From c97618944439c4d71ec4a492dbdf0c83d47c75a3 Mon Sep 17 00:00:00 2001
From: Patrick Bellasi <patrick.bellasi@arm.com>
Date: Tue, 26 Apr 2016 15:28:16 +0100
Subject: [PATCH] cgroups: fix get attributes for controller noprefix mounted

CGroups controller can be mounted by specifying a "noprefix" option,
in which case attribute names are named as:
   <mountpoint>/<attribute_name>
instead of the (more recent) naming schema using:
   <mountpoint>/<contoller_name>.<attribute_name>

For example, Android uses the old format for backward compatibility
with user-space. Thus, it's possible in general to work on a target
system where some controller are mounted "noprefix" while others not.

This patchset adds a set of updates which allows to use the proper
attributes naming schema based on how the controller has been mounted.

This patch provides a more generic implementation of the get attributes
shutils which is working also for noprefix mounted controllers.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
---
 devlib/bin/scripts/shutils.in | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/devlib/bin/scripts/shutils.in b/devlib/bin/scripts/shutils.in
index f69bce3..ef4d3bd 100755
--- a/devlib/bin/scripts/shutils.in
+++ b/devlib/bin/scripts/shutils.in
@@ -62,12 +62,26 @@ ftrace_get_function_stats() {
 ################################################################################
 
 cgroups_get_attributes() {
-	[[ $# -eq 2 ]] || exit -1
+	test $# -eq 2 || exit -1
 	CGROUP="$1"
 	CONTROLLER="$2"
-	$GREP '' $CGROUP/* | \
-		$GREP "$CONTROLLER\." | \
-		$SED -e "s|$CONTROLLER\.||" -e "s|$CGROUP/||"
+	# Check if controller is mounted with "noprefix" option, which is quite
+	# common on Android for backward compatibility
+	ls $CGROUP/$CONTROLLER\.* 2>&1 >/dev/null
+	if [ $? -eq 0 ]; then
+		# no "noprefix" option, attributes format is:
+		#   mnt_point/controller.attribute_name
+		$GREP '' $CGROUP/* | \
+			$GREP "$CONTROLLER\." | \
+			$SED -e "s|$CONTROLLER\.||" -e "s|$CGROUP/||"
+	else
+		# "noprefix" option, attribute format is:
+		#   mnt_point/attribute_name
+		$GREP '' $(\
+			$FIND $CGROUP -type f -maxdepth 1 |
+			$GREP -v -e ".*tasks" -e ".*cgroup\..*") | \
+		$SED "s|$CGROUP/||"
+	fi
 }
 
 cgroups_run_into() {