Commit 937fbf11 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt (Google)
Browse files

tracing: Add traceoff_after_boot option 

Sometimes tracing is used to debug issues during the boot process. Since
the trace buffer has a limited amount of storage, it may be prudent to
disable tracing after the boot is finished, otherwise the critical
information may be overwritten.  With this option, the main tracing buffer
will be turned off at the end of the boot process.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lore.kernel.org/20250208103017.48a7ec83@batman.local.home


Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent d082ecbc

Documentation/admin-guide/kernel-parameters.txt

+9 −0
Original line number Diff line number Diff line
@@ -7279,6 +7279,15 @@ 
			See also "Event triggers" in Documentation/trace/events.rst





	traceoff_after_boot

			[FTRACE] Sometimes tracing is used to debug issues

			during the boot process. Since the trace buffer has a

			limited amount of storage, it may be prudent to

			disable tracing after the boot is finished, otherwise

			the critical information may be overwritten.  With this

			option, the main tracing buffer will be turned off at

			the end of the boot process.



	traceoff_on_warning

			[FTRACE] enable this option to disable tracing when a

			warning is hit. This turns off "tracing_on". Tracing can

kernel/trace/trace.c

+11 −0
Original line number Diff line number Diff line
@@ -87,6 +87,7 @@ void __init disable_tracing_selftest(const char *reason) 
static struct trace_iterator *tracepoint_print_iter;

int tracepoint_printk;

static bool tracepoint_printk_stop_on_boot __initdata;

static bool traceoff_after_boot __initdata;

static DEFINE_STATIC_KEY_FALSE(tracepoint_printk_key);



/* For tracers that don't implement custom flags */
@@ -330,6 +331,13 @@ static int __init set_tracepoint_printk_stop(char *str) 
}

__setup("tp_printk_stop_on_boot", set_tracepoint_printk_stop);



static int __init set_traceoff_after_boot(char *str)

{

	traceoff_after_boot = true;

	return 1;

}

__setup("traceoff_after_boot", set_traceoff_after_boot);



unsigned long long ns2usecs(u64 nsec)

{

	nsec += 500;
@@ -10704,6 +10712,9 @@ __init static int late_trace_init(void) 
		tracepoint_printk = 0;

	}



	if (traceoff_after_boot)

		tracing_off();



	tracing_set_default_clock();

	clear_boot_tracer();

	return 0;