1 files changed, 44 insertions, 0 deletions

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 89dcca448bb6..17972fbacddc 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -42,6 +42,7 @@
 #include <linux/io.h>
 #include <linux/delay.h>
 #include <linux/hardirq.h>
+#include <linux/workqueue.h>
 
 #include <xen/xen.h>
 #include <xen/interface/xen.h>
@@ -819,6 +820,49 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
 }
 EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
 
+#define GNTTAB_UNMAP_REFS_DELAY 5
+
+static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item);
+
+static void gnttab_unmap_work(struct work_struct *work)
+{
+        struct gntab_unmap_queue_data
+                *unmap_data = container_of(work, 
+                                           struct gntab_unmap_queue_data,
+                                           gnttab_work.work);
+        if (unmap_data->age != UINT_MAX)
+                unmap_data->age++;
+        __gnttab_unmap_refs_async(unmap_data);
+}
+
+static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
+{
+        int ret;
+        int pc;
+
+        for (pc = 0; pc < item->count; pc++) {
+                if (page_count(item->pages[pc]) > 1) {
+                        unsigned long delay = GNTTAB_UNMAP_REFS_DELAY * (item->age + 1);
+                        schedule_delayed_work(&item->gnttab_work,
+                                              msecs_to_jiffies(delay));
+                        return;
+                }
+        }
+
+        ret = gnttab_unmap_refs(item->unmap_ops, item->kunmap_ops,
+                                item->pages, item->count);
+        item->done(ret, item);
+}
+
+void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
+{
+        INIT_DELAYED_WORK(&item->gnttab_work, gnttab_unmap_work);
+        item->age = 0;
+
+        __gnttab_unmap_refs_async(item);
+}
+EXPORT_SYMBOL_GPL(gnttab_unmap_refs_async);
+
 static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
 {
         int rc;