Re: [PATCH 2/2] xen/xenbus: check otherend_id only after it has been initialized

[Juergen Gross <jgross@suse.com>]

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On 03.08.26 05:08, Marek Marczykowski-Górecki wrote:
> When device just got initialized (for example on module load), the
> otherend_id field is initialized only after
> xenbus_read_otherend_details() gets called. If xenstore watch triggers
> xenbus_dev_changed() before that, it might consider still zeroed
> otherend_id field (not matching actual xenstore content) as a sign of
> device state reset. It can happen because xenstore watch are handled in
> another thread (xenwatch), which can run in parallel to the initial
> device probe running at module load. In that case, it would call
> device_unregister(), which would deadlock against device probe from
> module init.
> 
> Fix this by considering dev->otherend_id change only after dev->otherend
> is set (which happen after otherend_id is initialized).
> 
> Fixes: e2dcf9065536 "xen/xenbus: better handle backend crash"
> Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>

Reviewed-by: Juergen Gross <jgross@suse.com>


Juergen

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