tracing: Fix infinite recursion in ftrace_update_pid_func()

When CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST is enabled
__ftrace_trace_function contains the current trace function, not
ftrace_trace_function.

In ftrace_update_pid_func() we currently incorrectly assign the
value of ftrace_trace_function to __ftrace_trace_funcion before
returning.

Without this patch it is possible to execute an infinite recursion
whereby ftrace_test_stop_func() calls __ftrace_trace_function,
which was assigned ftrace_test_stop_func() in
ftrace_update_pid_func().

Signed-off-by: Matt Fleming <[email protected]>
Acked-by: Steven Rostedt <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
LKML-Reference: <1254152581[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 46592feab5a6b0cf47e5cc147f43e1669efcf712..3724756e41ca9771d311101a38d2f408d416ef6a 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -225,7 +225,11 @@ static void ftrace_update_pid_func(void)
        if (ftrace_trace_function == ftrace_stub)
                return;
 
        if (ftrace_trace_function == ftrace_stub)
                return;
 

+#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST

        func = ftrace_trace_function;
        func = ftrace_trace_function;

+#else
+       func = __ftrace_trace_function;
+#endif

 
        if (ftrace_pid_trace) {
                set_ftrace_pid_function(func);
 
        if (ftrace_pid_trace) {
                set_ftrace_pid_function(func);