linux-kernel - Re: [PATCH 1/6] tpm: Introduce a kref for the tpm

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Message-ID: <20180621165047.GG11859@linux.intel.com>
Date:   Thu, 21 Jun 2018 19:50:47 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Stefan Berger <stefanb@...ux.vnet.ibm.com>
Cc:     Jason Gunthorpe <jgg@...pe.ca>, linux-integrity@...r.kernel.org,
        zohar@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/6] tpm: Introduce a kref for the tpm_chip

On Wed, Jun 20, 2018 at 03:34:36PM -0400, Stefan Berger wrote:
> On 06/20/2018 02:38 PM, Jason Gunthorpe wrote:
> > On Wed, Jun 20, 2018 at 12:19:43PM -0400, Stefan Berger wrote:
> > > Introduce a kref for the tpm_chip that we initialize when the tpm_chip has
> > > been allocated and release before the tpm_chip is to be freed.
> > > 
> > > Signed-off-by: Stefan Berger <stefanb@...ux.vnet.ibm.com>
> > >   drivers/char/tpm/tpm-chip.c | 24 +++++++++++++++++++-----
> > >   drivers/char/tpm/tpm.h      |  1 +
> > >   2 files changed, 20 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> > > index 0a62c19937b6..a933676194a4 100644
> > > +++ b/drivers/char/tpm/tpm-chip.c
> > > @@ -119,8 +119,24 @@ struct tpm_chip *tpm_chip_find_get(struct tpm_chip *chip)
> > >   	return res;
> > >   }
> > > +static void tpm_chip_free(struct kref *kref)
> > > +{
> > > +	struct tpm_chip *chip = container_of(kref, struct tpm_chip, kref);
> > > +
> > > +	kfree(chip->log.bios_event_log);
> > > +	kfree(chip->work_space.context_buf);
> > > +	kfree(chip->work_space.session_buf);
> > > +	kfree(chip);
> > > +}
> > > +
> > > +static void tpm_chip_put(struct tpm_chip *chip)
> > > +{
> > > +	if (chip)
> > > +		kref_put(&chip->kref, tpm_chip_free);
> > > +}
> > > +
> > >   /**
> > > - * tpm_dev_release() - free chip memory and the device number
> > > + * tpm_dev_release() - free the device number and release reference to chip
> > >    * @dev: the character device for the TPM chip
> > >    *
> > >    * This is used as the release function for the character device.
> > > @@ -133,10 +149,7 @@ static void tpm_dev_release(struct device *dev)
> > >   	idr_remove(&dev_nums_idr, chip->dev_num);
> > >   	mutex_unlock(&idr_lock);
> > > -	kfree(chip->log.bios_event_log);
> > > -	kfree(chip->work_space.context_buf);
> > > -	kfree(chip->work_space.session_buf);
> > > -	kfree(chip);
> > > +	tpm_chip_put(chip);
> > >   }
> > >   static void tpm_devs_release(struct device *dev)
> > > @@ -195,6 +208,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
> > >   	mutex_init(&chip->tpm_mutex);
> > >   	init_rwsem(&chip->ops_sem);
> > > +	kref_init(&chip->kref);
> > >   	chip->ops = ops;
> > > diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> > > index 7f2d0f489e9c..098d7dcc04a4 100644
> > > +++ b/drivers/char/tpm/tpm.h
> > > @@ -211,6 +211,7 @@ struct tpm_chip {
> > >   	struct cdev cdev;
> > >   	struct cdev cdevs;
> > > +	struct kref kref;
> > NAK, there is already a kref in struct device, that one must be used.
> 
> Right. Should make it simpler...

I'll review the next version.

/Jarkko