tools/testing/selftests/sysctl/sysctl.sh: allow graceful use on older kernels

On old kernels older new test knobs implemented on the test_sysctl
module may not be available.  This is expected, and the selftests test
scripts should be able to run without failures on older kernels.

Generalize a solution so that we test for each required test target file
for each test by requiring each test description to annotate their
respective test target file.  If the target file does not exist, we skip
the test gracefully.

Link: http://lkml.kernel.org/r/20190320222831.8243-5-mcgrof@kernel.orgSigned-off-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Eric Sandeen <sandeen@redhat.com>
Cc: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tools/testing/selftests/sysctl/sysctl.sh

@@ -24,19 +24,20 @@ TEST_FILE=$(mktemp)
 
 # This represents
 #
-# TEST_ID:TEST_COUNT:ENABLED
+# TEST_ID:TEST_COUNT:ENABLED:TARGET
 #
 # TEST_ID: is the test id number
 # TEST_COUNT: number of times we should run the test
 # ENABLED: 1 if enabled, 0 otherwise
+# TARGET: test target file required on the test_sysctl module
 #
 # Once these are enabled please leave them as-is. Write your own test,
 # we have tons of space.
-ALL_TESTS="0001:1:1"
-ALL_TESTS="$ALL_TESTS 0002:1:1"
-ALL_TESTS="$ALL_TESTS 0003:1:1"
-ALL_TESTS="$ALL_TESTS 0004:1:1"
-ALL_TESTS="$ALL_TESTS 0005:3:1"
+ALL_TESTS="0001:1:1:int_0001"
+ALL_TESTS="$ALL_TESTS 0002:1:1:string_0001"
+ALL_TESTS="$ALL_TESTS 0003:1:1:int_0002"
+ALL_TESTS="$ALL_TESTS 0004:1:1:uint_0001"
+ALL_TESTS="$ALL_TESTS 0005:3:1:int_0003"
 
 test_modprobe()
 {
@@ -157,9 +158,11 @@ reset_vals()
 
 set_orig()
 {
-	if [ ! -z $TARGET ]; then
+	if [ ! -z $TARGET ] && [ ! -z $ORIG ]; then
+		if [ -f ${TARGET} ]; then
 			echo "${ORIG}" > "${TARGET}"
 		fi
+	fi
 }
 
 set_test()
@@ -600,9 +603,21 @@ run_stringtests()
 	test_rc
 }
 
+target_exists()
+{
+	TARGET="${SYSCTL}/$1"
+	TEST_ID="$2"
+
+	if [ ! -f ${TARGET} ] ; then
+		echo "Target for test $TEST_ID: $TARGET not exist, skipping test ..."
+		return 0
+	fi
+	return 1
+}
+
 sysctl_test_0001()
 {
-	TARGET="${SYSCTL}/int_0001"
+	TARGET="${SYSCTL}/$(get_test_target 0001)"
 	reset_vals
 	ORIG=$(cat "${TARGET}")
 	TEST_STR=$(( $ORIG + 1 ))
@@ -614,7 +629,7 @@ sysctl_test_0001()
 
 sysctl_test_0002()
 {
-	TARGET="${SYSCTL}/string_0001"
+	TARGET="${SYSCTL}/$(get_test_target 0002)"
 	reset_vals
 	ORIG=$(cat "${TARGET}")
 	TEST_STR="Testing sysctl"
@@ -627,7 +642,7 @@ sysctl_test_0002()
 
 sysctl_test_0003()
 {
-	TARGET="${SYSCTL}/int_0002"
+	TARGET="${SYSCTL}/$(get_test_target 0003)"
 	reset_vals
 	ORIG=$(cat "${TARGET}")
 	TEST_STR=$(( $ORIG + 1 ))
@@ -640,7 +655,7 @@ sysctl_test_0003()
 
 sysctl_test_0004()
 {
-	TARGET="${SYSCTL}/uint_0001"
+	TARGET="${SYSCTL}/$(get_test_target 0004)"
 	reset_vals
 	ORIG=$(cat "${TARGET}")
 	TEST_STR=$(( $ORIG + 1 ))
@@ -653,7 +668,7 @@ sysctl_test_0004()
 
 sysctl_test_0005()
 {
-	TARGET="${SYSCTL}/int_0003"
+	TARGET="${SYSCTL}/$(get_test_target 0005)"
 	reset_vals
 	ORIG=$(cat "${TARGET}")
 
@@ -722,25 +737,36 @@ function get_test_count()
 {
 	test_num $1
 	TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$1'}')
-	LAST_TWO=${TEST_DATA#*:*}
-	echo ${LAST_TWO%:*}
+	echo ${TEST_DATA} | awk -F":" '{print $2}'
 }
 
 function get_test_enabled()
 {
 	test_num $1
 	TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$1'}')
-	echo ${TEST_DATA#*:*:}
+	echo ${TEST_DATA} | awk -F":" '{print $3}'
+}
+
+function get_test_target()
+{
+	test_num $1
+	TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$1'}')
+	echo ${TEST_DATA} | awk -F":" '{print $4}'
 }
 
 function run_all_tests()
 {
 	for i in $ALL_TESTS ; do
-		TEST_ID=${i%:*:*}
+		TEST_ID=${i%:*:*:*}
 		ENABLED=$(get_test_enabled $TEST_ID)
 		TEST_COUNT=$(get_test_count $TEST_ID)
+		TEST_TARGET=$(get_test_target $TEST_ID)
+		target_exists $TEST_TARGET $TEST_ID
+		if [ $? -ne 1 ]; then
+			continue
+		fi
 		if [[ $ENABLED -eq "1" ]]; then
-			test_case $TEST_ID $TEST_COUNT
+			test_case $TEST_ID $TEST_COUNT $TEST_TARGET
 		fi
 	done
 }
@@ -773,12 +799,14 @@ function watch_case()
 
 function test_case()
 {
-	NUM_TESTS=$DEFAULT_NUM_TESTS
-	if [ $# -eq 2 ]; then
 	NUM_TESTS=$2
-	fi
 
 	i=0
+
+	if target_exists $3 $1; then
+		continue
+	fi
+
 	while [ $i -lt $NUM_TESTS ]; do
 		test_num $1
 		watch_log $i ${TEST_NAME}_test_$1 noclear
@@ -801,15 +829,15 @@ function parse_args()
 		elif [[ "$1" = "-t" ]]; then
 			shift
 			test_num $1
-			test_case $1 $(get_test_count $1)
+			test_case $1 $(get_test_count $1) $(get_test_target $1)
 		elif [[ "$1" = "-c" ]]; then
 			shift
 			test_num $1
 			test_num $2
-			test_case $1 $2
+			test_case $1 $2 $(get_test_target $1)
 		elif [[ "$1" = "-s" ]]; then
 			shift
-			test_case $1 1
+			test_case $1 1 $(get_test_target $1)
 		elif [[ "$1" = "-l" ]]; then
 			list_tests
 		elif [[ "$1" = "-h" || "$1" = "--help" ]]; then