commit f98882c254f6f0d475214d22f3b792eca08fe88a
author Todd Broch <tbroch@google.com> Tue Apr 16 21:47:33 2019 -0700
committer chrome-bot <chrome-bot@chromium.org> Thu Apr 18 19:52:05 2019 -0700
tree ef1354c31e6415cefa6cd8ff05f7492548914167
parent 58ccd0c6acc772f855c0f5818a5036959d2655fe

Change /sys/kernel/tracing/tracing_enabled due to deprecation.

crrev.com/c/1549739 deprecated tracing_enabled path.  Lucky for us
there's a redundant sysfs file in tracing_on.  This CL changes
autotest to point to that.

BUG=b:130524214, b:130579812
TEST=power_LoadTest.fast passes on eve.

Change-Id: If5e4307da4b3813b8938f56aa1e3394f4666f43f
Reviewed-on: https://chromium-review.googlesource.com/1571168
Commit-Ready: Todd Broch <tbroch@chromium.org>
Tested-by: Todd Broch <tbroch@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Mengqi Guo <mqg@chromium.org>

client/cros/kernel_trace.py

diff --git a/client/cros/kernel_trace.py b/client/cros/kernel_trace.py
index 564e687..d901e55 100644
--- a/client/cros/kernel_trace.py
+++ b/client/cros/kernel_trace.py
@@ -38,7 +38,7 @@
        - currently only supports trace events.  Add other tracers.
     """
     _TRACE_ROOT = '/sys/kernel/debug/tracing'
-    _TRACE_EN_PATH = os.path.join(_TRACE_ROOT, 'tracing_enabled')
+    _TRACE_ON_PATH = os.path.join(_TRACE_ROOT, 'tracing_on')
 
     def __init__(self, flush=True, events=None, on=True):
         """Constructor for KernelTrace class"""
@@ -65,18 +65,16 @@
 
 
     def _onoff(self, val):
-        """Enable/Disable tracing.
+        """Turn tracing on or off.
 
         Arguments:
             val: integer, 1 for on, 0 for off
 
         Raises:
-            error.TestFail: If unable to enable/disable tracing
-              boolean of tracing on/off status
+            error.TestFail: If unable to turn tracing on or off.
         """
-        utils.write_one_line(self._TRACE_EN_PATH, val)
-        fname = os.path.join(self._TRACE_ROOT, 'tracing_on')
-        result = int(utils.read_one_line(fname).strip())
+        utils.write_one_line(self._TRACE_ON_PATH, val)
+        result = int(utils.read_one_line(self._TRACE_ON_PATH).strip())
         if not result == val:
             raise error.TestFail("Unable to %sable tracing" %
                                  'en' if val == 1 else 'dis')
@@ -98,8 +96,7 @@
         Returns:
             True if tracing enabled and at least one event is enabled.
         """
-        fname = os.path.join(self._TRACE_ROOT, 'tracing_on')
-        result = int(utils.read_one_line(fname).strip())
+        result = int(utils.read_one_line(self._TRACE_ON_PATH).strip())
         if result == 1 and len(self._events) > 0:
             return True
         return False