Re: [Xen-devel] [PATCH v3 2/3] libxl: move begin phase job handling

[Joao Martins <joao.m.martins@xxxxxxxxxx>]

On 02/02/2016 03:39 PM, Jim Fehlig wrote:
> Joao Martins wrote:
>>
>> On 02/02/2016 01:23 AM, Jim Fehlig wrote:
>>> On 01/20/2016 12:00 PM, Joao Martins wrote:
>>>> . From libxlMigrationBegin to libxlDomainMigrateBegin3Params().
>>>> This is a preparatory patch to be able to begin a job in the
>>>> perform phase.
>>>>
>>>> Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
>>>> ---
>>>>  src/libxl/libxl_driver.c    | 18 +++++++++++++++++-
>>>>  src/libxl/libxl_migration.c | 16 +++-------------
>>>>  2 files changed, 20 insertions(+), 14 deletions(-)
>>>>
>>>> diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
>>>> index d34f843..28220b2 100644
>>>> --- a/src/libxl/libxl_driver.c
>>>> +++ b/src/libxl/libxl_driver.c
>>>> @@ -5187,6 +5187,8 @@ libxlDomainMigrateBegin3Params(virDomainPtr domain,
>>>>  {
>>>>      const char *xmlin = NULL;
>>>>      virDomainObjPtr vm = NULL;
>>>> +    libxlDriverPrivatePtr driver;
>>>> +    char *ret;
>>>>  
>>>>  #ifdef LIBXL_HAVE_NO_SUSPEND_RESUME
>>>>      virReportUnsupportedError();
>>>> @@ -5223,7 +5225,21 @@ libxlDomainMigrateBegin3Params(virDomainPtr domain,
>>>>          return NULL;
>>>>      }
>>>>  
>>>> -    return libxlDomainMigrationBegin(domain->conn, vm, xmlin);
>>>> +    driver = domain->conn->privateData;
>>>> +    if (libxlDomainObjBeginJob(driver, vm, LIBXL_JOB_MODIFY) < 0) {
>>>> +        virObjectUnlock(vm);
>>>> +        return NULL;
>>>> +    }
>>>> +
>>>> +    ret = libxlDomainMigrationBegin(domain->conn, vm, xmlin);
>>>> +
>>>> +    if (!libxlDomainObjEndJob(driver, vm))
>>>> +        vm = NULL;
>>> IIRC the qemu driver handles this a bit differently, and probably more
>>> correctly. On the sender, a job is started during the begin phase and ended 
>>> in
>>> the confirm phase. On the receiver, a job is started in the prepare phase 
>>> and
>>> ended in the finish phase. This prevents modifying the virDomainObj between
>>> phases, e.g. the begin and perform phases on the sender. Is it possible to
>>> change the job handling similarly in the libxl migration phases?
>>>
>> Yeah, IIUC I believe this is the behavior depicted by
>> VIR_MIGRATE_CHANGE_PROTECTION flag in which is set by default if the driver
>> support it. So since we're going this way, we should adversite it too in
>> libxlConnectSupportsFeature() ?
> 
> Yep, sounds good.
> 
>> Btw, the P2P patch keeps the original behavior wrt to jobs, and these two
>> patches meant solely for improving job handling in migration in general. 
>> What do
>> you think in making it a separate patch from this series? (with the changes
>> suggested above)
> 
> Agreed. I'll take another look at the P2P patch and push it (after fixing the
> nits) if there are no further comments. Implementing the CHANGE_PROTECTION
> behavior and improving job handling should be done separately.
> 
Cool, Thanks!

> Regards,
> Jim
> 

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