Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH 1/6] tpm: Introduce a kref for the tpm_chip
To:     Jason Gunthorpe <jgg@ziepe.ca>
Cc:     linux-integrity@vger.kernel.org, jarkko.sakkinen@linux.intel.com,
        zohar@linux.vnet.ibm.com, linux-kernel@vger.kernel.org
References: <20180620161948.1464255-1-stefanb@linux.vnet.ibm.com>
 <20180620161948.1464255-2-stefanb@linux.vnet.ibm.com>
 <20180620183854.GC27445@ziepe.ca>
From:   Stefan Berger <stefanb@linux.vnet.ibm.com>
Date:   Wed, 20 Jun 2018 15:34:36 -0400
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.8.0
MIME-Version: 1.0
In-Reply-To: <20180620183854.GC27445@ziepe.ca>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Content-Language: en-MW
Message-Id: <0d37dbe0-d0f4-da13-ffa4-4f00d3542390@linux.vnet.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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@linux.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...


>
> Jason
>