Hi,
On Fri, Oct 01, 2010 at 05:08:53AM +0200, ext Fernando Guzman Lugo wrote:
> As da_end does not belongs to the area the roundup should
> be done to da_end and not to da_end + 1.
> Also the end check for the last area should be
> ULONG_MAX - start + 1 >= bytes.
>
> Signed-off-by: Fernando Guzman Lugo <x0095840@xxxxxx>
> ---
> arch/arm/plat-omap/iovmm.c | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/plat-omap/iovmm.c b/arch/arm/plat-omap/iovmm.c
> index 24ca9c4..fc6b109 100644
> --- a/arch/arm/plat-omap/iovmm.c
> +++ b/arch/arm/plat-omap/iovmm.c
> @@ -289,19 +289,19 @@ static struct iovm_struct *alloc_iovm_area(struct iommu *obj, u32 da,
> prev_end = 0;
> list_for_each_entry(tmp, &obj->mmap, list) {
>
> - if (prev_end >= start)
> + if (prev_end > start)
> break;
>
> if (start + bytes <= tmp->da_start)
> goto found;
>
> if (flags & IOVMF_DA_ANON)
> - start = roundup(tmp->da_end + 1, alignement);
> + start = roundup(tmp->da_end, alignement);
There's a lack of comment here, but the purpose of tmp->da_end + 1 is to
create a gap between iovm areas to force to trigger iommu faults when
some access exceeds a valid area. Without this gap, such situation
may produce data corruption which is much more difficult to track.
Br,
David
>
> prev_end = tmp->da_end;
> }
>
> - if ((start > prev_end) && (ULONG_MAX - start >= bytes))
> + if ((start >= prev_end) && (ULONG_MAX - start + 1 >= bytes))
> goto found;
>
> dev_dbg(obj->dev, "%s: no space to fit %08x(%x) flags: %08x\n",
> --
> 1.6.3.3
>
> --
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