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Only add the timer when a callback is registered

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The lifetime of the virDomainEventState object is tied to
the lifetime of the driver, which in stateless drivers is
tied to the lifetime of the virConnectPtr.

If we add & remove a timer when allocating/freeing the
virDomainEventState object, we can get a situation where
the timer still triggers once after virDomainEventState
has been freed. The timeout callback can't keep a ref
on the event state though, since that would be a circular
reference.

The trick is to only register the timer when a callback
is registered with the event state & remove the timer
when the callback is unregistered.

The demo for the bug is to run

  while true ; do date ; ../tools/virsh -q -c test:///default 'shutdown test; undefine test; dominfo test' ; done

prior to this fix, it will frequently hang and / or
crash, or corrupt memory
This commit is contained in:
Daniel P. Berrange 2011-12-14 00:25:58 +00:00
parent 34ad13536e
commit 707781fe12
10 changed files with 72 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

87
src/conf/domain_event.c
View File

@ -632,13 +632,9 @@ virDomainEventTimer(int timer ATTRIBUTE_UNUSED, void *opaque)
/**
* virDomainEventStateNew:
* @requireTimer: If true, return an error if registering the timer fails.
* This is fatal for drivers that sit behind the daemon
* (qemu, lxc), since there should always be a event impl
* registered.
*/
virDomainEventStatePtr
virDomainEventStateNew(bool requireTimer)
virDomainEventStateNew(void)
{
virDomainEventStatePtr state = NULL;
@ -659,23 +655,10 @@ virDomainEventStateNew(bool requireTimer)
goto error;
}
if (!(state->queue = virDomainEventQueueNew())) {
if (!(state->queue = virDomainEventQueueNew()))
goto error;
}
if ((state->timer = virEventAddTimeout(-1,
virDomainEventTimer,
state,
NULL)) < 0) {
if (requireTimer == false) {
VIR_DEBUG("virEventAddTimeout failed: No addTimeoutImpl defined. "
"continuing without events.");
} else {
eventReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("could not initialize domain event timer"));
goto error;
}
}
state->timer = -1;
return state;
@ -1314,7 +1297,6 @@ virDomainEventStateFlush(virDomainEventStatePtr state)
state->queue->count = 0;
state->queue->events = NULL;
virEventUpdateTimeout(state->timer, -1);
virDomainEventStateUnlock(state);
virDomainEventQueueDispatch(&tempQueue,
state->callbacks,
@ -1322,7 +1304,6 @@ virDomainEventStateFlush(virDomainEventStatePtr state)
state);
/* Purge any deleted callbacks */
virDomainEventStateLock(state);
virDomainEventCallbackListPurgeMarked(state->callbacks);
state->isDispatching = false;
@ -1350,10 +1331,32 @@ virDomainEventStateRegister(virConnectPtr conn,
void *opaque,
virFreeCallback freecb)
{
int ret;
int ret = -1;
virDomainEventStateLock(state);
if ((state->callbacks->count == 0) &&
(state->timer == -1) &&
(state->timer = virEventAddTimeout(-1,
virDomainEventTimer,
state,
NULL)) < 0) {
eventReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("could not initialize domain event timer"));
goto cleanup;
}
ret = virDomainEventCallbackListAdd(conn, state->callbacks,
callback, opaque, freecb);
if (ret == -1 &&
state->callbacks->count == 0 &&
state->timer != -1) {
virEventRemoveTimeout(state->timer);
state->timer = -1;
}
cleanup:
virDomainEventStateUnlock(state);
return ret;
}
@ -1384,11 +1387,33 @@ virDomainEventStateRegisterID(virConnectPtr conn,
virFreeCallback freecb,
int *callbackID)
{
int ret;
int ret = -1;
virDomainEventStateLock(state);
if ((state->callbacks->count == 0) &&
(state->timer == -1) &&
(state->timer = virEventAddTimeout(-1,
virDomainEventTimer,
state,
NULL)) < 0) {
eventReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("could not initialize domain event timer"));
goto cleanup;
}
ret = virDomainEventCallbackListAddID(conn, state->callbacks,
dom, eventID, cb, opaque, freecb,
callbackID);
if (ret == -1 &&
state->callbacks->count == 0 &&
state->timer != -1) {
virEventRemoveTimeout(state->timer);
state->timer = -1;
}
cleanup:
virDomainEventStateUnlock(state);
return ret;
}
@ -1418,6 +1443,13 @@ virDomainEventStateDeregister(virConnectPtr conn,
state->callbacks, callback);
else
ret = virDomainEventCallbackListRemove(conn, state->callbacks, callback);
if (state->callbacks->count == 0 &&
state->timer != -1) {
virEventRemoveTimeout(state->timer);
state->timer = -1;
}
virDomainEventStateUnlock(state);
return ret;
}
@ -1448,6 +1480,13 @@ virDomainEventStateDeregisterID(virConnectPtr conn,
else
ret = virDomainEventCallbackListRemoveID(conn,
state->callbacks, callbackID);
if (state->callbacks->count == 0 &&
state->timer != -1) {
virEventRemoveTimeout(state->timer);
state->timer = -1;
}
virDomainEventStateUnlock(state);
return ret;
}

2
src/conf/domain_event.h
View File

@ -119,7 +119,7 @@ void virDomainEventFree(virDomainEventPtr event);
void virDomainEventStateFree(virDomainEventStatePtr state);
virDomainEventStatePtr
virDomainEventStateNew(bool requireTimer);
virDomainEventStateNew(void);
void
virDomainEventStateQueue(virDomainEventStatePtr state,

2
src/libxl/libxl_driver.c
View File

@ -928,7 +928,7 @@ libxlStartup(int privileged) {
}
VIR_FREE(log_file);
libxl_driver->domainEventState = virDomainEventStateNew(true);
libxl_driver->domainEventState = virDomainEventStateNew();
if (!libxl_driver->domainEventState)
goto error;

2
src/lxc/lxc_driver.c
View File

@ -2418,7 +2418,7 @@ static int lxcStartup(int privileged)
if (virDomainObjListInit(&lxc_driver->domains) < 0)
goto cleanup;
lxc_driver->domainEventState = virDomainEventStateNew(true);
lxc_driver->domainEventState = virDomainEventStateNew();
if (!lxc_driver->domainEventState)
goto cleanup;

2
src/qemu/qemu_driver.c
View File

@ -431,7 +431,7 @@ qemudStartup(int privileged) {
goto out_of_memory;
/* Init domain events */
qemu_driver->domainEventState = virDomainEventStateNew(true);
qemu_driver->domainEventState = virDomainEventStateNew();
if (!qemu_driver->domainEventState)
goto error;

2
src/remote/remote_driver.c
View File

@ -726,7 +726,7 @@ doRemoteOpen (virConnectPtr conn,
}
}
if (!(priv->domainEventState = virDomainEventStateNew(false)))
if (!(priv->domainEventState = virDomainEventStateNew()))
goto failed;
/* Successful. */

2
src/test/test_driver.c
View File

@ -1137,7 +1137,7 @@ static virDrvOpenStatus testOpen(virConnectPtr conn,
privconn = conn->privateData;
testDriverLock(privconn);
privconn->domainEventState = virDomainEventStateNew(false);
privconn->domainEventState = virDomainEventStateNew();
if (!privconn->domainEventState) {
testDriverUnlock(privconn);
testClose(conn);

2
src/uml/uml_driver.c
View File

@ -413,7 +413,7 @@ umlStartup(int privileged)
if (virDomainObjListInit(&uml_driver->domains) < 0)
goto error;
uml_driver->domainEventState = virDomainEventStateNew(true);
uml_driver->domainEventState = virDomainEventStateNew();
if (!uml_driver->domainEventState)
goto error;

2
src/vbox/vbox_tmpl.c
View File

@ -1034,7 +1034,7 @@ static virDrvOpenStatus vboxOpen(virConnectPtr conn,
#else /* !(VBOX_API_VERSION == 2002) */
if (!(data->domainEvents = virDomainEventStateNew(true))) {
if (!(data->domainEvents = virDomainEventStateNew())) {
vboxUninitialize(data);
return VIR_DRV_OPEN_ERROR;
}

2
src/xen/xen_driver.c
View File

@ -325,7 +325,7 @@ xenUnifiedOpen (virConnectPtr conn, virConnectAuthPtr auth, unsigned int flags)
return VIR_DRV_OPEN_ERROR;
}
if (!(priv->domainEvents = virDomainEventStateNew(true))) {
if (!(priv->domainEvents = virDomainEventStateNew())) {
virMutexDestroy(&priv->lock);
VIR_FREE(priv);
return VIR_DRV_OPEN_ERROR;