[Xen-changelog] [xen-unstable] [IA64] ia64 counter part of 19374:e655cb27d085.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
# Date 1238118848 -32400
# Node ID 5e4dd7079c484192e8621e64d817d58b995b4f75
# Parent  dee5bc89873e33641c5ad4f5ae3990e8a5ddc246
[IA64] ia64 counter part of 19374:e655cb27d085.

This patch is the ia64 counter part of 19374:e655cb27d085.

Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
---
 xen/include/asm-ia64/mm.h |   17 +++++++++++++----
 1 files changed, 13 insertions(+), 4 deletions(-)

diff -r dee5bc89873e -r 5e4dd7079c48 xen/include/asm-ia64/mm.h
--- a/xen/include/asm-ia64/mm.h Tue Mar 10 11:00:34 2009 +0900
+++ b/xen/include/asm-ia64/mm.h Fri Mar 27 10:54:08 2009 +0900
@@ -228,10 +228,18 @@ static inline struct domain *page_get_ow
 
     do {
         x = y;
-        if (unlikely((x & PGC_count_mask) == 0) ||  /* Not allocated? */
-            unlikely(((x + 1) & PGC_count_mask) == 0) ) {/* Count overflow? */
+        /*
+         * Count ==  0: Page is not allocated, so we cannot take a reference.
+         * Count == -1: Reference count would wrap, which is invalid.
+         * Count == -2: Remaining unused ref is reserved for get_page_light().
+         */
+        /*
+         * On ia64, get_page_light() isn't defined so that it doesn't
+         * make sense to take care of Count == -2.
+         * Just for consistency with x86.
+         */
+        if ( unlikely(((x + 2) & PGC_count_mask) <= 2) )
             return NULL;
-        }
         y = cmpxchg_acq(&page->count_info, x, x + 1);
     } while (unlikely(y != x));
 
@@ -247,7 +255,8 @@ static inline int get_page(struct page_i
     if (likely(owner == domain))
         return 1;
 
-    put_page(page);
+    if (owner != NULL)
+        put_page(page);
 
     /* if (!domain->is_dying) */ /* XXX: header inclusion hell */
     gdprintk(XENLOG_INFO,

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