Re: [PATCH for-4.16] tools/xenstored: Ignore domain we were unable to restore

[Juergen Gross <jgross@xxxxxxxx>]

On 20.10.21 16:45, Julien Grall wrote:
> From: Julien Grall <jgrall@xxxxxxxxxx>
>
> Commit 939775cfd3 "handle dying domains in live update" was meant to
> handle gracefully dying domain. However, the @releaseDomain watch
> will end up to be sent as soon as we finished to restore Xenstored
> state.
>
> This may be before Xen reports the domain to be dying (such as if
> the guest decided to revoke access to the xenstore page). Consequently
> daemon like xenconsoled will not clean-up the domain and it will be
> left as a zombie.
>
> To avoid the problem, mark the connection as ignored. This also
> requires to tweak conn_can_write() and conn_can_read() to prevent
> dereferencing a NULL pointer (the interface will not mapped).
>
> The check conn->is_ignored was originally added after the callbacks
> because the helpers for a socket connection may close the fd. However,
> ignore_connection() will close a socket connection directly. So it is
> fine to do the re-order.
>
> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Juergen

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