libxc/restore: introduce setup() and cleanup() on restore

introduce setup() and cleanup() which subsume the
ctx->restore.ops.{setup,cleanup}() calls and also
do memory alloc/free.

Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
CC: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Ian Campbell <Ian.Campbell@citrix.com>
CC: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>

tools/libxc/xc_sr_restore.c

@@ -510,6 +510,38 @@ static int process_record(struct xc_sr_context *ctx, struct xc_sr_record *rec)
     return rc;
 }
 
+static int setup(struct xc_sr_context *ctx)
+{
+    xc_interface *xch = ctx->xch;
+    int rc;
+
+    rc = ctx->restore.ops.setup(ctx);
+    if ( rc )
+        goto err;
+
+    ctx->restore.max_populated_pfn = (32 * 1024 / 4) - 1;
+    ctx->restore.populated_pfns = bitmap_alloc(
+        ctx->restore.max_populated_pfn + 1);
+    if ( !ctx->restore.populated_pfns )
+    {
+        ERROR("Unable to allocate memory for populated_pfns bitmap");
+        rc = -1;
+        goto err;
+    }
+
+ err:
+    return rc;
+}
+
+static void cleanup(struct xc_sr_context *ctx)
+{
+    xc_interface *xch = ctx->xch;
+
+    free(ctx->restore.populated_pfns);
+    if ( ctx->restore.ops.cleanup(ctx) )
+        PERROR("Failed to clean up");
+}
+
 #ifdef XG_LIBXL_HVM_COMPAT
 extern int read_qemu(struct xc_sr_context *ctx);
 #endif
@@ -524,19 +556,10 @@ static int restore(struct xc_sr_context *ctx)
 
     IPRINTF("Restoring domain");
 
-    rc = ctx->restore.ops.setup(ctx);
+    rc = setup(ctx);
     if ( rc )
         goto err;
 
-    ctx->restore.max_populated_pfn = (32 * 1024 / 4) - 1;
-    ctx->restore.populated_pfns = bitmap_alloc(
-        ctx->restore.max_populated_pfn + 1);
-    if ( !ctx->restore.populated_pfns )
-    {
-        ERROR("Unable to allocate memory for populated_pfns bitmap");
-        goto err;
-    }
-
     do
     {
         rc = read_record(ctx, &rec);
@@ -571,10 +594,7 @@ static int restore(struct xc_sr_context *ctx)
     PERROR("Restore failed");
 
  done:
-    free(ctx->restore.populated_pfns);
-    rc = ctx->restore.ops.cleanup(ctx);
-    if ( rc )
-        PERROR("Failed to clean up");
+    cleanup(ctx);
 
     if ( saved_rc )
     {