From: Hiroshi DOYU <[email protected]> Subject: Re: [PATCHv7 9/9] ARM: dma-mapping: add support for IOMMU mapper Date: Wed, 07 Mar 2012 08:37:06 +0200 (EET) Message-ID: <[email protected]>
> From: Hiroshi DOYU <[email protected]> > Subject: Re: [PATCHv7 9/9] ARM: dma-mapping: add support for IOMMU mapper > Date: Wed, 07 Mar 2012 08:09:52 +0200 (EET) > Message-ID: <[email protected]> > > > From: Krishna Reddy <[email protected]> > > Subject: RE: [PATCHv7 9/9] ARM: dma-mapping: add support for IOMMU mapper > > Date: Tue, 6 Mar 2012 23:48:42 +0100 > > Message-ID: <[email protected]> > > > > > > > +struct dma_iommu_mapping * > > > > > +arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, > > > > > size_t size, > > > > > + int order) > > > > > +{ > > > > > + unsigned int count = (size >> PAGE_SHIFT) - order; > > > > > + unsigned int bitmap_size = BITS_TO_LONGS(count) * > > > > > sizeof(long); > > > > > > The count calculation doesn't seem correct. "order" is log2 number and > > > size >> PAGE_SHIFT is number of pages. > > > > > > If size is passed as 64*4096(256KB) and order is 6(allocation granularity > > > is 2^6 pages=256KB), > > > just 1 bit is enough to manage allocations. So it should be 4 bytes or > > > one long. > > > > Good catch! > > > > > But the calculation gives count = 64 - 6 = 58 and > > > Bitmap_size gets set to (58/(4*8)) * 4 = 8 bytes, which is incorrect. > > > > "order" isn't the order of size passed, which is minimal *page* > > allocation order which client decides whatever, just in case. > > > > > It should be as follows. > > > unsigned int count = 1 << get_order(size) - order; > > To be precise, as below? > > unsigned int count = 1 << (get_order(size) - order); This could be: >From fd40740ef4bc4a3924fe1188ea6dd785be0fe859 Mon Sep 17 00:00:00 2001 From: Hiroshi DOYU <[email protected]> Date: Wed, 7 Mar 2012 08:14:38 +0200 Subject: [PATCH 1/1] dma-mapping: Fix count calculation of iova space Fix count calculation of iova space. Pointed by Krishna Reddy <[email protected]> Signed-off-by: Hiroshi DOYU <[email protected]> --- arch/arm/mm/dma-mapping.c | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 6c2f104..56f0af5 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -1483,11 +1483,18 @@ struct dma_iommu_mapping * arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, size_t size, int order) { - unsigned int count = (size >> PAGE_SHIFT) - order; - unsigned int bitmap_size = BITS_TO_LONGS(count) * sizeof(long); + unsigned int n, count; + unsigned int bitmap_size; struct dma_iommu_mapping *mapping; int err = -ENOMEM; + n = get_order(size); + if (n < order) + return ERR_PTR(-EINVAL); + + count = 1 << (n - order); + bitmap_size = BITS_TO_LONGS(count) * sizeof(long); + mapping = kzalloc(sizeof(struct dma_iommu_mapping), GFP_KERNEL); if (!mapping) goto err; -- 1.7.5.4 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
