ftrace: add kernel command line graph function filtering

Add a command line parameter to allow limiting the function graphs
that are traced on boot up from the given top-level callers , when
ftrace=function_graph is specified.

This patch adds the following command line option:
ftrace_graph_filter=function-list

Where function-list is a comma separated list of functions to filter.

[fweisbec@gmail.com: picked the documentation changes from the v2 patch]

Signed-off-by: Stefan Assmann <sassmann@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4AD2DEB9.2@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 6fa7292947e5..1dc4b9cc20e5 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -778,6 +778,13 @@ and is between 256 and 4096 characters. It is defined in the file
                         by the set_ftrace_notrace file in the debugfs
                         tracing directory.
 
+        ftrace_graph_filter=[function-list]
+                        [FTRACE] Limit the top level callers functions traced
+                        by the function graph tracer at boot up.
+                        function-list is a comma separated list of functions
+                        that can be changed at run time by the
+                        set_graph_function file in the debugfs tracing directory.
+
         gamecon.map[2|3]=
                         [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
                         support via parallel port (up to 5 devices per port)