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    SubjectRe: [PATCH 00/11] Use copy_process in vhost layer
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    On 3/11/23 11:21 AM, Linus Torvalds wrote:
    > On Fri, Mar 10, 2023 at 2:04 PM Mike Christie
    > <michael.christie@oracle.com> wrote:
    >>
    >> The following patches were made over Linus's tree and apply over next. They
    >> allow the vhost layer to use copy_process instead of using
    >> workqueue_structs to create worker threads for VM's devices.
    >
    > Ok, all these patches looked fine to me from a quick scan - nothing
    > that I reacted to as objectionable, and several of them looked like
    > nice cleanups.
    >
    > The only one I went "Why do you do it that way" for was in 10/11
    > (entirely internal to vhost, so I don't feel too strongly about this)
    > how you made "struct vhost_worker" be a pointer in "struct vhost_dev".
    >
    > It _looks_ to me like it could just have been an embedded structure
    > rather than a separate allocation.
    >
    > IOW, why do
    >
    > vhost_dev->worker
    >
    > instead of doing
    >
    > vhost_dev.worker
    >
    > and just having it all in the same allocation?
    >
    > Not a big deal. Maybe you wanted the 'test if worker pointer is NULL'
    > code to stay around, and basically use that pointer as a flag too. Or
    > maybe there is some other reason you want to keep that separate..
    >

    There were 2 reasons:
    1. Yeah, we needed a flag to indicate that the worker was not setup
    for the cases like where userspace just opens the dev then closes it
    without doing the IOCTL that does vhost_dev_set_owner.

    2. I could have handled #1 by embedding the worker in the vhost_dev
    and then just testing worker.vtsk. However, I have a followup patchset
    that allows us to create multiple worker threads per device. For
    that patchset I then do:

    - if (vhost_dev->worker)

    + if (vhost_dev->workers)

    so I think it just saved me some typing.

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