Re: [Qemu-devel] [RFC PATCH V3 1/4] colo-compare: introduce colo compare initlization

[Jason Wang <jasowang@redhat.com>]

On 04/28/2016 05:04 PM, Zhang Chen wrote:
>
>
> On 04/28/2016 04:17 PM, Jason Wang wrote:
>>
>> On 04/28/2016 03:55 PM, Zhang Chen wrote:
>>>
>>> On 04/28/2016 03:16 PM, Jason Wang wrote:
>>>> On 04/28/2016 02:53 PM, Jason Wang wrote:
>>>>> +static void compare_set_outdev(Object *obj, const char *value,
>>>>> Error **errp)
>>>>>> +{
>>>>>> +    CompareState *s = COLO_COMPARE(obj);
>>>>>> +
>>>>>> +    g_free(s->outdev);
>>>>>> +    s->outdev = g_strdup(value);
>>>>>> +}
>>>>>> +
>>>>>> +/*
>>>>>> + * called from the main thread on the primary
>>>>>> + * to setup colo-compare.
>>>>>> + */
>>>>>> +static void colo_compare_complete(UserCreatable *uc, Error **errp)
>>>>>> +{
>>>>>> +    CompareState *s = COLO_COMPARE(uc);
>>>>>> +
>>>>>> +    if (!s->pri_indev || !s->sec_indev || !s->outdev) {
>>>>>> +        error_setg(errp, "colo compare needs 'primary_in' ,"
>>>>>> +                   "'secondary_in','outdev' property set");
>>>>>> +        return;
>>>>>> +    } else if (!strcmp(s->pri_indev, s->outdev) ||
>>>>>> +               !strcmp(s->sec_indev, s->outdev) ||
>>>>>> +               !strcmp(s->pri_indev, s->sec_indev)) {
>>>>>> +        error_setg(errp, "'indev' and 'outdev' could not be same "
>>>>>> +                   "for compare module");
>>>>>> +        return;
>>>>>> +    }
>>>>>> +
>>>>>> +    s->chr_pri_in = qemu_chr_find(s->pri_indev);
>>>>>> +    if (s->chr_pri_in == NULL) {
>>>>>> +        error_setg(errp, "Primary IN Device '%s' not found",
>>>>>> +                   s->pri_indev);
>>>>>> +        return;
>>>>>> +    }
>>>>>> +
>>>>>> +    s->chr_sec_in = qemu_chr_find(s->sec_indev);
>>>>>> +    if (s->chr_sec_in == NULL) {
>>>>>> +        error_setg(errp, "Secondary IN Device '%s' not found",
>>>>>> +                   s->sec_indev);
>>>>>> +        return;
>>>>>> +    }
>>>>>> +
>>>>>> +    s->chr_out = qemu_chr_find(s->outdev);
>>>>>> +    if (s->chr_out == NULL) {
>>>>>> +        error_setg(errp, "OUT Device '%s' not found", s->outdev);
>>>>>> +        return;
>>>>>> +    }
>>>>>> +
>>>>>> +    qemu_chr_fe_claim_no_fail(s->chr_pri_in);
>>>>>> +    qemu_chr_add_handlers(s->chr_pri_in, compare_chr_can_read,
>>>>>> +                          compare_pri_chr_in, NULL, s);
>>>>>> +
>>>>>> +    qemu_chr_fe_claim_no_fail(s->chr_sec_in);
>>>>>> +    qemu_chr_add_handlers(s->chr_sec_in, compare_chr_can_read,
>>>>>> +                          compare_sec_chr_in, NULL, s);
>>>>>> +
>>>> Btw, what's the reason of handling this in main loop? I thought it
>>>> would
>>>> be better to do this in colo thread? Otherwise, you need lots of extra
>>>> synchronizations?
>>> Do you mean we should start/stop/do checkpoint it by colo-frame?
>> I mean we probably want to handle pri_in and sec_in in colo compare
>> thread. Through this way, there's no need for extra synchronization with
>> main loop.
>
> I get your point, but how to do this.
> Now, we use qemu_chr_add_handlers to do this job.

You probably want to start a new main loop in colo comparing thread.

>
>
> Thanks
> zhangchen