gdb/

* target.c (memory_xfer_partial): No need to restore shadows if we
	haven't read anything.

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2011-01-28  Pedro Alves  <pedro@codesourcery.com>
+
+	* target.c (memory_xfer_partial): No need to restore shadows if we
+	haven't read anything.
+
 2011-01-28  Pedro Alves  <pedro@codesourcery.com>
 
 	* mips-tdep.c (mips_print_register): Use get_frame_register_value

gdb/target.c

@@ -1414,7 +1414,7 @@ memory_xfer_partial (struct target_ops *ops, enum target_object object,
     }
   while (ops != NULL);
 
-  if (readbuf && !show_memory_breakpoints)
+  if (res > 0 && readbuf != NULL && !show_memory_breakpoints)
     breakpoint_restore_shadows (readbuf, memaddr, reg_len);
 
   /* Make sure the cache gets updated no matter what - if we are writing