ftrace: Allow to remove a single function from function graph filter

I don't see why we can only clear all functions from the filter.

After patching:

  # echo sys_open > set_graph_function
  # echo sys_close >> set_graph_function
  # cat set_graph_function
  sys_open
  sys_close
  # echo '!sys_close' >> set_graph_function
  # cat set_graph_function
  sys_open

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4B726388.2000408@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index ce077fbbf552..b477fce41edf 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -497,6 +497,7 @@ trace_print_graph_duration(unsigned long long duration, struct trace_seq *s);
 #ifdef CONFIG_DYNAMIC_FTRACE
 /* TODO: make this variable */
 #define FTRACE_GRAPH_MAX_FUNCS          32
+extern int ftrace_graph_filter_enabled;
 extern int ftrace_graph_count;
 extern unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS];
 
@@ -504,7 +505,7 @@ static inline int ftrace_graph_addr(unsigned long addr)
 {
         int i;
 
-        if (!ftrace_graph_count)
+        if (!ftrace_graph_filter_enabled)
                 return 1;
 
         for (i = 0; i < ftrace_graph_count; i++) {