1 files changed, 34 insertions, 14 deletions

diff --git a/tools/testing/selftests/lkdtm/run.sh b/tools/testing/selftests/lkdtm/run.sh
index dadf819148a4..95e904959207 100755
--- a/tools/testing/selftests/lkdtm/run.sh
+++ b/tools/testing/selftests/lkdtm/run.sh
@@ -8,6 +8,7 @@
 #
 set -e
 TRIGGER=/sys/kernel/debug/provoke-crash/DIRECT
+CLEAR_ONCE=/sys/kernel/debug/clear_warn_once
 KSELFTEST_SKIP_TEST=4
 
 # Verify we have LKDTM available in the kernel.
@@ -25,13 +26,13 @@ fi
 # Figure out which test to run from our script name.
 test=$(basename $0 .sh)
 # Look up details about the test from master list of LKDTM tests.
-line=$(egrep '^#?'"$test"'\b' tests.txt)
+line=$(grep -E '^#?'"$test"'\b' tests.txt)
 if [ -z "$line" ]; then
 	echo "Skipped: missing test '$test' in tests.txt"
 	exit $KSELFTEST_SKIP_TEST
 fi
 # Check that the test is known to LKDTM.
-if ! egrep -q '^'"$test"'$' "$TRIGGER" ; then
+if ! grep -E -q '^'"$test"'$' "$TRIGGER" ; then
 	echo "Skipped: test '$test' missing in $TRIGGER!"
 	exit $KSELFTEST_SKIP_TEST
 fi
@@ -55,34 +56,53 @@ if echo "$test" | grep -q '^#' ; then
 fi
 
 # If no expected output given, assume an Oops with back trace is success.
+repeat=1
 if [ -z "$expect" ]; then
 	expect="call trace:"
+else
+	if echo "$expect" | grep -q '^repeat:' ; then
+		repeat=$(echo "$expect" | cut -d' ' -f1 | cut -d: -f2)
+		expect=$(echo "$expect" | cut -d' ' -f2-)
+	fi
 fi
 
-# Clear out dmesg for output reporting
-dmesg -c >/dev/null
-
 # Prepare log for report checking
-LOG=$(mktemp --tmpdir -t lkdtm-XXXXXX)
+LOG=$(mktemp --tmpdir -t lkdtm-log-XXXXXX)
+DMESG=$(mktemp --tmpdir -t lkdtm-dmesg-XXXXXX)
 cleanup() {
-	rm -f "$LOG"
+	rm -f "$LOG" "$DMESG"
 }
 trap cleanup EXIT
 
-# Most shells yell about signals and we're expecting the "cat" process
-# to usually be killed by the kernel. So we have to run it in a sub-shell
-# and silence errors.
-($SHELL -c 'cat <(echo '"$test"') >'"$TRIGGER" 2>/dev/null) || true
+# Reset WARN_ONCE counters so we trip it each time this runs.
+if [ -w $CLEAR_ONCE ] ; then
+	echo 1 > $CLEAR_ONCE
+fi
+
+# Save existing dmesg so we can detect new content below
+dmesg > "$DMESG"
+
+# Since the kernel is likely killing the process writing to the trigger
+# file, it must not be the script's shell itself. i.e. we cannot do:
+#     echo "$test" >"$TRIGGER"
+# Instead, use "cat" to take the signal. Since the shell will yell about
+# the signal that killed the subprocess, we must ignore the failure and
+# continue. However we don't silence stderr since there might be other
+# useful details reported there in the case of other unexpected conditions.
+for i in $(seq 1 $repeat); do
+	echo "$test" | cat >"$TRIGGER" || true
+done
 
 # Record and dump the results
-dmesg -c >"$LOG"
+dmesg | comm --nocheck-order -13 "$DMESG" - > "$LOG" || true
+
 cat "$LOG"
 # Check for expected output
-if egrep -qi "$expect" "$LOG" ; then
+if grep -E -qi "$expect" "$LOG" ; then
 	echo "$test: saw '$expect': ok"
 	exit 0
 else
-	if egrep -qi XFAIL: "$LOG" ; then
+	if grep -E -qi XFAIL: "$LOG" ; then
 		echo "$test: saw 'XFAIL': [SKIP]"
 		exit $KSELFTEST_SKIP_TEST
 	else