dma_ops further. It overflows when > the coherent_dma_mask is set for full 64 bits 0xFFFFFFFFFFFFFFFF, > resulting in size getting passed as 0 wrongly. Fix this by > passsing in max(mask, mask + 1). Note that in this case > when the mask is set to full 64bits, we will be passing the mask > itself to arch_setup_dma_ops instead of the size. The real fix > for this should be to make arch_setup_dma_ops receive the > mask and handle it, to be done in the future. > > Signed-off-by: Sricharan R <sricharan@xxxxxxxxxxxxxx> > --- > drivers/of/device.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/of/device.c b/drivers/of/device.c > index c17c19d..c2ae6bb 100644 > --- a/drivers/of/device.c > +++ b/drivers/of/device.c > @@ -107,7 +107,7 @@ void of_dma_configure(struct device *dev, struct device_node *np) > ret = of_dma_get_range(np, &dma_addr, &paddr, &size); > if (ret < 0) { > dma_addr = offset = 0; > - size = dev->coherent_dma_mask + 1; > + size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1); > } else { > offset = PFN_DOWN(paddr - dma_addr); > dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset); > NACK. Passing an invalid size to arch_setup_dma_ops() is only part of the problem. size is also used in of_dma_configure() before calling arch_setup_dma_ops(): dev->coherent_dma_mask = min(dev->coherent_dma_mask, DMA_BIT_MASK(ilog2(dma_addr + size))); *dev->dma_mask = min((*dev->dma_mask), DMA_BIT_MASK(ilog2(dma_addr + size))); which would be incorrect for size == 0xffffffffffffffffULL when dma_addr != 0. So the proposed fix really is not papering over the base problem very well. I agree that the proper solution involves passing a mask instead of a size to arch_setup_dma_ops(). -Frank -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html