On Thu, Jul 30, 2015 at 12:53:45PM -0400, Dan Williams wrote: > region_is_ram() is used to prevent the establishment of aliased mappings > to physical "System RAM" with incompatible cache settings. However, it > uses "-1" to indicate both "unknown" memory ranges (ranges not described > by platform firmware) and "mixed" ranges (where the parameters describe > a range that partially overlaps "System RAM"). > > Fix this up by explicitly tracking the "unknown" vs "mixed" resource > cases and returning REGION_INTERSECTS, REGION_MIXED, or REGION_DISJOINT. > This re-write also adds support for detecting when the requested region > completely eclipses all of a resource. Note, the implementation treats > overlaps between "unknown" and the requested memory type as > REGION_INTERSECTS. > > Finally, other memory types can be passed in by name, for now the only > usage "System RAM". > > Suggested-by: Luis R. Rodriguez <[email protected]> > Reviewed-by: Toshi Kani <[email protected]> > Signed-off-by: Dan Williams <[email protected]> > --- > include/linux/mm.h | 9 +++++++- > kernel/resource.c | 61 > +++++++++++++++++++++++++++++++--------------------- > 2 files changed, 44 insertions(+), 26 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 2e872f92dbac..84b05ebedb2d 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -369,7 +369,14 @@ static inline int put_page_unless_one(struct page *page) > } > > extern int page_is_ram(unsigned long pfn); > -extern int region_is_ram(resource_size_t phys_addr, unsigned long size); > + > +enum {
If you gave the enum a name, say enum region_intersect_type, you could then use that for the return type of region_intersects. > + REGION_INTERSECTS, > + REGION_DISJOINT, > + REGION_MIXED, > +}; > + > +int region_intersects(resource_size_t offset, size_t size, const char *type); If you used say a return type enum region_intersect_type, at compile time you'd get a complaint if any branch was not handled for the different enum types. Luis -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
