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

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Message-ID: <20180622204319.GE19151@ziepe.ca>
Date:   Fri, 22 Jun 2018 14:43:19 -0600
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Stefan Berger <stefanb@...ux.vnet.ibm.com>
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 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..

Jason