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Re: QMP (without OOB) function running in thread different from the main
From: |
Juan Quintela |
Subject: |
Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll |
Date: |
Fri, 28 Apr 2023 10:38:31 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) |
Kevin Wolf <kwolf@redhat.com> wrote:
>>
>> I am perhaps a bit ingenuous here, but it is there a way to convince
>> qemu that snapshot_save_job_bh *HAS* to run on the main thread?
>
> I believe we're talking about a technicality here. I asked another more
> fundamental question that nobody has answered yet:
>
> Why do you think that it's ok to call bdrv_writev_vmstate() without
> holding the BQL?
I will say this function starts by bdrv_ (i.e. block layer people) and
endes with _vmstate (i.e. migration people).
To be honest, I don't know. That is why I _supposed_ you have an idea.
> Because if we come to the conclusion that it's not ok (which is what I
> think), then it doesn't matter whether we violate the condition in the
> main thread or a vcpu thread. It's wrong in both cases, just the failure
> mode differs - one crashes spectacularly with an assertion failure, the
> other has a race condition. Moving from the assertion failure to a race
> condition is not a proper fix.
Fully agree there. Just that I don't know the answer.
Later, Juan.
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll, (continued)
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll, Paolo Bonzini, 2023/04/20
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll, Fiona Ebner, 2023/04/26
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll, Kevin Wolf, 2023/04/27
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll, Fiona Ebner, 2023/04/27
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll, Juan Quintela, 2023/04/27
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll, Peter Xu, 2023/04/27
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll, Fiona Ebner, 2023/04/28
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll, Fiona Ebner, 2023/04/28
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll, Juan Quintela, 2023/04/28
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll, Kevin Wolf, 2023/04/28
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll,
Juan Quintela <=
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll, Kevin Wolf, 2023/04/28
- Re: QMP (without OOB) function running in thread different from the main thread as part of aio_poll, Juan Quintela, 2023/04/28