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References: <20180531051641.8473-1-peterx@redhat.com>
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From: Eric Blake <eblake@redhat.com>
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Date: Thu, 31 May 2018 09:06:05 -0500
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Subject: Re: [Qemu-devel] [RFC v2 1/4] docs: mention shared state protect
 for OOB
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To: Peter Xu <peterx@redhat.com>, qemu-devel@nongnu.org
Cc: =?UTF-8?Q?Marc-Andr=c3=a9_Lureau?= <marcandre.lureau@redhat.com>, "Daniel P . Berrange" <berrange@redhat.com>, Christian Borntraeger <borntraeger@de.ibm.com>, Fam Zheng <famz@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Max Reitz <mreitz@redhat.com>, Eric Auger <eric.auger@redhat.com>, John Snow <jsnow@redhat.com>, Markus Armbruster <armbru@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, "Dr . David Alan Gilbert" <dgilbert@redhat.com>

On 05/31/2018 12:16 AM, Peter Xu wrote:
> Out-Of-Band handlers need to protect shared state if there is any.
> Mention it in the document.
> 
> Suggested-by: Markus Armbruster <armbru@redhat.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>   docs/devel/qapi-code-gen.txt | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/docs/devel/qapi-code-gen.txt b/docs/devel/qapi-code-gen.txt
> index b9b6eabd08..aafc15f100 100644
> --- a/docs/devel/qapi-code-gen.txt
> +++ b/docs/devel/qapi-code-gen.txt
> @@ -680,6 +680,9 @@ OOB command handlers must satisfy the following conditions:
>   - It does not invoke system calls that may block,
>   - It does not access guest RAM that may block when userfaultfd is
>     enabled for postcopy live migration.
> +- It needs to protect possilbe shared states, since as long as a

s/possilbe/possible/
s/states/state/

or even 'protect any shared state'

> +  command supports Out-Of-Band it means the handler can be run in
> +  parallel with the same handler running in the other thread.
>   
>   If in doubt, do not implement OOB execution support.
>   
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org