ftrace: separate out the function enabled variable
Currently the function tracer uses the global tracer_enabled variable that
is used to keep track if the tracer is enabled or not. The function tracing
startup needs to be separated out, otherwise the internal happenings of
the tracer startup is also recorded.
This patch creates a ftrace_function_enabled variable to all the starting
of the function traces to happen after everything has been started.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f8fdb9c..2e37857 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -96,6 +96,9 @@
/* tracer_enabled is used to toggle activation of a tracer */
static int tracer_enabled = 1;
+/* function tracing enabled */
+int ftrace_function_enabled;
+
/*
* trace_nr_entries is the number of entries that is allocated
* for a buffer. Note, the number of entries is always rounded
@@ -134,6 +137,7 @@
{
int cpu;
+ ftrace_function_enabled = 0;
if(tr->ctrl)
for_each_online_cpu(cpu)
tracing_reset(tr->data[cpu]);
@@ -985,7 +989,7 @@
long disabled;
int cpu;
- if (unlikely(!tracer_enabled))
+ if (unlikely(!ftrace_function_enabled))
return;
if (skip_trace(ip))
@@ -1010,11 +1014,15 @@
void tracing_start_function_trace(void)
{
+ ftrace_function_enabled = 0;
register_ftrace_function(&trace_ops);
+ if (tracer_enabled)
+ ftrace_function_enabled = 1;
}
void tracing_stop_function_trace(void)
{
+ ftrace_function_enabled = 0;
unregister_ftrace_function(&trace_ops);
}
#endif
@@ -1850,8 +1858,10 @@
m->private = iter;
/* stop the trace while dumping */
- if (iter->tr->ctrl)
+ if (iter->tr->ctrl) {
tracer_enabled = 0;
+ ftrace_function_enabled = 0;
+ }
if (iter->trace && iter->trace->open)
iter->trace->open(iter);
@@ -1884,8 +1894,14 @@
iter->trace->close(iter);
/* reenable tracing if it was previously enabled */
- if (iter->tr->ctrl)
+ if (iter->tr->ctrl) {
tracer_enabled = 1;
+ /*
+ * It is safe to enable function tracing even if it
+ * isn't used
+ */
+ ftrace_function_enabled = 1;
+ }
mutex_unlock(&trace_types_lock);
seq_release(inode, file);