From c89f712923fbd4d09375596d28f5f8025dfcd1d8 Mon Sep 17 00:00:00 2001
From: Brendan Jackman <brendan.jackman@arm.com>
Date: Fri, 25 Nov 2016 11:56:42 +0000
Subject: [PATCH] cgroups: Raise RuntimeError in freeze if no freezer
 controller

Without this patch, this will result in an error due to trying to call
`.cgroup` on None. Making this a RuntimeError instaed means that a) you
get a more useful error message and b) you can catch the exception
without blanket `except Exception as e`.
---
 devlib/module/cgroups.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/devlib/module/cgroups.py b/devlib/module/cgroups.py
index e4b387c..dd514d9 100644
--- a/devlib/module/cgroups.py
+++ b/devlib/module/cgroups.py
@@ -448,6 +448,8 @@ class CgroupsModule(Module):
 
         # Create Freezer CGroup
         freezer = self.controller('freezer')
+        if freezer is None:
+            raise RuntimeError('freezer cgroup controller not present')
         freezer_cg = freezer.cgroup('/DEVLIB_FREEZER')
         thawed_cg = freezer.cgroup('/')