[XenPPC] [linux-ppc-2.6] [LINUX][POWERPC] Fix allocation error for xencomm "mini" descriptors.

[Xen patchbot-linux-ppc-2.6 <patchbot-linux-ppc-2.6@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Hollis Blanchard <hollisb@xxxxxxxxxx>
# Node ID cc44870e435343e40564f210e16d1141a314e593
# Parent  efefb3db340a70a34fd59435a260ebf4e6b8662d
[LINUX][POWERPC] Fix allocation error for xencomm "mini" descriptors.

Previous code worked correctly only if the allocated structure fit in the same
page as the base address. If the structure did not fit, the computation for the
allocation was incorrect. Noticed by Kiyokuni KAWACHIYA <KAWATIYA@xxxxxxxxxx>.

Signed-off-by: Maria Butrico <butrico@xxxxxxxxxxxxxx>
Signed-off-by: Hollis Blanchard <hollisb@xxxxxxxxxx>
---
 drivers/xen/core/xencomm.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff -r efefb3db340a -r cc44870e4353 drivers/xen/core/xencomm.c
--- a/drivers/xen/core/xencomm.c        Wed Sep 06 15:39:46 2006 -0500
+++ b/drivers/xen/core/xencomm.c        Fri Sep 08 10:17:30 2006 -0500
@@ -150,18 +150,18 @@ static void *xencomm_alloc_mini(void *ar
 static void *xencomm_alloc_mini(void *area, int arealen)
 {
        unsigned long base = (unsigned long)area;
-       unsigned int pageoffset;
+       unsigned int left_in_page;
 
-       pageoffset = base % PAGE_SIZE;
+       left_in_page = PAGE_SIZE - base % PAGE_SIZE;
 
        /* we probably fit right at the front of area */
-       if ((PAGE_SIZE - pageoffset) >= sizeof(struct xencomm_mini)) {
+       if (left_in_page >= sizeof(struct xencomm_mini)) {
                return area;
        }
 
        /* if not, see if area is big enough to advance to the next page */
-       if ((arealen - pageoffset) >= sizeof(struct xencomm_mini))
-               return (void *)(base + pageoffset);
+       if ((arealen - left_in_page) >= sizeof(struct xencomm_mini))
+               return (void *)(base + left_in_page);
 
        /* area was too small */
        return NULL;

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