1 files changed, 12 insertions, 10 deletions

diff --git a/tools/testing/selftests/lkdtm/run.sh b/tools/testing/selftests/lkdtm/run.sh
index dadf819148a4..ee64ff8df8f4 100755
--- a/tools/testing/selftests/lkdtm/run.sh
+++ b/tools/testing/selftests/lkdtm/run.sh
@@ -25,13 +25,13 @@ 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 $KSELFTEST_SKIP_TEST
 fi
@@ -59,30 +59,32 @@ if [ -z "$expect" ]; then
 	expect="call trace:"
 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
 
+# Save existing dmesg so we can detect new content below
+dmesg > "$DMESG"
+
 # Most shells yell about signals and we're expecting the "cat" process
 # to usually be killed by the kernel. So we have to run it in a sub-shell
 # and silence errors.
 ($SHELL -c 'cat <(echo '"$test"') >'"$TRIGGER" 2>/dev/null) || true
 
 # Record and dump the results
-dmesg -c >"$LOG"
+dmesg | diff --changed-group-format='%>' --unchanged-group-format='' "$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