Using just the filter for checking for trampolines or regs is not enough
when updating the code against the records that represent all functions.
Both the filter hash and the notrace hash need to be checked.

To trigger this bug (using trace-cmd and perf):

 # perf probe -a do_fork
 # trace-cmd start -B foo -e probe
 # trace-cmd record -p function_graph -n do_fork sleep 1

The trace-cmd record at the end clears the filter before it disables
function_graph tracing and then that causes the accounting of the
ftrace function records to become incorrect and causes ftrace to bug.

Link: http://lkml.kernel.org/r/20150114154329.358378039@goodmis.org

Cc: stable@vger.kernel.org
[ still need to switch old_hash_ops to old_ops_hash ]
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>