[GIT PULL][PATCH] tracing: Don't display trigger file for events that can't be enabled

From: Steven Rostedt
Date: Tue May 03 2016 - 19:24:53 EST


Chunyu Hu noticed that if one writes into the trigger files within the
ftrace subsystem of events that it can cause an oops. This file is only
writable by root, but still is a bug that needs to be fixed.

Please pull the latest trace-fixes-v4.6-rc6 tree, which can be found at:


Tag SHA1: 125fdb6b0df754816c8afcdf7eecb85398253bdd
Head SHA1: 854145e0a8e9a05f7366d240e2f99d9c1ca6d6dd

Chunyu Hu (1):
tracing: Don't display trigger file for events that can't be enabled

kernel/trace/trace_events.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
commit 854145e0a8e9a05f7366d240e2f99d9c1ca6d6dd
Author: Chunyu Hu <chuhu@xxxxxxxxxx>
Date: Tue May 3 19:34:34 2016 +0800

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

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@xxxxxxxxxx

Cc: stable@xxxxxxxxxxxxxxx # 3.14+
Fixes: 85f2b08268c01 ("tracing: Add basic event trigger framework")
Signed-off-by: Chunyu Hu <chuhu@xxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 05ddc0820771..6f965864cc02 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2095,8 +2095,13 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file)
trace_create_file("filter", 0644, file->dir, file,

- 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,