[Xen-devel] [PATCH v2 3/3] mm: MEMF_node should handle changes in nodeid_t size

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

Instead of using a hardcoded constant to extract nodeID from
memflags use a macro whose value is based on nodeid_t size.

Also provide a macro for extracting nodeID from memflags so that
users don't need to remember to decrement the value.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
 xen/common/page_alloc.c |    2 +-
 xen/include/xen/mm.h    |    6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 124fa88..367b5bd 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -581,7 +581,7 @@ static struct page_info *alloc_heap_pages(
     struct domain *d)
 {
     unsigned int first_node, i, j, zone = 0, nodemask_retry = 0;
-    nodeid_t node = (nodeid_t)((memflags >> _MEMF_node) - 1);
+    nodeid_t node = MEMF2NODE(memflags);
     unsigned long request = 1UL << order;
     struct page_info *pg;
     nodemask_t nodemask = (d != NULL ) ? d->node_affinity : node_online_map;
diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index 74a65a6..c86c487 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -110,6 +110,8 @@ struct npfec {
 };
 
 /* memflags: */
+#define MEMF_node_mask    ((1U << sizeof(nodeid_t)) - 1)
+
 #define _MEMF_no_refcount 0
 #define  MEMF_no_refcount (1U<<_MEMF_no_refcount)
 #define _MEMF_populate_on_demand 1
@@ -121,10 +123,12 @@ struct npfec {
 #define _MEMF_exact_node  4
 #define  MEMF_exact_node  (1U<<_MEMF_exact_node)
 #define _MEMF_node        8
-#define  MEMF_node(n)     ((((n)+1)&0xff)<<_MEMF_node)
+#define  MEMF_node(n)     ((((n)+1) & MEMF_node_mask) << _MEMF_node)
 #define _MEMF_bits        24
 #define  MEMF_bits(n)     ((n)<<_MEMF_bits)
 
+#define MEMF2NODE(memflags) (MASK_EXTR(memflags, MEMF_node_mask) - 1)
+
 #ifdef CONFIG_PAGEALLOC_MAX_ORDER
 #define MAX_ORDER CONFIG_PAGEALLOC_MAX_ORDER
 #else
-- 
1.7.1


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