From: Tom Zanussi <tom.zanussi@linux.intel.com>
Date: Wed, 28 Mar 2018 15:10:53 -0500
Subject: tracing: Fix display of hist trigger expressions containing
 timestamps
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: ad0fa4142dc2cc2ac9ea76ab0bc665a2164644fd
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension

When displaying hist triggers, variable references that have the
timestamp field flag set are erroneously displayed as common_timestamp
rather than the variable reference.  Additionally, timestamp
expressions are displayed in the same way.  Fix this by forcing the
timestamp flag handling to follow variable reference and expression
handling.

Before:

  # cat /sys/kernel/debug/tracing/events/sched/sched_switch/trigger
  hist:keys=next_pid:vals=hitcount:wakeup_lat=common_timestamp.usecs:...

After:

  # cat /sys/kernel/debug/tracing/events/sched/sched_switch/trigger
  hist:keys=next_pid:vals=hitcount:wakeup_lat=common_timestamp.usecs-$ts0.usecs:...

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
 kernel/trace/trace_events_hist.c |   19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1686,8 +1686,6 @@ static const char *hist_field_name(struc
 	else if (field->flags & HIST_FIELD_FL_LOG2 ||
 		 field->flags & HIST_FIELD_FL_ALIAS)
 		field_name = hist_field_name(field->operands[0], ++level);
-	else if (field->flags & HIST_FIELD_FL_TIMESTAMP)
-		field_name = "common_timestamp";
 	else if (field->flags & HIST_FIELD_FL_CPU)
 		field_name = "cpu";
 	else if (field->flags & HIST_FIELD_FL_EXPR ||
@@ -1703,7 +1701,8 @@ static const char *hist_field_name(struc
 			field_name = full_name;
 		} else
 			field_name = field->name;
-	}
+	} else if (field->flags & HIST_FIELD_FL_TIMESTAMP)
+		field_name = "common_timestamp";
 
 	if (field_name == NULL)
 		field_name = "";
@@ -4859,23 +4858,15 @@ static void hist_field_print(struct seq_
 	if (hist_field->var.name)
 		seq_printf(m, "%s=", hist_field->var.name);
 
-	if (hist_field->flags & HIST_FIELD_FL_TIMESTAMP)
-		seq_puts(m, "common_timestamp");
-	else if (hist_field->flags & HIST_FIELD_FL_CPU)
+	if (hist_field->flags & HIST_FIELD_FL_CPU)
 		seq_puts(m, "cpu");
 	else if (field_name) {
 		if (hist_field->flags & HIST_FIELD_FL_VAR_REF ||
 		    hist_field->flags & HIST_FIELD_FL_ALIAS)
 			seq_putc(m, '$');
 		seq_printf(m, "%s", field_name);
-	}
-
-	if (hist_field->flags) {
-		const char *flags_str = get_hist_field_flags(hist_field);
-
-		if (flags_str)
-			seq_printf(m, ".%s", flags_str);
-	}
+	} else if (hist_field->flags & HIST_FIELD_FL_TIMESTAMP)
+		seq_puts(m, "common_timestamp");
 }
 
 static int event_hist_trigger_print(struct seq_file *m,