selftest/cgroup: Make test_cpuset_prs.sh deal with pre-isolated CPUs

Since isolated CPUs can be reserved at boot time via the "isolcpus"
boot command line option, these pre-isolated CPUs may interfere with
testing done by test_cpuset_prs.sh.

With the previous commit that incorporates those boot time isolated CPUs
into "cpuset.cpus.isolated", we can check for those before testing is
started to make sure that there will be no interference. Otherwise,
this test will be skipped if incorrect test failure can happen.

As "cpuset.cpus.isolated" is now available in a non cgroup_debug kernel,
we don't need to check for its existence anymore.

Signed-off-by: Waiman Long <[e-mail]>
Signed-off-by: Tejun Heo <[e-mail]>

tools/testing/selftests/cgroup/test_cpuset_prs.sh

···
 echo "" > test/cpuset.cpus
 [[ $RESULT -eq 0 ]] && skip_test "Child cgroups are using cpuset!"
 
+#
+# If isolated CPUs have been reserved at boot time (as shown in
+# cpuset.cpus.isolated), these isolated CPUs should be outside of CPUs 0-7
+# that will be used by this script for testing purpose. If not, some of
+# the tests may fail incorrectly. These isolated CPUs will also be removed
+# before being compared with the expected results.
+#
+BOOT_ISOLCPUS=$(cat $CGROUP2/cpuset.cpus.isolated)
+if [[ -n "$BOOT_ISOLCPUS" ]]
+then
+	[[ $(echo $BOOT_ISOLCPUS | sed -e "s/[,-].*//") -le 7 ]] &&
+		skip_test "Pre-isolated CPUs ($BOOT_ISOLCPUS) overlap CPUs to be tested"
+	echo "Pre-isolated CPUs: $BOOT_ISOLCPUS"
+fi
 cleanup()
 {
 	online_cpus
···
 # Note that isolated CPUs from the sched/domains context include offline
 # CPUs as well as CPUs in non-isolated 1-CPU partition. Those CPUs may
 # not be included in the cpuset.cpus.isolated control file which contains
-# only CPUs in isolated partitions.
+# only CPUs in isolated partitions as well as those that are isolated at
+# boot time.
 #
 # $1 - expected isolated cpu list(s) <isolcpus1>{,<isolcpus2>}
 # <isolcpus1> - expected sched/domains value
···
 	fi
 
 	#
-	# Check the debug isolated cpumask, if present
+	# Check cpuset.cpus.isolated cpumask
 	#
-	[[ -f $ISCPUS ]] && {
+	if [[ -z "$BOOT_ISOLCPUS" ]]
+	then
 		ISOLCPUS=$(cat $ISCPUS)
-		[[ "$EXPECT_VAL2" != "$ISOLCPUS" ]] && {
-			# Take a 50ms pause and try again
-			pause 0.05
-			ISOLCPUS=$(cat $ISCPUS)
-		}
-		[[ "$EXPECT_VAL2" != "$ISOLCPUS" ]] && return 1
-		ISOLCPUS=
+	else
+		ISOLCPUS=$(cat $ISCPUS | sed -e "s/,*$BOOT_ISOLCPUS//")
+	fi
+	[[ "$EXPECT_VAL2" != "$ISOLCPUS" ]] && {
+		# Take a 50ms pause and try again
+		pause 0.05
+		ISOLCPUS=$(cat $ISCPUS)
 	}
+	[[ "$EXPECT_VAL2" != "$ISOLCPUS" ]] && return 1
+	ISOLCPUS=
 
 	#
 	# Use the sched domain in debugfs to check isolated CPUs, if available
···
 		fi
 	done
 	[[ "$ISOLCPUS" = *- ]] && ISOLCPUS=${ISOLCPUS}$LASTISOLCPU
+	[[ -n "BOOT_ISOLCPUS" ]] &&
+		ISOLCPUS=$(echo $ISOLCPUS | sed -e "s/,*$BOOT_ISOLCPUS//")
+
 	[[ "$EXPECT_VAL" = "$ISOLCPUS" ]]
 }
 
···
 }
 
 #
-# Check to see if there are unexpected isolated CPUs left
+# Check to see if there are unexpected isolated CPUs left beyond the boot
+# time isolated ones.
 #
 null_isolcpus_check()
 {