linux-kernel - Re: [PATCH v3 2/4] tpm: Implement tpm_chip_find() for other subsystems to find a TPM chip

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Date:   Fri, 22 Jun 2018 16:45:47 -0400
From:   Stefan Berger <stefanb@...ux.vnet.ibm.com>
To:     Jason Gunthorpe <jgg@...pe.ca>
Cc:     linux-integrity@...r.kernel.org, jarkko.sakkinen@...ux.intel.com,
        zohar@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/4] tpm: Implement tpm_chip_find() for other
 subsystems to find a TPM chip

On 06/22/2018 04:43 PM, Jason Gunthorpe wrote:
> On Fri, Jun 22, 2018 at 12:46:11PM -0400, Stefan Berger wrote:
>> Implement tpm_chip_find() for other subsystems to find a TPM chip and
>> get a reference to that chip.
>>
>> Signed-off-by: Stefan Berger <stefanb@...ux.vnet.ibm.com>
>>   drivers/char/tpm/tpm-chip.c | 27 +++++++++++++++++++++++++++
>>   include/linux/tpm.h         |  5 +++++
>>   2 files changed, 32 insertions(+)
>>
>> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
>> index 4e83695af068..2520555b1e17 100644
>> +++ b/drivers/char/tpm/tpm-chip.c
>> @@ -81,6 +81,33 @@ void tpm_put_ops(struct tpm_chip *chip)
>>   EXPORT_SYMBOL_GPL(tpm_put_ops);
>>   
>>   /**
>> + * tpm_chip_find() - find a TPM chip and get a reference to it
>> + */
>> +struct tpm_chip *tpm_chip_find(void)
> I feel like this should be called 'tpm_default_chip()'
>
>> +{
>> +	struct tpm_chip *chip, *res = NULL;
>> +	int chip_num = 0;
>> +	int chip_prev;
>> +
>> +	mutex_lock(&idr_lock);
>> +
>> +	do {
>> +		chip_prev = chip_num;
>> +		chip = idr_get_next(&dev_nums_idr, &chip_num);
>> +		if (chip) {
>> +			get_device(&chip->dev);
>> +			res = chip;
>> +			break;
>> +		}
>> +	} while (chip_prev != chip_num);
>> +
>> +	mutex_unlock(&idr_lock);
> And what was tpm_chip_find_get should just call this function..
And then after that each time tpm_get_ops() ?
>
> Jason
>