linux-kernel - Re: [PATCH] tpm: don't destroy chip device prematurely

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Date:   Sun, 2 Oct 2016 13:17:55 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Tomas Winkler <tomas.winkler@...el.com>
Cc:     tpmdd-devel@...ts.sourceforge.net,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tpm: don't destroy chip device prematurely

On Sun, Oct 02, 2016 at 10:39:31AM +0300, Tomas Winkler wrote:
> In tpm_del_char_device device_del is called
> prior to tpm2_shutdown where it is still used.
> 
> Fortunately, so far chip->dev was used only for printouts
> int tpm2_shutdown flow, hence system didn't crash. But with
> the introduction of runtime power management it will result in
> shutting down the parent device while it still in use.
> 
> Fixes: 20e0152393b41 ("tpm: fix crash in tpm_tis deinitialization")
> Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>

Tested-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>

/Jarkko

> ---
>  drivers/char/tpm/tpm-chip.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index e5950131bd90..b1cb0aae8e66 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -261,7 +261,6 @@ static int tpm_add_char_device(struct tpm_chip *chip)
>  static void tpm_del_char_device(struct tpm_chip *chip)
>  {
>  	cdev_del(&chip->cdev);
> -	device_del(&chip->dev);
>  
>  	/* Make the chip unavailable. */
>  	mutex_lock(&idr_lock);
> @@ -274,6 +273,8 @@ static void tpm_del_char_device(struct tpm_chip *chip)
>  		tpm2_shutdown(chip, TPM2_SU_CLEAR);
>  	chip->ops = NULL;
>  	up_write(&chip->ops_sem);
> +
> +	device_del(&chip->dev);
>  }
>  
>  static int tpm1_chip_register(struct tpm_chip *chip)
> -- 
> 2.7.4
>