[PATCH v10 09/13] x86/smpboot: add exit path for clone_mapping()

[Hongyan Xia <hx242@xxxxxxx>]

From: Wei Liu <wei.liu2@xxxxxxxxxx>

We will soon need to clean up page table mappings in the exit path.

No functional change.

Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
Signed-off-by: Hongyan Xia <hongyxia@xxxxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>

---
Changed in v7:
- edit commit message.
- begin with rc = 0 and set it to -ENOMEM ahead of if().
---
 xen/arch/x86/smpboot.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index 82c1012e892f..e90c4dfa8a88 100644
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -696,6 +696,7 @@ static int clone_mapping(const void *ptr, root_pgentry_t 
*rpt)
     l3_pgentry_t *pl3e;
     l2_pgentry_t *pl2e;
     l1_pgentry_t *pl1e;
+    int rc = 0;
 
     /*
      * Sanity check 'linear'.  We only allow cloning from the Xen virtual
@@ -736,7 +737,7 @@ static int clone_mapping(const void *ptr, root_pgentry_t 
*rpt)
             pl1e = l2e_to_l1e(*pl2e) + l1_table_offset(linear);
             flags = l1e_get_flags(*pl1e);
             if ( !(flags & _PAGE_PRESENT) )
-                return 0;
+                goto out;
             pfn = l1e_get_pfn(*pl1e);
         }
     }
@@ -744,8 +745,9 @@ static int clone_mapping(const void *ptr, root_pgentry_t 
*rpt)
     if ( !(root_get_flags(rpt[root_table_offset(linear)]) & _PAGE_PRESENT) )
     {
         pl3e = alloc_xen_pagetable();
+        rc = -ENOMEM;
         if ( !pl3e )
-            return -ENOMEM;
+            goto out;
         clear_page(pl3e);
         l4e_write(&rpt[root_table_offset(linear)],
                   l4e_from_paddr(__pa(pl3e), __PAGE_HYPERVISOR));
@@ -758,8 +760,9 @@ static int clone_mapping(const void *ptr, root_pgentry_t 
*rpt)
     if ( !(l3e_get_flags(*pl3e) & _PAGE_PRESENT) )
     {
         pl2e = alloc_xen_pagetable();
+        rc = -ENOMEM;
         if ( !pl2e )
-            return -ENOMEM;
+            goto out;
         clear_page(pl2e);
         l3e_write(pl3e, l3e_from_paddr(__pa(pl2e), __PAGE_HYPERVISOR));
     }
@@ -774,8 +777,9 @@ static int clone_mapping(const void *ptr, root_pgentry_t 
*rpt)
     if ( !(l2e_get_flags(*pl2e) & _PAGE_PRESENT) )
     {
         pl1e = alloc_xen_pagetable();
+        rc = -ENOMEM;
         if ( !pl1e )
-            return -ENOMEM;
+            goto out;
         clear_page(pl1e);
         l2e_write(pl2e, l2e_from_paddr(__pa(pl1e), __PAGE_HYPERVISOR));
     }
@@ -796,7 +800,9 @@ static int clone_mapping(const void *ptr, root_pgentry_t 
*rpt)
     else
         l1e_write(pl1e, l1e_from_pfn(pfn, flags));
 
-    return 0;
+    rc = 0;
+ out:
+    return rc;
 }
 
 DEFINE_PER_CPU(root_pgentry_t *, root_pgt);
-- 
2.23.4