ia64: export node_distance function

The numa_slit variable used by node_distance is available to a
module as long as it is linked at compile-time. However, it is
not available to loadable modules. Leading to errors such as:

  ERROR: "numa_slit" [drivers/nvme/host/nvme-core.ko] undefined!

The error above is caused by the nvme multipath code that makes
use of node_distance for its path calculation. When the patch was
added, the lightnvm subsystem would select nvme and always compile
it in, leading to the node_distance call to always succeed.
However, when this requirement was removed, nvme could be compiled
in as a module, which exposed this bug.

This patch extracts node_distance to a function and exports it.
Since ACPI is depending on node_distance being a simple lookup to
numa_slit, the previous behavior is exposed as slit_distance and its
users updated.

Fixes: f333444708f82 "nvme: take node locality into account when selecting a path"
Fixes: 73569e11032f "lightnvm: remove dependencies on BLK_DEV_NVME and PCI"
Signed-off-by: Matias Bjøring <mb@lightnvm.io>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/ia64/include/asm/numa.h b/arch/ia64/include/asm/numa.h
index ebef7f40aabb..c5c253cb9bd6 100644
--- a/arch/ia64/include/asm/numa.h
+++ b/arch/ia64/include/asm/numa.h
@@ -59,7 +59,9 @@ extern struct node_cpuid_s node_cpuid[NR_CPUS];
  */
 
 extern u8 numa_slit[MAX_NUMNODES * MAX_NUMNODES];
-#define node_distance(from,to) (numa_slit[(from) * MAX_NUMNODES + (to)])
+#define slit_distance(from,to) (numa_slit[(from) * MAX_NUMNODES + (to)])
+extern int __node_distance(int from, int to);
+#define node_distance(from,to) __node_distance(from, to)
 
 extern int paddr_to_nid(unsigned long paddr);