linux-kernel - Re: [PATCH v3 3/5] tpm: return error code from tpm_gen

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Date:	Tue, 19 Jul 2016 14:27:41 -0600
From:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:	Peter Huewe <peterhuewe@....de>,
	linux-security-module@...r.kernel.org,
	Stefan Berger <stefanb@...ux.vnet.ibm.com>,
	Marcel Selhorst <tpmdd@...horst.net>,
	"moderated list:TPM DEVICE DRIVER" 
	<tpmdd-devel@...ts.sourceforge.net>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 3/5] tpm: return error code from tpm_gen_interrupt()

On Tue, Jul 19, 2016 at 04:32:47PM +0300, Jarkko Sakkinen wrote:
> Return error code from tpm_gen_interrupt() and fail tpm_tis family of
> drivers on a system error. It doesn't make sense to continue if we
> cannot even reach the TPM.
> 
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
>  drivers/char/tpm/tpm-interface.c | 6 +++---
>  drivers/char/tpm/tpm.h           | 2 +-
>  drivers/char/tpm/tpm_tis_core.c  | 4 +++-
>  3 files changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 88dafcd..35b2722 100644
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -466,16 +466,16 @@ ssize_t tpm_getcap(struct tpm_chip *chip, __be32 subcap_id, cap_t *cap,
>   * Returns 0 on success, < 0 in case of fatal error or a value > 0 representing
>   * a TPM error code.
>   */
> -void tpm_gen_interrupt(struct tpm_chip *chip)
> +int tpm_gen_interrupt(struct tpm_chip *chip)

drivers/char/tpm/st33zp24/st33zp24.c needs to be updated too.

I looked at st33zp24.c and it looks broken, I don't see any logic that
de-asserts TPM_CHIP_FLAG_IRQ if the irq test triggered by
tpm_gen_interrupt, so presumably it should not be calling it at all.

IMHO, DT binding devices should never auto-probe IRQS anyhow, we only
do it on PC because PC is insane...

If we fix st33 then I suggest just moving tpm_gen_interrupt into
tpm_tis - nothing else should really be using it..

Jason