linux-kernel - RE: [PATCH] tpm: don't destroy chip device prematurely

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Date:   Mon, 3 Oct 2016 17:30:31 +0000
From:   "Winkler, Tomas" <tomas.winkler@...el.com>
To:     Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
CC:     "tpmdd-devel@...ts.sourceforge.net" 
        <tpmdd-devel@...ts.sourceforge.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] tpm: don't destroy chip device prematurely

> 
> On Mon, Oct 03, 2016 at 03:42:25PM +0300, Jarkko Sakkinen wrote:
> 
> > > I've looked to the registration code and it indeed has few more
> > > issues
> 
> ?
> 
> > > Maybe TPM_CHIP_FLAG_REGISTERED can be used for sealing the access to
> > > the device during deregistration, current usage is void.
> 
> This is done via chip->ops = NULL and the rwlock scheme.
I'm not this is the best choice, kind of unusual in the subsystems.  
> 
> > Good catch BTW. This flag has gone quite obsolote.
> 
> I think all the drivers have been updated at this point so we can probably get
> rid of it entirely.

I would actually keep it for the tpm2_shutdown exception, not sure this can be handled by ops  = NULL and rwlock.


Thanks
Tomas

> 
> Jason