linux-kernel - Re: [PATCH 2/2] tpm, tpm_tis: reuse code in disable

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Date:   Tue, 23 May 2023 22:07:43 +0300
From:   "Jarkko Sakkinen" <jarkko@...nel.org>
To:     "Lino Sanfilippo" <LinoSanfilippo@....de>, <peterhuewe@....de>,
        <jgg@...pe.ca>
Cc:     <jsnitsel@...hat.com>, <hdegoede@...hat.com>,
        <oe-lkp@...ts.linux.dev>, <lkp@...el.com>,
        <peter.ujfalusi@...ux.intel.com>, <peterz@...radead.org>,
        <linux@...ewoehner.de>, <linux-integrity@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <l.sanfilippo@...bus.com>,
        <lukas@...ner.de>, <p.rosenberger@...bus.com>
Subject: Re: [PATCH 2/2] tpm, tpm_tis: reuse code in disable_interrupts()

On Mon May 22, 2023 at 5:31 PM EEST, Lino Sanfilippo wrote:
> From: Lino Sanfilippo <l.sanfilippo@...bus.com>
>
> Avoid code redundancy by shifting part of the code in disable_interrupts()
> into a subfunction and reusing this function in tpm_tis_handle_irq_storm().
> Make sure that in the subfunction the INT_ENABLE register is written with a
> claimed locality even if the caller did not claim it before.
>
> In the shifted code get rid of the variable "rc" by initializing the
> interrupt mask to zero at variable declaration.
>
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@...bus.com>
> ---
>  drivers/char/tpm/tpm_tis_core.c | 36 ++++++++++++++++-----------------
>  1 file changed, 17 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 458ebf8c2f16..8f4f2cb5520f 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -468,25 +468,32 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
>  	return rc;
>  }
>  
> +static void __tpm_tis_disable_interrupts(struct tpm_chip *chip)
> +{
> +	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> +	u32 intmask = 0;
> +
> +	tpm_tis_read32(priv, TPM_INT_ENABLE(priv->locality), &intmask);
> +	intmask &= ~TPM_GLOBAL_INT_ENABLE;
> +
> +	tpm_tis_request_locality(chip, 0);
> +	tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
> +	tpm_tis_relinquish_locality(chip, 0);
> +
> +	chip->flags &= ~TPM_CHIP_FLAG_IRQ;
> +}
> +
>  static void disable_interrupts(struct tpm_chip *chip)
>  {
>  	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> -	u32 intmask;
> -	int rc;
>  
>  	if (priv->irq == 0)
>  		return;
>  
> -	rc = tpm_tis_read32(priv, TPM_INT_ENABLE(priv->locality), &intmask);
> -	if (rc < 0)
> -		intmask = 0;
> -
> -	intmask &= ~TPM_GLOBAL_INT_ENABLE;
> -	rc = tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
> +	__tpm_tis_disable_interrupts(chip);
>  
>  	devm_free_irq(chip->dev.parent, priv->irq, chip);
>  	priv->irq = 0;
> -	chip->flags &= ~TPM_CHIP_FLAG_IRQ;
>  }
>  
>  /*
> @@ -755,20 +762,11 @@ static bool tpm_tis_req_canceled(struct tpm_chip *chip, u8 status)
>  static void tpm_tis_handle_irq_storm(struct tpm_chip *chip)
>  {
>  	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> -	int intmask = 0;
>  
>  	dev_err(&chip->dev, HW_ERR
>  		"TPM interrupt storm detected, polling instead\n");
>  
> -	tpm_tis_read32(priv, TPM_INT_ENABLE(priv->locality), &intmask);
> -
> -	intmask &= ~TPM_GLOBAL_INT_ENABLE;
> -
> -	tpm_tis_request_locality(chip, 0);
> -	tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
> -	tpm_tis_relinquish_locality(chip, 0);
> -
> -	chip->flags &= ~TPM_CHIP_FLAG_IRQ;
> +	__tpm_tis_disable_interrupts(chip);
>  
>  	/*
>  	 * We must not call devm_free_irq() from within the interrupt handler,
> -- 
> 2.40.1

NAK as invidual change w/o further discussion.

Would need to be seen in context. This does not change kernel for
better.

If you want to wrap, please do it in 1/2 and then we can evaluate
whether it makes sense or not.

BR, Jarkko