linux-kernel - Re: [PATCH] tpm: Add explicit chip->ops locking for sysfs attributes.

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Message-ID: <20171120234536.inncp6ey37ofkd74@linux.intel.com>
Date:   Tue, 21 Nov 2017 01:45:36 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Peter Huewe <peterhuewe@....de>,
        Andrey Pronin <apronin@...omium.org>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tpm: Add explicit chip->ops locking for sysfs attributes.

On Mon, Nov 20, 2017 at 02:45:23PM -0800, Guenter Roeck wrote:
> On Tue, Nov 21, 2017 at 12:13:23AM +0200, Jarkko Sakkinen wrote:
> > On Thu, Nov 16, 2017 at 01:25:01PM -0800, Guenter Roeck wrote:
> > > Add explicit chip->ops locking for all sysfs attributes.
> > > This lets us support those attributes on tpm2 devices.
> > > 
> > > Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> > > ---
> > >  drivers/char/tpm/tpm-chip.c  |   4 --
> > >  drivers/char/tpm/tpm-sysfs.c | 125 ++++++++++++++++++++++++++++++++-----------
> > >  2 files changed, 93 insertions(+), 36 deletions(-)
> > 
> > I think the patch looks ok (with a quick skim) as code change. We need
> > it. It should have been already done. Thanks for doing this.
> > 
> > I don't digest the commit message.
> > 
> > You should just to explain why this change needs to be done in order to
> > support sysfs attributes with TPM 2.0 devices and not speculate how it
> > will be used in future commits.
> > 
> 
> How about the following ?
> 
> "tpm: Enable sysfs support for TPM2 devices
> 
> Access to chip->ops on TPM2 devices requires an explicit lock,
> since the pointer is set to NULL in tpm_class_shutdown().
> Implement that lock for sysfs access functions and enable sysfs
> support for TPM2 devices."
> 
> Thanks,
> Guenter

I can go with that. No need to send a new commit just for this :-)

I'll do some testing and give my final thoughts about the code
change and if everything is good I can change the commit message.
If not, submit the next version with that commit message.

/Jarkko