[qemu-s390x] current s390-next crashes with ERROR:cpus.c:1767:qemu_mutex_lock_iothread: assertion failed: (!qemu_mutex_iothread_locked())

[Christian Borntraeger]

Running the QEMU I/O test now results in errors like
ERROR:cpus.c:1767:qemu_mutex_lock_iothread: assertion failed: 
(!qemu_mutex_iothread_locked())
in several cases (e.g. 068)


+**
+ERROR:/home/cborntra/REPOS/qemu/cpus.c:1767:qemu_mutex_lock_iothread: 
assertion failed: (!qemu_mutex_iothread_locked())
+./common.rc: line 51: 48580 Aborted                 (core dumped) ( if [ -n 
"${QEMU_NEED_PID}" ]; then
+    echo $BASHPID > "${QEMU_TEST_DIR}/qemu-${_QEMU_HANDLE}.pid";
+fi; exec "$QEMU_PROG" $QEMU_OPTIONS "$@" )
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) loadvm 0
 (qemu) loadvm 0
-(qemu) quit
 
 === Saving and reloading a VM state to/from a qcow2 image (-object 
iothread,id=iothread0 -set device.hba0.iothread=iothread0) ===
 
@@ -17,8 +21,11 @@
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) savevm 0
 (qemu) quit
+**
+ERROR:/home/cborntra/REPOS/qemu/cpus.c:1767:qemu_mutex_lock_iothread: 
assertion failed: (!qemu_mutex_iothread_locked())
+./common.rc: line 51: 48624 Aborted                 (core dumped) ( if [ -n 
"${QEMU_NEED_PID}" ]; then
+    echo $BASHPID > "${QEMU_TEST_DIR}/qemu-${_QEMU_HANDLE}.pid";
+fi; exec "$QEMU_PROG" $QEMU_OPTIONS "$@" )
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) loadvm 0
-(qemu) loadvm 0
-(qemu) quit
-*** done
+(qemu) loa*** done
Failures: 068
Failed 1 of 1 tests

Bisect points to 

commit 6a29769cb54f69d346fa12f922f35021c386b596
Author: David Hildenbrand <address@hidden>
Date:   Wed Jun 27 15:44:07 2018 +0200

    s390x/tcg: SET CLOCK COMPARATOR can clear CKC interrupt


and reverting that helps.