tracing/events: Add trace_event boot option
We already have ftrace= boot option, and this adds a similar
boot option for trace events, so allow trace events to be
enabled at boot, for boot debugging purpose.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A4ACE29.3010407@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 53c8fd3..fecac13 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -17,6 +17,8 @@
#include <linux/ctype.h>
#include <linux/delay.h>
+#include <asm/setup.h>
+
#include "trace_output.h"
#define TRACE_SYSTEM "TRACE_SYSTEM"
@@ -1133,6 +1135,18 @@
extern struct ftrace_event_call __start_ftrace_events[];
extern struct ftrace_event_call __stop_ftrace_events[];
+static char bootup_event_buf[COMMAND_LINE_SIZE] __initdata;
+
+static __init int setup_trace_event(char *str)
+{
+ strlcpy(bootup_event_buf, str, COMMAND_LINE_SIZE);
+ ring_buffer_expanded = 1;
+ tracing_selftest_disabled = 1;
+
+ return 1;
+}
+__setup("trace_event=", setup_trace_event);
+
static __init int event_trace_init(void)
{
struct ftrace_event_call *call;
@@ -1140,6 +1154,8 @@
struct dentry *entry;
struct dentry *d_events;
int ret;
+ char *buf = bootup_event_buf;
+ char *token;
d_tracer = tracing_init_dentry();
if (!d_tracer)
@@ -1185,6 +1201,19 @@
&ftrace_event_format_fops);
}
+ while (true) {
+ token = strsep(&buf, ",");
+
+ if (!token)
+ break;
+ if (!*token)
+ continue;
+
+ ret = ftrace_set_clr_event(token, 1);
+ if (ret)
+ pr_warning("Failed to enable trace event: %s\n", token);
+ }
+
ret = register_module_notifier(&trace_module_nb);
if (ret)
pr_warning("Failed to register trace events module notifier\n");
@@ -1392,10 +1421,10 @@
static __init int event_trace_self_tests_init(void)
{
-
- event_trace_self_tests();
-
- event_trace_self_test_with_function();
+ if (!tracing_selftest_disabled) {
+ event_trace_self_tests();
+ event_trace_self_test_with_function();
+ }
return 0;
}