[PATCH] tracing/kprobes: Fix to skip kprobe-events startup test if kprobe-events is used

[Masami Hiramatsu]

commit b6399cc78934 ("tracing/kprobe: Do not run kprobe boot tests
if kprobe_event is on cmdline") had fixed the same issue with
kprobe-events on kernel cmdline, but boot-time tracing re-introduce
similar issue.

When the boot-time tracing uses kprobe-events with ftrace startup
test, it produced a warning on the kprobe-events startup test
because the testcase doesn't expect any kprobe events exists.

To mitigate the warning, skip the kprobe-events startup test
if any kprobe-event is defined before starting the test.

Fixes: 4d655281eb1b ("tracing/boot Add kprobe event support")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
 kernel/trace/trace_kprobe.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index b911e9f6d9f5..515e139236f2 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -25,7 +25,6 @@
 
 /* Kprobe early definition from command line */
 static char kprobe_boot_events_buf[COMMAND_LINE_SIZE] __initdata;
-static bool kprobe_boot_events_enabled __initdata;
 
 static int __init set_kprobe_boot_events(char *str)
 {
@@ -1887,8 +1886,6 @@ static __init void setup_boot_kprobe_events(void)
 		ret = trace_run_command(cmd, create_or_delete_trace_kprobe);
 		if (ret)
 			pr_warn("Failed to add event(%d): %s\n", ret, cmd);
-		else
-			kprobe_boot_events_enabled = true;
 
 		cmd = p;
 	}
@@ -1959,6 +1956,20 @@ find_trace_probe_file(struct trace_kprobe *tk, struct trace_array *tr)
 	return NULL;
 }
 
+static __init int trace_kprobe_exist(void)
+{
+	struct trace_kprobe *tk;
+	struct dyn_event *pos;
+	int n = 0;
+
+	mutex_lock(&event_mutex);
+	for_each_trace_kprobe(tk, pos) {
+		n++;
+	}
+	mutex_unlock(&event_mutex);
+
+	return n;
+}
 /*
  * Nobody but us can call enable_trace_kprobe/disable_trace_kprobe at this
  * stage, we can do this lockless.
@@ -1973,8 +1984,8 @@ static __init int kprobe_trace_self_tests_init(void)
 	if (tracing_is_disabled())
 		return -ENODEV;
 
-	if (kprobe_boot_events_enabled) {
-		pr_info("Skipping kprobe tests due to kprobe_event on cmdline\n");
+	if (trace_kprobe_exist()) {
+		pr_info("Skipping kprobe tests because kprobe_event is used on boot.\n");
 		return 0;
 	}
 
-- 
2.25.1


-- 
Masami Hiramatsu <mhiramat@xxxxxxxxxx>