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From:   Masami Hiramatsu <mhiramat@kernel.org>
To:     Steven Rostedt <rostedt@goodmis.org>,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Tom Zanussi <tom.zanussi@linux.intel.com>
Cc:     Ingo Molnar <mingo@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Subject: [RFC PATCH 04/11] tracing: kprobes: Register to dynevent earlier stage
Date:   Sat, 22 Jun 2019 01:18:40 +0900
Message-Id: <156113391986.28344.7189845096759612595.stgit@devnote2>
In-Reply-To: <156113387975.28344.16009584175308192243.stgit@devnote2>
References: <156113387975.28344.16009584175308192243.stgit@devnote2>
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Register kprobe event to dynevent in subsys_initcall level.
This will allow kernel to register new kprobe events in
fs_initcall level via trace_run_command.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 kernel/trace/trace_kprobe.c |   19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 3eb03cf880e1..5166a12a9d49 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1547,11 +1547,12 @@ static __init void setup_boot_kprobe_events(void)
 	enable_boot_kprobe_events();
 }
 
-/* Make a tracefs interface for controlling probe points */
-static __init int init_kprobe_trace(void)
+/*
+ * Register dynevent at subsys_initcall. This allows kernel to setup kprobe
+ * events in fs_initcall without tracefs.
+ */
+static __init int init_kprobe_trace_early(void)
 {
-	struct dentry *d_tracer;
-	struct dentry *entry;
 	int ret;
 
 	ret = dyn_event_register(&trace_kprobe_ops);
@@ -1561,6 +1562,16 @@ static __init int init_kprobe_trace(void)
 	if (register_module_notifier(&trace_kprobe_module_nb))
 		return -EINVAL;
 
+	return 0;
+}
+subsys_initcall(init_kprobe_trace_early);
+
+/* Make a tracefs interface for controlling probe points */
+static __init int init_kprobe_trace(void)
+{
+	struct dentry *d_tracer;
+	struct dentry *entry;
+
 	d_tracer = tracing_init_dentry();
 	if (IS_ERR(d_tracer))
 		return 0;