[3.11.y.z extended stable] Patch "tracing: Fix graph tracer with stack tracer on other archs" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    tracing: Fix graph tracer with stack tracer on other archs

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From dc4f5444c69f3d100b846001f7ac04edcfc64490 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Red Hat)" <rostedt at goodmis.org>
Date: Tue, 15 Jul 2014 11:05:12 -0400
Subject: tracing: Fix graph tracer with stack tracer on other archs

commit 5f8bf2d263a20b986225ae1ed7d6759dc4b93af9 upstream.

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()

Signed-off-by: Steven Rostedt <rostedt at goodmis.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 kernel/trace/ftrace.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index df6bbd3d73ad..3aaae0661b21 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -331,12 +331,12 @@ 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.
--
1.9.1