At 03/30/2011 02:05 PM, Hu Tao Write:
> On Wed, Mar 30, 2011 at 12:34:49PM +0800, Wen Congyang wrote:
>> If the domain is not persistent, and qemu quited unexpectedly before
>> calling processWatchdogEvent(), vm will be freed and the function
>> processWatchdogEvent() will be dangerous.
>>
>> ---
>> src/qemu/qemu_driver.c | 10 ++++++----
>> src/qemu/qemu_process.c | 4 ++++
>> 2 files changed, 10 insertions(+), 4 deletions(-)
>>
>> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
>> index d79d61b..c9c681f 100644
>> --- a/src/qemu/qemu_driver.c
>> +++ b/src/qemu/qemu_driver.c
>> @@ -2443,15 +2443,17 @@ static void processWatchdogEvent(void *data, void *opaque)
>> }
>>
>> endjob:
>> - if (qemuDomainObjEndJob(wdEvent->vm) == 0)
>> - wdEvent->vm = NULL;
>> + /* Safe to ignore value since ref count was incremented in
>> + * qemuProcessHandleWatchdog().
>> + */
>> + ignore_value(qemuDomainObjEndJob(wdEvent->vm));
>>
>> unlock:
>> - if (wdEvent->vm)
>> - virDomainObjUnlock(wdEvent->vm);
>> qemuDriverUnlock(driver);
>>
>> cleanup:
>> + if (virDomainObjUnref(wdEvent->vm) > 0)
>> + virDomainObjUnlock(wdEvent->vm);
>
> These two lines should be protected by qemu driver lock.
We should not unlock domain here as we reached here without locking
domain.
Will update this patch.
>
>> VIR_FREE(wdEvent);
>> }
>>
>> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
>> index e31e1b4..cd8c726 100644
>> --- a/src/qemu/qemu_process.c
>> +++ b/src/qemu/qemu_process.c
>> @@ -426,6 +426,10 @@ qemuProcessHandleWatchdog(qemuMonitorPtr mon ATTRIBUTE_UNUSED,
>> if (VIR_ALLOC(wdEvent) == 0) {
>> wdEvent->action = VIR_DOMAIN_WATCHDOG_ACTION_DUMP;
>> wdEvent->vm = vm;
>> + /* Hold an extra reference because we can't allow 'vm' to be
>> + * deleted before handling watchdog event is finished.
>> + */
>> + virDomainObjRef(vm);
>> ignore_value(virThreadPoolSendJob(driver->workerPool, wdEvent));
>> } else
>> virReportOOMError();
>> --
>> 1.7.1
>
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