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tracing: Fix graph tracer with stack tracer on other archs 

Running my ftrace tests on PowerPC, it failed the test that checks
if function_graph tracer is affected by the stack tracer. It was.
Looking into this, I found that the update_function_graph_func()
must be called even if the trampoline function is not changed.
This is because archs like PowerPC do not support ftrace_ops being
passed by assembly and instead uses a helper function (what the
trampoline function points to). Since this function is not changed
even when multiple ftrace_ops are added to the code, the test that
falls out before calling update_function_graph_func() will miss that
the update must still be done.

Call update_function_graph_function() for all calls to
update_ftrace_function()

Cc: stable@vger.kernel.org # 3.3+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2014-07-15 11:05:12 -04:00 committed by Steven Rostedt
parent 8abfb8727f
commit 5f8bf2d263
1 changed files with 2 additions and 2 deletions
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4
kernel/trace/ftrace.c
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@ -265,12 +265,12 @@ static void update_ftrace_function(void)
func = ftrace_ops_list_func;
}
update_function_graph_func();
/* If there's no change, then do nothing more here */
if (ftrace_trace_function == func)
return;
update_function_graph_func();
/*
* If we are using the list function, it doesn't care
* about the function_trace_ops.