tracing: Restore system filter behavior

Though not all events have field 'prev_pid', it was allowed to do this:

  # echo 'prev_pid == 100' > events/sched/filter

but commit 75b8e98263fdb0bfbdeba60d4db463259f1fe8a2 (tracing/filter: Swap
entire filter of events) broke it without any reason.

Link: http://lkml.kernel.org/r/4EAF46CF.8040408@cn.fujitsu.com
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 96efa67..c3da42d 100644 (file)
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -172,6 +172,7 @@ enum {
        TRACE_EVENT_FL_FILTERED_BIT,
        TRACE_EVENT_FL_RECORDED_CMD_BIT,
        TRACE_EVENT_FL_CAP_ANY_BIT,
+       TRACE_EVENT_FL_NO_SET_FILTER_BIT,
 };
 
 enum {
@@ -179,6 +180,7 @@ enum {
        TRACE_EVENT_FL_FILTERED         = (1 << TRACE_EVENT_FL_FILTERED_BIT),
        TRACE_EVENT_FL_RECORDED_CMD     = (1 << TRACE_EVENT_FL_RECORDED_CMD_BIT),
        TRACE_EVENT_FL_CAP_ANY          = (1 << TRACE_EVENT_FL_CAP_ANY_BIT),
+       TRACE_EVENT_FL_NO_SET_FILTER    = (1 << TRACE_EVENT_FL_NO_SET_FILTER_BIT),
 };
 
 struct ftrace_event_call {

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 816d3d0..86040d9 100644 (file)
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1649,7 +1649,9 @@ static int replace_system_preds(struct event_subsystem *system,
                 */
                err = replace_preds(call, NULL, ps, filter_string, true);
                if (err)
-                       goto fail;
+                       call->flags |= TRACE_EVENT_FL_NO_SET_FILTER;
+               else
+                       call->flags &= ~TRACE_EVENT_FL_NO_SET_FILTER;
        }
 
        list_for_each_entry(call, &ftrace_events, list) {
@@ -1658,6 +1660,9 @@ static int replace_system_preds(struct event_subsystem *system,
                if (strcmp(call->class->system, system->name) != 0)
                        continue;
 
+               if (call->flags & TRACE_EVENT_FL_NO_SET_FILTER)
+                       continue;
+
                filter_item = kzalloc(sizeof(*filter_item), GFP_KERNEL);
                if (!filter_item)
                        goto fail_mem;