[libvirt] [PATCH 2/3] qemu: unlock qemu driver and vm before returning from processWatchdogEvent()

[Eric Blake]

On 04/06/2011 01:57 AM, Wen Congyang wrote:
> When the function processWatchdogEvent() failed, we only free wdEvent, but
> forget to unlock qemu driver and vm, free dumpfile.
> 
> ---
>  src/qemu/qemu_driver.c |   28 +++++++++++++++++++---------
>  1 files changed, 19 insertions(+), 9 deletions(-)

I spoke too soon.

> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index dd84f65..628cfe3 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -2400,19 +2400,22 @@ static void processWatchdogEvent(void *data, void *opaque)
>                              wdEvent->vm->def->name,

Oops - this is reading from wdEvent->vm contents...

>                              (unsigned int)time(NULL)) < 0) {
>                  virReportOOMError();
> -                break;
> +                goto cleanup;
>              }
>  
>              qemuDriverLock(driver);
>              virDomainObjLock(wdEvent->vm);

...prior to obtaining the lock.  I think we need to swap that order.

> +    default:
> +        goto cleanup;
>      }
>  
> +endjob:
> +    if (qemuDomainObjEndJob(wdEvent->vm) == 0)
> +        wdEvent->vm = NULL;
> +
> +unlock:
> +    if (wdEvent->vm)
> +        virDomainObjUnlock(wdEvent->vm);
> +    qemuDriverUnlock(driver);
> +
> +cleanup:
>      VIR_FREE(wdEvent);

If you do that, then nothing in the VIR_DOMAIN_WATCHDOG_ACTION_DUMP case
jumps to cleanup, and after patch 3, the default case also unlocks the
vm rather than jumping to cleanup.  I think you need to send a v2 patch
with 2 and 3 squashed into a single fix.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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