File 19490-log-dirty.patch of Package xen

# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1238590175 -3600
# Node ID 2491158ccd173786590340cbcf77985f66cd2b8f
# Parent  01873414cfc13f6682210551b8fb3cb1b77bb2dd
x86: paging_log_dirty_op() should take care with invalid log_dirty.top

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1238655191 -3600
# Node ID 6dc5c26a75b90b04e7ed73cebd4643897f26c7c7
# Parent  b5e7c26835c9fc2e9c26e27478a938e36f98d645
x86: A further fix to paging_log_dirty_op() -- do not unmap_domain_page(NULL)

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

--- a/xen/arch/x86/mm/paging.c
+++ b/xen/arch/x86/mm/paging.c
@@ -385,13 +385,14 @@ int paging_log_dirty_op(struct domain *d
     }
 
     pages = 0;
-    l4 = map_domain_page(mfn_x(d->arch.paging.log_dirty.top));
+    l4 = (mfn_valid(d->arch.paging.log_dirty.top) ?
+          map_domain_page(mfn_x(d->arch.paging.log_dirty.top)) : NULL);
 
     for ( i4 = 0;
           (pages < sc->pages) && (i4 < LOGDIRTY_NODE_ENTRIES);
           i4++ )
     {
-        l3 = mfn_valid(l4[i4]) ? map_domain_page(mfn_x(l4[i4])) : NULL;
+        l3 = (l4 && mfn_valid(l4[i4])) ? map_domain_page(mfn_x(l4[i4])) : NULL;
         for ( i3 = 0;
               (pages < sc->pages) && (i3 < LOGDIRTY_NODE_ENTRIES);
               i3++ )
@@ -429,7 +430,8 @@ int paging_log_dirty_op(struct domain *d
         if ( l3 )
             unmap_domain_page(l3);
     }
-    unmap_domain_page(l4);
+    if ( l4 )
+        unmap_domain_page(l4);
 
     if ( pages < sc->pages )
         sc->pages = pages;