Re: [libvirt] [PATCH 2/2] qemu: Avoid deadlock in autodestroy

Since closeCallbacks were turned into virObjectLockable, we can no longer call virQEMUCloseCallbacks APIs from within a registered close callback. --- src/qemu/qemu_conf.c | 19 ++++--------------- src/qemu/qemu_conf.h | 4 ++++ src/qemu/qemu_domain.h | 1 + src/qemu/qemu_process.c | 10 +++++++++- 4 files changed, 18 insertions(+), 16 deletions(-) diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c index edadf36..fc8e152 100644 --- a/src/qemu/qemu_conf.c +++ b/src/qemu/qemu_conf.c @@ -825,8 +825,6 @@ virQEMUCloseCallbacksRunOne(void *payload, { struct virQEMUCloseCallbacksData *data = opaque; qemuDriverCloseDefPtr closeDef = payload; - unsigned char uuid[VIR_UUID_BUFLEN]; - char uuidstr[VIR_UUID_STRING_BUFLEN]; virDomainObjPtr dom; VIR_DEBUG("conn=%p, thisconn=%p, uuid=%s, cb=%p", @@ -835,18 +833,9 @@ virQEMUCloseCallbacksRunOne(void *payload, if (data->conn != closeDef->conn || !closeDef->cb) return; - if (virUUIDParse(name, uuid) < 0) { - VIR_WARN("Failed to parse %s", (const char *)name); - return; - } - /* We need to reformat uuidstr, because closeDef->cb - * might cause the current hash entry to be removed, - * which means 'name' will have been free()d - */ - virUUIDFormat(uuid, uuidstr); - - if (!(dom = virDomainObjListFindByUUID(data->driver->domains, uuid))) { - VIR_DEBUG("No domain object with UUID %s", uuidstr); + if (!(dom = virDomainObjListFindByUUID(data->driver->domains, name))) { + VIR_DEBUG("No domain object with UUID %s", + (const char *) name); return; } @@ -854,7 +843,7 @@ virQEMUCloseCallbacksRunOne(void *payload, if (dom) virObjectUnlock(dom); - virHashRemoveEntry(data->list, uuidstr); + virHashRemoveEntry(data->list, name); } void diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h index 72380dc..b5a3281 100644 --- a/src/qemu/qemu_conf.h +++ b/src/qemu/qemu_conf.h @@ -254,6 +254,10 @@ struct qemuDomainDiskInfo { int io_status; }; +/* + * To avoid a certain deadlock this callback must never call any + * virQEMUCloseCallbacks* API. + */ typedef virDomainObjPtr (*virQEMUCloseCallback)(virQEMUDriverPtr driver, virDomainObjPtr vm, virConnectPtr conn); diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h index 905b099..c9d5f8b 100644 --- a/src/qemu/qemu_domain.h +++ b/src/qemu/qemu_domain.h @@ -137,6 +137,7 @@ struct _qemuDomainObjPrivate { bool gotShutdown; bool beingDestroyed; + bool autoDestroyed; char *pidfile; int nvcpupids; diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index f987618..74406a6 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -4263,7 +4263,8 @@ void qemuProcessStop(virQEMUDriverPtr driver, qemuDomainCleanupRun(driver, vm); /* Stop autodestroy in case guest is restarted */ - qemuProcessAutoDestroyRemove(driver, vm); + if (!priv->autoDestroyed) + qemuProcessAutoDestroyRemove(driver, vm); /* now that we know it's stopped call the hook if present */ if (virHookPresent(VIR_HOOK_DRIVER_QEMU)) { @@ -4647,8 +4648,15 @@ qemuProcessAutoDestroy(virQEMUDriverPtr driver, goto cleanup; VIR_DEBUG("Killing domain"); + + /* We need to prevent qemuProcessStop from removing this function from + * closeCallbacks since that would cause a deadlock. + */ + priv->autoDestroyed = true; qemuProcessStop(driver, dom, VIR_DOMAIN_SHUTOFF_DESTROYED, VIR_QEMU_PROCESS_STOP_MIGRATED); + priv->autoDestroyed = false; + virDomainAuditStop(dom, "destroyed"); event = virDomainEventNewFromObj(dom, VIR_DOMAIN_EVENT_STOPPED,