[kvm-unit-tests PATCH 1/3] s390x: Fix unreliable panic-loop tests

[Thomas Huth <thuth@redhat.com>]

From: Thomas Huth <thuth@redhat.com>

In our CI, the s390x panic-loop-extint and panic-loop-pgm tests
are sometimes failing. Having a closer look, this seems to be caused
by ncat sometimes complaining about "Connection reset by peer" on stderr,
likely because QEMU terminated (due to the panic) before ncat could
properly tear down the connection. But having some output on stderr is
interpreted as test failure in qemu_fixup_return_code(), so the test is
marked as failed, even though the panic event occurred as expected.

To fix it, drop the usage of ncat here and simply handle the QMP
input and output via normal fifos instead. This has also the advantage
that we do not need an additional program for these tests anymore
that might not be available in the installation.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 scripts/arch-run.bash | 21 +++++----------------
 1 file changed, 5 insertions(+), 16 deletions(-)

diff --git a/scripts/arch-run.bash b/scripts/arch-run.bash
index c440f216..58e4f93f 100644
--- a/scripts/arch-run.bash
+++ b/scripts/arch-run.bash
@@ -63,14 +63,6 @@ qmp ()
 	echo '{ "execute": "qmp_capabilities" }{ "execute":' "$2" '}' | ncat -U $1
 }
 
-qmp_events ()
-{
-	while ! test -S "$1"; do sleep 0.1; done
-	echo '{ "execute": "qmp_capabilities" }{ "execute": "cont" }' |
-		ncat --no-shutdown -U $1 |
-		jq -c 'select(has("event"))'
-}
-
 filter_quiet_msgs ()
 {
 	grep -v "Now migrate the VM (quiet)" |
@@ -295,26 +287,23 @@ do_migration ()
 
 run_panic ()
 {
-	if ! command -v ncat >/dev/null 2>&1; then
-		echo "${FUNCNAME[0]} needs ncat (netcat)" >&2
-		return 77
-	fi
-
 	if ! command -v jq >/dev/null 2>&1; then
 		echo "${FUNCNAME[0]} needs jq" >&2
 		return 77
 	fi
 
 	trap 'trap - TERM ; kill 0 ; exit 2' INT TERM
-	trap 'rm -f ${qmp}' RETURN EXIT
+	trap 'rm -f ${qmp}.in ${qmp}.out' RETURN EXIT
 
 	qmp=$(mktemp -u -t panic-qmp.XXXXXXXXXX)
+	mkfifo ${qmp}.in ${qmp}.out
 
 	# start VM stopped so we don't miss any events
-	"$@" -chardev socket,id=mon,path=${qmp},server=on,wait=off \
+	"$@" -chardev pipe,id=mon,path=${qmp} \
 		-mon chardev=mon,mode=control -S &
+	echo '{ "execute": "qmp_capabilities" }{ "execute": "cont" }' > ${qmp}.in
 
-	panic_event_count=$(qmp_events ${qmp} | jq -c 'select(.event == "GUEST_PANICKED")' | wc -l)
+	panic_event_count=$(jq -c 'select(.event == "GUEST_PANICKED")' < ${qmp}.out | wc -l)
 	if [ "$panic_event_count" -lt 1 ]; then
 		echo "FAIL: guest did not panic"
 		ret=3
-- 
2.50.1