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@xensource.com>

diff --git a/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c b/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c
index 471f5c76da0f491c452e0f5826355d3b4b159630..dcddf01ad77eed70e34a8785ec985ff06c3c1a96 100644 (file)
--- a/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c
+++ b/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c
@@ -75,6 +75,9 @@ DEFINE_SPINLOCK(balloon_lock);
 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 long nr_pages)
                .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 long nr_pages)
  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 long nr_pages)
                .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) {
@@ -331,9 +317,6 @@ static int decrease_reservation(unsigned long nr_pages)
 
        balloon_unlock(flags);
 
-       if (frame_list != &frame)
-               free_page((unsigned long)frame_list);
-
        return need_sleep;
 }