linux-kernel - Re: [PATCH v5 08/10] tpm, tpm_tis: Request threaded interrupt handler

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Date:   Wed, 15 Jun 2022 21:24:43 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     LinoSanfilippo@....de
Cc:     peterhuewe@....de, jgg@...pe.ca, stefanb@...ux.vnet.ibm.com,
        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 v5 08/10] tpm, tpm_tis: Request threaded interrupt handler

On Fri, Jun 10, 2022 at 01:08:44PM +0200, LinoSanfilippo@....de wrote:
> From: Lino Sanfilippo <l.sanfilippo@...bus.com>
> 
> The TIS interrupt handler at least has to read and write the interrupt
> status register. In case of SPI both operations result in a call to
> tpm_tis_spi_transfer() which uses the bus_lock_mutex of the spi device
> and thus must only be called from a sleepable context.
> 
> To ensure this request a threaded interrupt handler.
> 
> Fixes: 1a339b658d9d ("tpm_tis_spi: Pass the SPI IRQ down to the driver")
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@...bus.com>
> ---
>  drivers/char/tpm/tpm_tis_core.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 0ef74979bc2c..8b5aa4fdbe92 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -794,8 +794,11 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip, u32 intmask,
>  	int rc;
>  	u32 int_status;
>  
> -	if (devm_request_irq(chip->dev.parent, irq, tis_int_handler, flags,
> -			     dev_name(&chip->dev), chip) != 0) {
> +
> +	rc = devm_request_threaded_irq(chip->dev.parent, irq, NULL,
> +				       tis_int_handler, IRQF_ONESHOT | flags,
> +				       dev_name(&chip->dev), chip);
> +	if (rc) {
>  		dev_info(&chip->dev, "Unable to request irq: %d for probe\n",
>  			 irq);
>  		return -1;
> -- 
> 2.36.1
> 

I actually would not add fixes tag to this because given that
interrupt support is quite unusable, this should not cause any
harm.

The code change itself is fine.

BR, Jarkko