Re: [RESEND PATCH V10 06/15] monitor: Update tracking iothread users with holder

[Markus Armbruster <armbru@redhat.com>]

Zhang Chen <zhangckid@gmail.com> writes:

> On Tue, Jul 21, 2026 at 8:33 PM Markus Armbruster <armbru@redhat.com> wrote:
>>
>> Zhang Chen <zhangckid@gmail.com> writes:
>>
>> > Based on monitor QOM path tracking iothread users with holder.
>> > Introduce the AioContext in the Monitor struct to avoid repeated calls to
>> > iothread_get_aio_context() and ensure symmetrical ref/unref during
>> > monitor lifecycle.
>> >
>> > Signed-off-by: Zhang Chen <zhangckid@gmail.com>
>>
>> Why are repeated calls bad?
>>
>> How would symmetry be lost?
>>
>
> OK, will add detailed comments like this in the next version:
>
> Avoid repeated calls: Under the holder tracking model, fetching the
> AioContext increments the IOThread refcount and registers holder metadata.
> Dynamically querying it in helper functions (e.g., suspend, BH scheduling)
> leads to redundant refcount churn.

Right here, we still have

    AioContext *iothread_get_aio_context(IOThread *iothread)
    {
        return iothread->ctx;
    }

and complicating code to avoid additional calls feels dubious.

PATCH 14 changes it to

    AioContext *iothread_get_aio_context(IOThread *iothread,
                                         const IOThreadHolder *holder)
    {
        /* Add IOThreadHolder to the list */
        iothread_ref(iothread, holder);

        return iothread->ctx;
     }

Are you making this change in preparation of PATCH 14?

> Ensure lifecycle symmetry: Storing AioContext in mon->ctx establishes a
> strict 1-to-1 lifecycle pairing: a single iothread_ref_and_get_aio_context()
> in monitor_complete() matched by a single iothread_put_aio_context()
> in monitor_cleanup().
>
> Thanks
> Chen