Commit c4846480 authored by Steven Rostedt (Google)'s avatar Steven Rostedt (Google)
Browse files

tracing: Add enabling of events to boot instances 

Add the format of:

  trace_instance=foo,sched:sched_switch,irq_handler_entry,initcall

That will create the "foo" instance and enable the sched_switch event
(here were the "sched" system is explicitly specified), the
irq_handler_entry event, and all events under the system initcall.

Link: https://lkml.kernel.org/r/20230207173026.386114535@goodmis.org



Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarRoss Zwisler <zwisler@google.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent cb1f98c5

Documentation/admin-guide/kernel-parameters.txt

+14 −0
Original line number Diff line number Diff line
@@ -6278,6 +6278,20 @@ 


				/sys/kernel/tracing/instances



			Events can be enabled at the time the instance is created

			via:



				trace_instance=<name>,<system1>:<event1>,<system2>:<event2>



			Note, the "<system*>:" portion is optional if the event is

			unique.



				trace_instance=foo,sched:sched_switch,irq_handler_entry,initcall



			will enable the "sched_switch" event (note, the "sched:" is optional, and

			the same thing would happen if it was left off). The irq_handler_entry

			event, and all events under the "initcall" system.



	trace_options=[option-list]

			[FTRACE] Enable or disable tracer options at boot.

			The option-list is a comma delimited list of options

kernel/trace/trace.c

+4 −0
Original line number Diff line number Diff line
@@ -10188,6 +10188,10 @@ __init static void enable_instances(void) 
		}

		/* Allow user space to delete it */

		trace_array_put(tr);



		while ((tok = strsep(&curr_str, ","))) {

			early_enable_events(tr, tok, true);

		}

	}

}

kernel/trace/trace.h

+2 −0
Original line number Diff line number Diff line
@@ -1334,6 +1334,8 @@ DECLARE_PER_CPU(int, trace_buffered_event_cnt); 
void trace_buffered_event_disable(void);

void trace_buffered_event_enable(void);



void early_enable_events(struct trace_array *tr, char *buf, bool disable_first);



static inline void

__trace_event_discard_commit(struct trace_buffer *buffer,

			     struct ring_buffer_event *event)

kernel/trace/trace_events.c

+4 −5
Original line number Diff line number Diff line
@@ -3750,10 +3750,9 @@ static __init int event_trace_memsetup(void) 
	return 0;

}



static __init void

early_enable_events(struct trace_array *tr, bool disable_first)

__init void

early_enable_events(struct trace_array *tr, char *buf, bool disable_first)

{

	char *buf = bootup_event_buf;

	char *token;

	int ret;
@@ -3806,7 +3805,7 @@ static __init int event_trace_enable(void) 
	 */

	__trace_early_add_events(tr);



	early_enable_events(tr, false);

	early_enable_events(tr, bootup_event_buf, false);



	trace_printk_start_comm();
@@ -3834,7 +3833,7 @@ static __init int event_trace_enable_again(void) 
	if (!tr)

		return -ENODEV;



	early_enable_events(tr, true);

	early_enable_events(tr, bootup_event_buf, true);



	return 0;

}