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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2021-06-17 10:51:02 -0400
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2021-06-17 11:01:15 -0400
commitf38601368f4a0c2a9f859511768dc3957e2e1769 (patch)
tree5297b6bc5a3f9c90c0dab4b48114172be15513b5 /kernel/trace
parent8f0901cda14d3be38cd2196d8cf61cdf3b368e34 (diff)
tracing: Add tp_printk_stop_on_boot option
Add a kernel command line option that disables printing of events to console at late_initcall_sync(). This is useful when needing to see specific events written to console on boot up, but not wanting it when user space starts, as user space may make the console so noisy that the system becomes inoperable. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/trace.c40
1 files changed, 29 insertions, 11 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a0d66a056e59..bbc63ac5b47f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -86,6 +86,7 @@ void __init disable_tracing_selftest(const char *reason)
/* Pipe tracepoints to printk */
struct trace_iterator *tracepoint_print_iter;
int tracepoint_printk;
+static bool tracepoint_printk_stop_on_boot __initdata;
static DEFINE_STATIC_KEY_FALSE(tracepoint_printk_key);
/* For tracers that don't implement custom flags */
@@ -256,6 +257,13 @@ static int __init set_tracepoint_printk(char *str)
}
__setup("tp_printk", set_tracepoint_printk);
+static int __init set_tracepoint_printk_stop(char *str)
+{
+ tracepoint_printk_stop_on_boot = true;
+ return 1;
+}
+__setup("tp_printk_stop_on_boot", set_tracepoint_printk_stop);
+
unsigned long long ns2usecs(u64 nsec)
{
nsec += 500;
@@ -9578,6 +9586,8 @@ static __init int tracer_init_tracefs(void)
return 0;
}
+fs_initcall(tracer_init_tracefs);
+
static int trace_panic_handler(struct notifier_block *this,
unsigned long event, void *unused)
{
@@ -9998,7 +10008,7 @@ void __init trace_init(void)
trace_event_init();
}
-__init static int clear_boot_tracer(void)
+__init static void clear_boot_tracer(void)
{
/*
* The default tracer at boot buffer is an init section.
@@ -10008,26 +10018,21 @@ __init static int clear_boot_tracer(void)
* about to be freed.
*/
if (!default_bootup_tracer)
- return 0;
+ return;
printk(KERN_INFO "ftrace bootup tracer '%s' not registered.\n",
default_bootup_tracer);
default_bootup_tracer = NULL;
-
- return 0;
}
-fs_initcall(tracer_init_tracefs);
-late_initcall_sync(clear_boot_tracer);
-
#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
-__init static int tracing_set_default_clock(void)
+__init static void tracing_set_default_clock(void)
{
/* sched_clock_stable() is determined in late_initcall */
if (!trace_boot_clock && !sched_clock_stable()) {
if (security_locked_down(LOCKDOWN_TRACEFS)) {
pr_warn("Can not set tracing clock due to lockdown\n");
- return -EPERM;
+ return;
}
printk(KERN_WARNING
@@ -10037,8 +10042,21 @@ __init static int tracing_set_default_clock(void)
"on the kernel command line\n");
tracing_set_clock(&global_trace, "global");
}
+}
+#else
+static inline void tracing_set_default_clock(void) { }
+#endif
+__init static int late_trace_init(void)
+{
+ if (tracepoint_printk && tracepoint_printk_stop_on_boot) {
+ static_key_disable(&tracepoint_printk_key.key);
+ tracepoint_printk = 0;
+ }
+
+ tracing_set_default_clock();
+ clear_boot_tracer();
return 0;
}
-late_initcall_sync(tracing_set_default_clock);
-#endif
+
+late_initcall_sync(late_trace_init);