tracing: Do not count ftrace events in top level enable output

commit 256cfdd6fdf70c6fcf0f7c8ddb0ebd73ce8f3bc9 upstream.

The file /sys/kernel/tracing/events/enable is used to enable all events by
echoing in "1", or disabling all events when echoing in "0". To know if all
events are enabled, disabled, or some are enabled but not all of them,
cating the file should show either "1" (all enabled), "0" (all disabled), or
"X" (some enabled but not all of them). This works the same as the "enable"
files in the individule system directories (like tracing/events/sched/enable).

But when all events are enabled, the top level "enable" file shows "X". The
reason is that its checking the "ftrace" events, which are special events
that only exist for their format files. These include the format for the
function tracer events, that are enabled when the function tracer is
enabled, but not by the "enable" file. The check includes these events,
which will always be disabled, and even though all true events are enabled,
the top level "enable" file will show "X" instead of "1".

To fix this, have the check test the event's flags to see if it has the
"IGNORE_ENABLE" flag set, and if so, not test it.

Cc: stable@vger.kernel.org
Fixes: 553552ce1796c ("tracing: Combine event filter_active and enable into single flags field")
Reported-by: "Yordan Karadzhov (VMware)" <y.karadz@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 5bf072e437c413536e0314ce1ac718c113e69eda..1499b2c2799c730ba291bb06d1ffb869586665f6 100644 (file)
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1105,7 +1105,8 @@ system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
        mutex_lock(&event_mutex);
        list_for_each_entry(file, &tr->events, list) {
                call = file->event_call;
-               if (!trace_event_name(call) || !call->class || !call->class->reg)
+               if ((call->flags & TRACE_EVENT_FL_IGNORE_ENABLE) ||
+                   !trace_event_name(call) || !call->class || !call->class->reg)
                        continue;
 
                if (system && strcmp(call->class->system, system->name) != 0)