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Re: [PATCH 2/3] Mini-OS: don't crash if no shutdown node is available


  • To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, minios-devel@xxxxxxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx
  • From: Juergen Gross <jgross@xxxxxxxx>
  • Date: Wed, 1 Nov 2023 17:42:04 +0100
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  • Cc: samuel.thibault@xxxxxxxxxxxx, wl@xxxxxxx
  • Delivery-date: Wed, 01 Nov 2023 16:42:09 +0000
  • List-id: Mini-os development list <minios-devel.lists.xenproject.org>

On 01.11.23 17:38, Andrew Cooper wrote:
On 01/11/2023 9:00 am, Juergen Gross wrote:
It might be perfectly fine not to have a control/shutdown Xenstore
node. If this is the case, don't crash, but just terminate the
shutdown thread after issuing a message that shutdown isn't available.

In fini_shutdown() clearing the watch can result in an error now, in
case the early exit above was taken. Just ignore this error now.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Which cases might we not have a control/shutdown node?

Xenstore-stubdom. It should _never_ shutdown, and it isn't really under
control of Xen tools (other than being created).

I'm all for coping better with its absence, but it's not a piece of the
Xen ABI which is optional.

I'd like to differ here. See reasoning above.

And on that front, not crashing is good, but why remove the watch?  What
if it comes into existence later?  Is there any problem with just
leaving the watch outstanding?

A needless waste of memory in Xenstore-stubdom.


Juergen

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