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From:   Masami Hiramatsu <mhiramat@kernel.org>
To:     Steven Rostedt <rostedt@goodmis.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Shuah Khan <skhan@linuxfoundation.org>
Cc:     mhiramat@kernel.org, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, Randy Dunlap <rdunlap@infradead.org>,
        Ingo Molnar <mingo@kernel.org>, linux-kselftest@vger.kernel.org
Subject: [PATCH v3 2/8] tracing/boot: Add per-instance tracing_on option support
Date:   Thu, 10 Sep 2020 17:55:15 +0900
Message-Id: <159972811538.428528.2561315102284268611.stgit@devnote2>
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Add per-instance tracing_on option, which will be useful with
traceon/traceoff event trigger actions. For example, if we
disable tracing_on by default and set traceon and traceoff on
a pair of events, we can trace functions between the pair of
events.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 kernel/trace/trace_boot.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index fa0fc08c6ef8..d52d441a17e8 100644
--- a/kernel/trace/trace_boot.c
+++ b/kernel/trace/trace_boot.c
@@ -40,6 +40,16 @@ trace_boot_set_instance_options(struct trace_array *tr, struct xbc_node *node)
 			pr_err("Failed to set option: %s\n", buf);
 	}
 
+	p = xbc_node_find_value(node, "tracing_on", NULL);
+	if (p && *p != '\0') {
+		if (kstrtoul(p, 10, &v))
+			pr_err("Failed to set tracing on: %s\n", p);
+		if (v)
+			tracer_tracing_on(tr);
+		else
+			tracer_tracing_off(tr);
+	}
+
 	p = xbc_node_find_value(node, "trace_clock", NULL);
 	if (p && *p != '\0') {
 		if (tracing_set_clock(tr, p) < 0)