Re: [Xen-devel] [PATCH 4/8] xen: add locks with timeouts for keyhandlers

[Jan Beulich <jbeulich@xxxxxxxx>]

On 13.02.2020 13:54, Juergen Gross wrote:
> Most keyhandlers are used to dump hypervisor data to the console and
> they are used mostly for debugging purposes. In those cases it might
> happen that some data structures are locked and thus are blocking the
> handler to access the data.
> 
> In order to be able to still get some information don't use plain
> locking functions in the keyhandlers, but a variant of trylocks with
> a timeout value. This allows to wait for some time and to give up in
> case the lock was not obtained.
> 
> Add the main infrastructure for this feature including a new runtime
> parameter allowing to specify the timeout value in milliseconds.
> 
> Use the new locking scheme in the handlers defined in keyhandler.c.

Personally I think trylock (as already used in some places) is the
way to go. Iirc others disagreed, but also didn't like the approach
taken here. I'm not intending to stand in the way if a majority
approves of this model, but I'm not going to ack these changes
myself.

Jan

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