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

[Ian Jackson <iwj@xxxxxxxxxxxxxx>]

Julien Grall writes ("[PATCH for-4.16] tools/xenstored: Ignore domain we were 
unable to restore"):
> 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.

Release-Acked-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>