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Date: Fri, 20 May 2016 10:03:17 +0200
From: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20160520080317.GA4861@noname.redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/3] blockdev-backup: Don't move target
 AioContext if it's attached
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To: Fam Zheng <famz@redhat.com>
Cc: qemu-devel@nongnu.org, Max Reitz <mreitz@redhat.com>, Markus Armbruster <armbru@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, qemu-block@nongnu.org

Am 18.05.2016 um 10:24 hat Fam Zheng geschrieben:
> If the BDS is attached, it will want to stay on the AioContext where its
> BlockBackend is. Don't call bdrv_set_aio_context in this case.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  blockdev.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/blockdev.c b/blockdev.c
> index 1892b8e..eb15593 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -3376,8 +3376,18 @@ void do_blockdev_backup(const char *device, const char *target,
>      }
>      target_bs = blk_bs(target_blk);
>  
> +    if (bdrv_get_aio_context(target_bs) != aio_context) {
> +        if (!target_bs->blk) {

How should this ever happen when we have target_bs = blk_bs(target_blk)
two lines above?

> +            /* The target BDS is not attached, we can safely move it to another
> +             * AioContext. */
> +            bdrv_set_aio_context(target_bs, aio_context);
> +        } else {
> +            error_setg(errp, "Target is attached to a different thread from "
> +                             "source.");
> +            goto out;
> +        }
> +    }

Kevin