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

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Message-ID: <20161006112357.GA10533@intel.com>
Date:   Thu, 6 Oct 2016 14:23:57 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Cc:     "Winkler, Tomas" <tomas.winkler@...el.com>,
        "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 Wed, Oct 05, 2016 at 10:27:41AM -0600, Jason Gunthorpe wrote:
> On Wed, Oct 05, 2016 at 01:02:34PM +0300, Jarkko Sakkinen wrote:
> 
> > I'll repeat my question: what worse can happen than returning -EPIPE?  I
> > though the whole rw lock scheme was introduced just for this purpose.
> 
> I thought I explained this, if device_del is moved after ops = null
> then if sysfs looses the race it will oops the kernel. device_del hard
> fences sysfs.

Sorry, I missed that comment somehow. Looking at the code it is like
that.

I think that they should be fenced then for the sake of consistency.
I do not see why sysfs code is privileged not to do fencing while other
peers have to do it.

/Jarkko