On 04/06/2011 01:58 AM, Wen Congyang wrote:
> If the domain is not persistent, and qemu quited unexpectedly before
s/quited/quits/
> calling processWatchdogEvent(), vm will be freed and the function
> processWatchdogEvent() will be dangerous.
>
> ---
> src/qemu/qemu_driver.c | 12 ++++++++----
> src/qemu/qemu_process.c | 4 ++++
> 2 files changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 628cfe3..d02891c 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -2436,15 +2436,19 @@ static void processWatchdogEvent(void *data, void *opaque)
> }
> break;
> default:
> - goto cleanup;
> + qemuDriverLock(driver);
> + virDomainObjLock(wdEvent->vm);
> + goto unlock;
> }
>
> 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)
> + if (virDomainObjUnref(wdEvent->vm) > 0)
> virDomainObjUnlock(wdEvent->vm);
> qemuDriverUnlock(driver);
>
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index 48ecd5c..321374c 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));
ACK to the need to do this. Hmm, maybe we should just squash 2 and 3
together into one patch. Also, I found a flaw in 2 while reviewing this
one.
--
Eric Blake eblake@xxxxxxxxxx +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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