linux-kernel - RE: [PATCH] tpm: tpm_try_transmit() ignore value of go_to

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Date:   Tue, 16 Oct 2018 06:20:29 +0000
From:   "Winkler, Tomas" <tomas.winkler@...el.com>
To:     Jason Gunthorpe <jgg@...pe.ca>
CC:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Nayna Jain <nayna@...ux.vnet.ibm.com>,
        "Usyskin, Alexander" <alexander.usyskin@...el.com>,
        "Struk, Tadeusz" <tadeusz.struk@...el.com>,
        "linux-integrity@...r.kernel.org" <linux-integrity@...r.kernel.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] tpm: tpm_try_transmit() ignore value of go_to_idle()



> 
> On Mon, Oct 15, 2018 at 02:14:34PM +0300, Tomas Winkler wrote:
> > Ignore the return value of go_to_idle() in tpm_try_transmit().
> > Once it may shadow the return value of actual tpm operation, second
> > the consequent command will fail as well and the error will be caought
> > anyway.
> > Last fix wrong goto, that jumped back instead of forward.
> >
> > Fixes: 627448e85c76 ("tpm: separate cmd_ready/go_idle from
> > runtime_pm")
> > Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
> > drivers/char/tpm/tpm-interface.c | 4 +---
> >  1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/drivers/char/tpm/tpm-interface.c
> > b/drivers/char/tpm/tpm-interface.c
> > index 129f640424b7..f69c711bf74a 100644
> > +++ b/drivers/char/tpm/tpm-interface.c
> > @@ -547,9 +547,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip
> *chip,
> >  		dev_err(&chip->dev, "tpm2_commit_space: error %d\n", rc);
> >
> >  out:
> > -	rc = tpm_go_idle(chip, flags);
> > -	if (rc)
> > -		goto out;
> > +	(void)tpm_go_idle(chip, flags);
> 
> We don't really use this style in the kernel, AFAIK.


Right, there are no many of those; just wanted to emphasize that return value is ignored. I can drop (void).

Thanks
Tomas