From: "Winkler, Tomas" <tomas.winkler@intel.com>
To: "Winkler, Tomas" <tomas.winkler@intel.com>,
        Jason Gunthorpe <jgunthorpe@obsidianresearch.com>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
CC: "tpmdd-devel@lists.sourceforge.net" 
        <tpmdd-devel@lists.sourceforge.net>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] tpm: don't destroy chip device prematurely
Thread-Topic: [PATCH] tpm: don't destroy chip device prematurely
Thread-Index: AQHSHJY7jYiWgZcWb0y7/x76d69Sl6CUwviAgAC3bgCAANJWAIAAChaQ
Date: Mon, 3 Oct 2016 07:38:44 +0000
Message-ID: <5B8DA87D05A7694D9FA63FD143655C1B542F46C1@hasmsx108.ger.corp.intel.com>
References: <1475393971-12715-1-git-send-email-tomas.winkler@intel.com>
        <20161002101755.GA25844@intel.com> <20161002102455.GA27464@intel.com>
        <20161002212126.GA25872@obsidianresearch.com>
 <5B8DA87D05A7694D9FA63FD143655C1B542F466B@hasmsx108.ger.corp.intel.com>
In-Reply-To: <5B8DA87D05A7694D9FA63FD143655C1B542F466B@hasmsx108.ger.corp.intel.com>
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> 
> > On Sun, Oct 02, 2016 at 01:24:55PM +0300, Jarkko Sakkinen wrote:
> > > On Sun, Oct 02, 2016 at 01:17:55PM +0300, Jarkko Sakkinen wrote:
> > > > On Sun, Oct 02, 2016 at 10:39:31AM +0300, Tomas Winkler wrote:
> > > > > In tpm_del_char_device device_del is called prior to
> > > > > tpm2_shutdown where it is still used.
> > > > >
> > > > > Fortunately, so far chip->dev was used only for printouts int
> > > > > tpm2_shutdown flow, hence system didn't crash. But with the
> > > > > introduction of runtime power management it will result in
> > > > > shutting down the parent device while it still in use.
> > > > >
> > > > > Fixes: 20e0152393b41 ("tpm: fix crash in tpm_tis
> > > > > deinitialization")
> > > > > Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
> > > >
> > > > Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > > > Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > >
> > > Applied.
> >
> > This patch is wrong, I though the comments were clear. All entry
> > points to find the device must be deleted before we commit to shutting
> down the device.
> >
> > You need to figure out some other way to solve your problem.
> 
> Please  be more specific regarding flows you think will be wrong  with this
> patch, you must agree that the current code is broken even w/o runtime pm.

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. 

> Thanks
> Tomas
> 
> 
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