selftests/damon: skip test if DAMON is running

Testing the DAMON debugfs files while DAMON is running makes no sense,
as any write to the debugfs files will fail.  This commit makes the test
be skipped in this case.

Link: https://lkml.kernel.org/r/20211201150440.1088-8-sj@kernel.orgSigned-off-by: NSeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

tools/testing/selftests/damon/debugfs_attrs.sh

@@ -44,6 +44,15 @@ test_content() {
 
 source ./_chk_dependency.sh
 
+ksft_skip=4
+
+damon_onoff="$DBGFS/monitor_on"
+if [ $(cat "$damon_onoff") = "on" ]
+then
+	echo "monitoring is on"
+	exit $ksft_skip
+fi
+
 # Test attrs file
 # ===============