@@ -113,6 +113,15 @@ static inline int ksft_get_error_cnt(void) { return ksft_cnt.ksft_error; }
static inline void ksft_print_header(void)
{
+ /*
+ * Force line buffering; If stdout is not connected to a terminal, it
+ * will otherwise default to fully buffered, which can cause output
+ * duplication if there is content in the buffer when fork()ing. If
+ * there is a crash, line buffering also means the most recent output
+ * line will be visible.
+ */
+ setvbuf(stdout, NULL, _IOLBF, 0);
+
if (!(getenv("KSFT_TAP_LEVEL")))
printf("TAP version 13\n");
}
@@ -105,15 +105,18 @@ run_one()
echo "# Warning: file $TEST is missing!"
echo "not ok $test_num $TEST_HDR_MSG"
else
+ if [ -x /usr/bin/stdbuf ]; then
+ stdbuf="/usr/bin/stdbuf --output=L "
+ fi
eval kselftest_cmd_args="\$${kselftest_cmd_args_ref:-}"
- cmd="./$BASENAME_TEST $kselftest_cmd_args"
+ cmd="$stdbuf ./$BASENAME_TEST $kselftest_cmd_args"
if [ ! -x "$TEST" ]; then
echo "# Warning: file $TEST is not executable"
if [ $(head -n 1 "$TEST" | cut -c -2) = "#!" ]
then
interpreter=$(head -n 1 "$TEST" | cut -c 3-)
- cmd="$interpreter ./$BASENAME_TEST"
+ cmd="$stdbuf $interpreter ./$BASENAME_TEST"
else
echo "not ok $test_num $TEST_HDR_MSG"
return
The selftests runner pipes the test program's stdout to tap_prefix. The presence of the pipe means that the test program sets its stdout to be fully buffered (as aposed to line buffered when directly connected to the terminal). The block buffering means that there is often content in the buffer at fork() time, which causes the output to end up duplicated. This was causing problems for mm:cow where test results were duplicated 20-30x. Solve this by using `stdbuf`, when available to force the test program to use line buffered mode. This means previously printf'ed results are flushed out of the program before any fork(). Additionally, explicitly set line buffer mode in ksft_print_header(), which means that all test programs that use the ksft framework will benefit even if stdbuf is not present on the system. Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> --- tools/testing/selftests/kselftest.h | 9 +++++++++ tools/testing/selftests/kselftest/runner.sh | 7 +++++-- 2 files changed, 14 insertions(+), 2 deletions(-)