From a05ffdce7155769ea5ac3409e1490fb9116dbaed Mon Sep 17 00:00:00 2001
From: Michael Ellerman <mpe@ellerman.id.au>
Date: Mon, 30 Mar 2015 16:21:40 +1100
Subject: [PATCH] ftracetest: Cope properly with stack tracer not being enabled

If the stack tracer (CONFIG_STACK_TRACER) is disabled, the
fgraph-filter-stack test blows chunks:

  [8] ftrace - function graph filters with stack tracer	[FAIL]
  + reset_tracer
  + echo nop
  ./ftracetest: 19: /home/michael/selftests/ftrace/test.d/ftrace/fgraph-filter-stack.tc:
  	cannot create /proc/sys/kernel/stack_tracer_enabled: Directory nonexistent

Fix it by checking if the proc file exists before echoing to it. With
the patch applied it fails correctly with:

  [8] ftrace - function graph filters with stack tracer	[UNSUPPORTED]

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
---
Reading git-format-patch failed