From: Steven Rostedt (VMware) rostedt@goodmis.org
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 --- kernel/trace/trace_events.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -1114,7 +1114,8 @@ system_enable_read(struct file *filp, ch 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)