Commit 8258fb4e authored Apr 26, 2022 by Mark-PK Tsai Committed by Greg Kroah-Hartman Jun 14, 2022

tracing: Avoid adding tracer option before update_tracer_options

[ Upstream commit ef9188bcc6ca1d8a2ad83e826b548e6820721061 ]

To prepare for support asynchronous tracer_init_tracefs initcall,
avoid calling create_trace_option_files before __update_tracer_options.
Otherwise, create_trace_option_files will show warning because
some tracers in trace_types list are already in tr->topts.

For example, hwlat_tracer call register_tracer in late_initcall,
and global_trace.dir is already created in tracing_init_dentry,
hwlat_tracer will be put into tr->topts.
Then if the __update_tracer_options is executed after hwlat_tracer
registered, create_trace_option_files find that hwlat_tracer is
already in tr->topts.

Link: https://lkml.kernel.org/r/20220426122407.17042-2-mark-pk.tsai@mediatek.com

Link: https://lore.kernel.org/lkml/20220322133339.GA32582@xsang-OptiPlex-9020/


Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 40f9fde0

kernel/trace/trace.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -5368,12 +5368,18 @@ static void tracing_set_nop(struct trace_array *tr)
		tr->current_trace = &nop_trace;
		}

		static bool tracer_options_updated;

		static void add_tracer_options(struct trace_array tr, struct tracer t)
		{
		/* Only enable if the directory has been created already. */
		if (!tr->dir)
		return;

		/* Only create trace option files after update_tracer_options finish */
		if (!tracer_options_updated)
		return;

		create_trace_option_files(tr, t);
		}

		@@ -7820,6 +7826,7 @@ static void __update_tracer_options(struct trace_array *tr)
		static void update_tracer_options(struct trace_array *tr)
		{
		mutex_lock(&trace_types_lock);
		tracer_options_updated = true;
		__update_tracer_options(tr);
		mutex_unlock(&trace_types_lock);
		}