Re: [PATCH 1/2 v2] tpm: cmd_ready command can be issued only after granting locality

[Jason Gunthorpe]

On Sun, Jan 28, 2018 at 09:17:53PM +0000, Winkler, Tomas wrote:

> > I think if a driver can fail reliquish then it needs some kind of strategy to
> > recover.

> Maybe some driver can and some not, but if it doesn't succeed it
> should return an error.

But you can't just leave the driver in some inconsistent state..

Every time I've audited something to do with 'add error codes to
destroy/free/release' I find driver design issues..

> > Suggest trying the reliquish again on every next request until success,
> > otherwise fail request locality, potentially permanently.
> 
> This is something I rather prevent because it leaves the HW in kind of undefined state 
> ( and we should probably work on that a bit more later).
> As far as I've debugged the flow now, the driver just fails, and the error goes up 
> user space caller or the internal flow is stopped.

But tranmist_command will be called again - then what does the driver
do? The driver needs an answer for that..

If you don't want to retry then I'd rather see request_locality
permanently fail then adding a return code to release.

Jason