ftrace: enable trace_printk by default

Impact: have the ftrace_printk enabled on startup

It is confusing to have to "echo trace_printk > /debug/tracing/iter_ctrl"
after adding ftrace_printk in the kernel.

Currently the trace_printk is set to off by default. ftrace_printk
should only be in open kernel code when used for debugging, and thus
it should be enabled by default.

It may also be used to record data within a tracer, but those ftrace_printks
should be within wrappers that are either enabled by trace_points or
have a variable protecting the code path from being entered when the
tracer is disabled.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d55ccfc8d67451abfedadbe606a095774447260e..dbbdacfaaf9ece6a2bbbd15b541fdf1e0e8a804e 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -205,7 +205,7 @@ static DEFINE_MUTEX(trace_types_lock);
 static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
 
 /* trace_flags holds iter_ctrl options */
-unsigned long trace_flags = TRACE_ITER_PRINT_PARENT;
+unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK;
 
 /**
  * trace_wake_up - wake up tasks waiting for trace input