linux-kernel - [for-next][PATCH 06/15] tracing: Require all trace events to have a TRACE

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Message-ID: <20230731231706.089777331@goodmis.org>
Date:   Mon, 31 Jul 2023 19:16:40 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ajay Kaher <akaher@...are.com>
Subject: [for-next][PATCH 06/15] tracing: Require all trace events to have a TRACE_SYSTEM

From: "Steven Rostedt (Google)" <rostedt@...dmis.org>

The creation of the trace event directory requires that a TRACE_SYSTEM is
defined that the trace event directory is added within the system it was
defined in.

The code handled the case where a TRACE_SYSTEM was not added, and would
then add the event at the events directory. But nothing should be doing
this. This code also prevents the implementation of creating dynamic
dentrys for the eventfs system.

As this path has never been hit on correct code, remove it. If it does get
hit, issues a WARN_ON_ONCE() and return ENODEV.

Link: https://lkml.kernel.org/r/1690568452-46553-2-git-send-email-akaher@vmware.com

Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
Signed-off-by: Ajay Kaher <akaher@...are.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 kernel/trace/trace_events.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 578f1f7d49a6..3ecc41f6acd9 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2420,14 +2420,15 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file)
 
 	/*
 	 * If the trace point header did not define TRACE_SYSTEM
-	 * then the system would be called "TRACE_SYSTEM".
+	 * then the system would be called "TRACE_SYSTEM". This should
+	 * never happen.
 	 */
-	if (strcmp(call->class->system, TRACE_SYSTEM) != 0) {
-		d_events = event_subsystem_dir(tr, call->class->system, file, parent);
-		if (!d_events)
-			return -ENOMEM;
-	} else
-		d_events = parent;
+	if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0))
+		return -ENODEV;
+
+	d_events = event_subsystem_dir(tr, call->class->system, file, parent);
+	if (!d_events)
+		return -ENOMEM;
 
 	name = trace_event_name(call);
 	file->dir = tracefs_create_dir(name, d_events);
-- 
2.40.1