commit 96d4f43e3d012824f7e61920a340a1c03b6aacb0
author Steven Rostedt (Red Hat) <rostedt@goodmis.org> Wed Jun 25 10:27:30 2014 -0400
committer Steven Rostedt <rostedt@goodmis.org> Fri Jul 18 13:56:56 2014 -0400
tree 802730c1f8d56f7a68a32354d340d0cd609594ff
parent 3a46588e4b843afaa8f989fb494172d10e007afb

powerpc/ftrace: Add call to ftrace_graph_is_dead() in function graph code

ftrace_stop() is going away as it disables parts of function tracing
that affects users that should not be affected. But ftrace_graph_stop()
is built on ftrace_stop(). Here's another example of killing all of
function tracing because something went wrong with function graph
tracing.

Instead of disabling all users of function tracing on function graph
error, disable only function graph tracing. To do this, the arch code
must call ftrace_graph_is_dead() before it implements function graph.

Cc: Anton Blanchard <anton@samba.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

arch/powerpc/kernel/ftrace.c

diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index d178834..390311c 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -525,6 +525,9 @@
 	struct ftrace_graph_ent trace;
 	unsigned long return_hooker = (unsigned long)&return_to_handler;
 
+	if (unlikely(ftrace_graph_is_dead()))
+		return;
+
 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		return;