[Xen-changelog] [xen-unstable] Use a static page for the frame_list in the balloon driver.

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

# HG changeset patch
# User shand@xxxxxxxxxxxxxxxxxxxxxxxx
# Node ID 9b35fada9e65417a72eae5cb7b7397b29cb8bdf1
# Parent  cb9443bfdff811619a94bebb5346ee74e936eee8
Use a static page for the frame_list in the balloon driver. 
Simplifies code and robustifies against oom situations. 

Signed-off-by: Steven Hand <steven@xxxxxxxxxxxxx>
---
 linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c |   35 +++++----------------
 1 files changed, 9 insertions(+), 26 deletions(-)

diff -r cb9443bfdff8 -r 9b35fada9e65 
linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c
--- a/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c        Thu Jun 29 
10:48:07 2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c        Thu Jun 29 
11:17:24 2006 +0100
@@ -75,6 +75,9 @@ static unsigned long current_pages;
 static unsigned long current_pages;
 static unsigned long target_pages;
 
+/* We increase/decrease in batches which fit in a page */
+static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)]; 
+
 /* VM /proc information for memory */
 extern unsigned long totalram_pages;
 
@@ -172,7 +175,7 @@ static unsigned long current_target(void
 
 static int increase_reservation(unsigned long nr_pages)
 {
-       unsigned long *frame_list, frame, pfn, i, flags;
+       unsigned long  pfn, i, flags;
        struct page   *page;
        long           rc;
        struct xen_memory_reservation reservation = {
@@ -181,15 +184,8 @@ static int increase_reservation(unsigned
                .domid        = DOMID_SELF
        };
 
-       if (nr_pages > (PAGE_SIZE / sizeof(unsigned long)))
-               nr_pages = PAGE_SIZE / sizeof(unsigned long);
-
-       frame_list = (unsigned long *)__get_free_page(GFP_KERNEL);
-       if (frame_list == NULL) {
-               frame_list = &frame;
-               if (nr_pages > 1)
-                       nr_pages = 1;
-       }
+       if (nr_pages > ARRAY_SIZE(frame_list))
+               nr_pages = ARRAY_SIZE(frame_list);
 
        balloon_lock(flags);
 
@@ -253,15 +249,12 @@ static int increase_reservation(unsigned
  out:
        balloon_unlock(flags);
 
-       if (frame_list != &frame)
-               free_page((unsigned long)frame_list);
-
        return 0;
 }
 
 static int decrease_reservation(unsigned long nr_pages)
 {
-       unsigned long *frame_list, frame, pfn, i, flags;
+       unsigned long  pfn, i, flags;
        struct page   *page;
        void          *v;
        int            need_sleep = 0;
@@ -272,15 +265,8 @@ static int decrease_reservation(unsigned
                .domid        = DOMID_SELF
        };
 
-       if (nr_pages > (PAGE_SIZE / sizeof(unsigned long)))
-               nr_pages = PAGE_SIZE / sizeof(unsigned long);
-
-       frame_list = (unsigned long *)__get_free_page(GFP_KERNEL);
-       if (frame_list == NULL) {
-               frame_list = &frame;
-               if (nr_pages > 1)
-                       nr_pages = 1;
-       }
+       if (nr_pages > ARRAY_SIZE(frame_list))
+               nr_pages = ARRAY_SIZE(frame_list);
 
        for (i = 0; i < nr_pages; i++) {
                if ((page = alloc_page(GFP_HIGHUSER)) == NULL) {
@@ -330,9 +316,6 @@ static int decrease_reservation(unsigned
        totalram_pages = current_pages;
 
        balloon_unlock(flags);
-
-       if (frame_list != &frame)
-               free_page((unsigned long)frame_list);
 
        return need_sleep;
 }

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