It is Very Rude to clear dmesg in test scripts. That's because the script may be part of a larger test run, and clearing dmesg potentially destroys the output of other tests.
We can avoid using dmesg -c by saving the content of dmesg before the test, and then using diff to compare that to the dmesg afterward, producing a log with just the added lines.
Signed-off-by: Michael Ellerman mpe@ellerman.id.au --- tools/testing/selftests/lkdtm/run.sh | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/tools/testing/selftests/lkdtm/run.sh b/tools/testing/selftests/lkdtm/run.sh index dadf819148a4..0b409e187c7b 100755 --- a/tools/testing/selftests/lkdtm/run.sh +++ b/tools/testing/selftests/lkdtm/run.sh @@ -59,23 +59,25 @@ 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
base-commit: 192ffb7515839b1cc8457e0a8c1e09783de019d3