[PATCH 4.9 076/240] tracing: Treat recording comm for idle task as a success

[Greg Kroah-Hartman]

From: Joel Fernandes <joelaf@xxxxxxxxxx>

commit eaf260ac04d9b4cf9f458d5c97555bfff2da526e upstream.

Currently we stop recording comm for non-idle tasks when switching from/to idle
task since we treat that as a record failure. Fix that by treat recording of
comm for idle task as a success.

Link: http://lkml.kernel.org/r/20170706230023.17942-1-joelaf@xxxxxxxxxx

Cc: kernel-team@xxxxxxxxxxx
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Reported-by: Michael Sartain <mikesart@xxxxxxxxx>
Signed-off-by: Joel Fernandes <joelaf@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 kernel/trace/trace.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1811,7 +1811,11 @@ static int trace_save_cmdline(struct tas
 {
 	unsigned pid, idx;
 
-	if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
+	/* treat recording of idle task as a success */
+	if (!tsk->pid)
+		return 1;
+
+	if (unlikely(tsk->pid > PID_MAX_DEFAULT))
 		return 0;
 
 	/*