selftests/run_kselftest.sh: exit with error if tests fail

Parsing KTAP is quite an inconvenience, but most of the time the thing
you really want to know is "did anything fail"?

Let's give the user the his information without them needing
to parse anything.

Because of the use of subshells and namespaces, this needs to be
communicated via a file. Just write arbitrary data into the file and
treat non-empty content as a signal that something failed.

In case any user depends on the current behaviour, such as running this
from a script with `set -e` and parsing the result for failures
afterwards, add a flag they can set to get the old behaviour, namely
--no-error-on-fail.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Brendan Jackman <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/kselftest/runner.sh

···
 	fi
 }
 
+report_failure()
+{
+	echo "not ok $*"
+	echo "$*" >> "$kselftest_failures_file"
+}
+
 run_one()
 {
 	DIR="$1"
···
 	echo "# $TEST_HDR_MSG"
 	if [ ! -e "$TEST" ]; then
 		echo "# Warning: file $TEST is missing!"
-		echo "not ok $test_num $TEST_HDR_MSG"
+		report_failure "$test_num $TEST_HDR_MSG"
 	else
 		if [ -x /usr/bin/stdbuf ]; then
 			stdbuf="/usr/bin/stdbuf --output=L "
···
 				interpreter=$(head -n 1 "$TEST" | cut -c 3-)
 				cmd="$stdbuf $interpreter ./$BASENAME_TEST"
 			else
-				echo "not ok $test_num $TEST_HDR_MSG"
+				report_failure "$test_num $TEST_HDR_MSG"
 				return
 			fi
 		fi
···
 			echo "ok $test_num $TEST_HDR_MSG # SKIP"
 		elif [ $rc -eq $timeout_rc ]; then \
 			echo "#"
-			echo "not ok $test_num $TEST_HDR_MSG # TIMEOUT $kselftest_timeout seconds"
+			report_failure "$test_num $TEST_HDR_MSG # TIMEOUT $kselftest_timeout seconds"
 		else
-			echo "not ok $test_num $TEST_HDR_MSG # exit=$rc"
+			report_failure "$test_num $TEST_HDR_MSG # exit=$rc"
 		fi)
 		cd - >/dev/null
 	fi

tools/testing/selftests/run_kselftest.sh

···
   -c | --collection COLLECTION	Run all tests from COLLECTION
   -l | --list			List the available collection:test entries
   -d | --dry-run		Don't actually run any tests
+  -f | --no-error-on-fail	Don't exit with an error just because tests failed
   -n | --netns			Run each test in namespace
   -h | --help			Show this usage info
   -o | --override-timeout	Number of seconds after which we timeout
···
 TESTS=""
 dryrun=""
 kselftest_override_timeout=""
+ERROR_ON_FAIL=true
 while true; do
 	case "$1" in
 		-s | --summary)
···
 			exit 0 ;;
 		-d | --dry-run)
 			dryrun="echo"
+			shift ;;
+		-f | --no-error-on-fail)
+			ERROR_ON_FAIL=false
 			shift ;;
 		-n | --netns)
 			RUN_IN_NETNS=1
···
 	available="$(echo "$valid" | sed -e 's/ /\n/g')"
 fi
 
+kselftest_failures_file="$(mktemp --tmpdir kselftest-failures-XXXXXX)"
+export kselftest_failures_file
+
 collections=$(echo "$available" | cut -d: -f1 | sort | uniq)
 for collection in $collections ; do
 	[ -w /dev/kmsg ] && echo "kselftest: Running tests in $collection" >> /dev/kmsg
 	tests=$(echo "$available" | grep "^$collection:" | cut -d: -f2)
 	($dryrun cd "$collection" && $dryrun run_many $tests)
 done
+
+failures="$(cat "$kselftest_failures_file")"
+rm "$kselftest_failures_file"
+if "$ERROR_ON_FAIL" && [ "$failures" ]; then
+	exit 1
+fi