Messages in this thread | | | Date | Sat, 19 Jun 2021 11:22:02 -0400 | From | Steven Rostedt <> | Subject | Re: [RFC PATCH 1/2] ftrace: Introduce cmdline argument ftrace_disabled |
| |
On Sat, 19 Jun 2021 14:29:19 +0800 Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
> If set CONFIG_FUNCTION_TRACER=y, we can use the following command to > disable ftrace after boot up: > echo 0 > /proc/sys/kernel/ftrace_enabled
I'd love to just remove that. It's original purpose was to stop function tracing when the latency tracers were active. That's now done via a tracefs option. The "ftrace_enabled" really has no use anymore.
> > ftrace_disabled is much stronger than ftrace_enabled, introduce a new > cmdline argument ftrace_disabled for user to control whether to disable > ftrace when boot up.
"ftrace_disabled" is triggered when an anomaly is detected, and for the safety of the system, ftrace shuts down. It was never meant to be a user triggered event.
You have no rationale for this change. What's the purpose of this?
-- Steve
> > Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> > --- > kernel/trace/ftrace.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 72ef4dc..a015699 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -5517,6 +5517,14 @@ static char ftrace_filter_buf[FTRACE_FILTER_SIZE] __initdata; > /* Used by function selftest to not test if filter is set */ > bool ftrace_filter_param __initdata; > > +static int __init set_ftrace_disabled(char *str) > +{ > + pr_info("Set ftrace_disabled to disable ftrace\n"); > + ftrace_disabled = 1; > + return 1; > +} > +__setup("ftrace_disabled", set_ftrace_disabled); > + > static int __init set_ftrace_notrace(char *str) > { > ftrace_filter_param = true;
| |