Patch "tracing: Don't display trigger file for events that can't be enabled" has been added to the 4.4-stable tree

Patch "tracing: Don't display trigger file for events that can't be enabled" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    tracing: Don't display trigger file for events that can't be enabled

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tracing-don-t-display-trigger-file-for-events-that-can-t-be-enabled.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 854145e0a8e9a05f7366d240e2f99d9c1ca6d6dd Mon Sep 17 00:00:00 2001
From: Chunyu Hu <chuhu@redhat.com>
Date: Tue, 3 May 2016 19:34:34 +0800
Subject: tracing: Don't display trigger file for events that can't be enabled

From: Chunyu Hu <chuhu@redhat.com>

commit 854145e0a8e9a05f7366d240e2f99d9c1ca6d6dd upstream.

Currently register functions for events will be called
through the 'reg' field of event class directly without
any check when seting up triggers.

Triggers for events that don't support register through
debug fs (events under events/ftrace are for trace-cmd to
read event format, and most of them don't have a register
function except events/ftrace/functionx) can't be enabled
at all, and an oops will be hit when setting up trigger
for those events, so just not creating them is an easy way
to avoid the oops.

Link: http://lkml.kernel.org/r/1462275274-3911-1-git-send-email-chuhu@redhat.com

Fixes: 85f2b08268c01 ("tracing: Add basic event trigger framework")
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/trace/trace_events.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2107,8 +2107,13 @@ event_create_dir(struct dentry *parent,
 	trace_create_file("filter", 0644, file->dir, file,
 			  &ftrace_event_filter_fops);
 
-	trace_create_file("trigger", 0644, file->dir, file,
-			  &event_trigger_fops);
+	/*
+	 * Only event directories that can be enabled should have
+	 * triggers.
+	 */
+	if (!(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE))
+		trace_create_file("trigger", 0644, file->dir, file,
+				  &event_trigger_fops);
 
 	trace_create_file("format", 0444, file->dir, call,
 			  &ftrace_event_format_fops);


Patches currently in stable-queue which might be from chuhu@redhat.com are

queue-4.4/tracing-don-t-display-trigger-file-for-events-that-can-t-be-enabled.patch