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

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: Ben Hutchings <ben@decadent.org.uk>

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index ecf3e9fb8ee484c09ff7e38c8052994a43e82eb7..1e0729443d93ef8fd775b01edb9e29b6fa82554d 100644 (file)
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1584,8 +1584,13 @@ event_create_dir(struct dentry *parent, struct ftrace_event_file *file)
        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);