[PATCH v2] test: Wait for output to flush out in enable_pid

eugene.loh
2025-06-28T22:30:57Z

From: Eugene Loh <eugene.loh@oracle.com>

Our luck with this test has been quite good, but it sometimes fails
to show its last lines of output. That is, we send a USR1 to the
trigger processes to set off the final output and we immediately
cat the output files. If there is any delay in handling the signal,
the last output will be missing.

Have the processes terminate themselves when their last output is
flushed; then wait for those processes. Also, skip testing altogether if
there is only a single processor to run the two, hard-spinning processes.

Signed-off-by: Eugene Loh <eugene.loh@oracle.com>
---
test/unittest/usdt/tst.enable_pid.sh | 17 ++++++++++++-----
test/unittest/usdt/tst.enable_pid.x | 8 ++++++++
2 files changed, 20 insertions(+), 5 deletions(-)
create mode 100755 test/unittest/usdt/tst.enable_pid.x

diff --git a/test/unittest/usdt/tst.enable_pid.sh b/test/unittest/usdt/tst.enable_pid.sh
index 7f4f68698..296cfb382 100755
--- a/test/unittest/usdt/tst.enable_pid.sh
+++ b/test/unittest/usdt/tst.enable_pid.sh
@@ -33,6 +33,8 @@ EOF
cat > main.c <<EOF
#include <signal.h>
#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
#include "prov.h"

/* We check if the is-enabled probe is or is not enabled (or unknown). */
@@ -41,7 +43,7 @@ cat > main.c <<EOF
#define ENABLED_UNK 3

/* Start with the previous probe "unknown". */
-int prv = ENABLED_UNK;
+int prv = ENABLED_UNK, nepochs_left = 4;
long long num = 0;

/* Report how many times the previous case was encountered. */
@@ -71,6 +73,9 @@ static void mark_epoch(int sig) {
report();
printf("=== epoch ===\n");
fflush(stdout);
+ nepochs_left--;
+ if (nepochs_left <= 0)
+ exit(0);
}

int
@@ -79,7 +84,7 @@ main(int argc, char **argv)
struct sigaction act;

/* Set USR1 to mark epochs. */
- act.sa_flags = 0;
+ memset(&act, 0, sizeof(act));
act.sa_handler = mark_epoch;
if (sigaction(SIGUSR1, &act, NULL)) {
printf("set handler failed\n");
@@ -172,13 +177,15 @@ for pid in 1 $pid1 $pid2 '*'; do
kill -USR1 $pid2
done

+# Wait for the processes.
+wait $pid1
+wait $pid2
+
+# Dump the output.
echo done
echo "========== out 1"; cat out.1
echo "========== out 2"; cat out.2

echo success

-kill -TERM $pid1
-kill -TERM $pid2
-
exit 0
diff --git a/test/unittest/usdt/tst.enable_pid.x b/test/unittest/usdt/tst.enable_pid.x
new file mode 100755
index 000000000..9506674ee
--- /dev/null
+++ b/test/unittest/usdt/tst.enable_pid.x
@@ -0,0 +1,8 @@
+#!/bin/sh
+
+if [ `grep -c ^processor /proc/cpuinfo` -lt 2 ]; then
+ echo test should have at least two processors
+ exit 2
+fi
+
+exit 0
--
2.43.5