On Thu, Sep 27, 2018 at 09:22:02AM -0500, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
>
> find_next_iomem_res() finds an iomem resource that covers part of a range
> described by "start, end". All callers expect that range to be inclusive,
> i.e., both start and end are included, but find_next_iomem_res() doesn't
> handle the end address correctly.
>
> If it finds an iomem resource that contains exactly the end address, it
> skips it, e.g., if "start, end" is [0x0-0x10000] and there happens to be an
> iomem resource [mem 0x10000-0x10000] (the single byte at 0x10000), we skip
> it:
>
> find_next_iomem_res(...)
> {
> start = 0x0;
> end = 0x10000;
> for (p = next_resource(...)) {
> # p->start = 0x10000;
> # p->end = 0x10000;
> # we *should* return this resource, but this condition is false:
> if ((p->end >= start) && (p->start < end))
> break;
>
> Adjust find_next_iomem_res() so it allows a resource that includes the
> single byte at the end of the range. This is a corner case that we
> probably don't see in practice.
This is how one should write commit messages! Thanks for that - it was a
joy - for a change - to read it :-)
>
> Fixes: 58c1b5b07907 ("[PATCH] memory hotadd fixes: find_next_system_ram catch range fix")
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> ---
> kernel/resource.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
> diff --git a/kernel/resource.c b/kernel/resource.c
> index 30e1bc68503b..155ec873ea4d 100644
> --- a/kernel/resource.c
> +++ b/kernel/resource.c
> @@ -319,7 +319,7 @@ int release_resource(struct resource *old)
> EXPORT_SYMBOL(release_resource);
>
> /*
> - * Finds the lowest iomem resource existing within [res->start.res->end).
What I'm still wondering about is, why was it ever even considered to
have a non-inclusive range. Looking at the git history, especially
58c1b5b07907 and 2842f11419704 - it looks like it was an omission and
then users started using it with inclusive ranges.
Thx.
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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