Re: [PATCH v2 4/4] tpm: use tpm_msleep() value as max delay

From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Nayna Jain <nayna@linux.vnet.ibm.com>
Cc: tpmdd-devel@lists.sourceforge.net, peterhuewe@gmx.de,
	tpmdd@selhorst.net, jgunthorpe@obsidianresearch.com,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-ima-devel@lists.sourceforge.net, patrickc@us.ibm.com
Subject: Re: [PATCH v2 4/4] tpm: use tpm_msleep() value as max delay
Date: Thu, 14 Sep 2017 05:28:56 -0700	[thread overview]
Message-ID: <20170914122856.guu76zv6xb5kdrfc@linux.intel.com> (raw)
In-Reply-To: <54cc7899-28df-3630-3337-684b561f3760@linux.vnet.ibm.com>

On Thu, Sep 14, 2017 at 02:55:34PM +0530, Nayna Jain wrote:
> 
> 
> On 09/13/2017 06:17 AM, Jarkko Sakkinen wrote:
> > On Wed, Sep 06, 2017 at 08:56:39AM -0400, Nayna Jain wrote:
> > > Currently, tpm_msleep() uses delay_msec as the minimum value in
> > > usleep_range. However, that is the maximum time we want to wait.
> > > The function is modified to use the delay_msec as the maximum
> > > value, not the minimum value.
> > > 
> > > After this change, performance on a TPM 1.2 with an 8 byte
> > > burstcount for 1000 extends improved from ~9sec to ~8sec.
> > > 
> > > Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
> > > Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
> > > ---
> > >   drivers/char/tpm/tpm.h | 4 ++--
> > >   1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> > > index eb2f8818eded..ff5a8b7b80b9 100644
> > > --- a/drivers/char/tpm/tpm.h
> > > +++ b/drivers/char/tpm/tpm.h
> > > @@ -533,8 +533,8 @@ int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
> > >   static inline void tpm_msleep(unsigned int delay_msec)
> > >   {
> > > -	usleep_range(delay_msec * 1000,
> > > -		     (delay_msec * 1000) + TPM_TIMEOUT_RANGE_US);
> > > +	usleep_range((delay_msec * 1000) - TPM_TIMEOUT_RANGE_US,
> > > +		     delay_msec * 1000);
> > >   };
> > >   struct tpm_chip *tpm_chip_find_get(int chip_num);
> > > -- 
> > > 2.13.3
> > > 
> > Doesn't this need a Fixes tag?
> Yeah.. will add.

No need just for that. I'll test this when I'm back in Finland.
It was a question just to check that I'm in the same page  :-)

/Jarkko