linux-kernel - Re: [PATCH v2 1/4] tpm: Implement tpm_chip_find() and tpm_chip

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Date:   Wed, 20 Jun 2018 14:50:04 -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 v2 1/4] tpm: Implement tpm_chip_find() and tpm_chip_put()
 for other subsystems

On Wed, Jun 20, 2018 at 04:42:33PM -0400, Stefan Berger wrote:
> Implement tpm_chip_find() for other subsystems to find a TPM chip and
> get a reference to that chip. Once done with using the chip, the reference
> is released using tpm_chip_put().
> 
> Signed-off-by: Stefan Berger <stefanb@...ux.vnet.ibm.com>
>  drivers/char/tpm/tpm-chip.c | 37 +++++++++++++++++++++++++++++++++++++
>  include/linux/tpm.h         |  9 +++++++++
>  2 files changed, 46 insertions(+)
> 
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index 0a62c19937b6..eaaf41ce73d8 100644
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -81,6 +81,43 @@ void tpm_put_ops(struct tpm_chip *chip)
>  EXPORT_SYMBOL_GPL(tpm_put_ops);
>  
>  /**
> + * tpm_chip_put() - Release a ref to the tpm_chip
> + * @chip: Chip to put
> + */
> +void tpm_chip_put(struct tpm_chip *chip)
> +{
> +	if (chip)
> +		put_device(&chip->dev);

Rarely like to see those if's inside a put function.. Does it actually
help anything?

Jason