linux-kernel - Re: [tpmdd-devel] [PATCH 2/2] tpm: add sleep only for retry in i2c_nuvoton_write

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1489416862.28954.156.camel@linux.vnet.ibm.com>
Date:   Mon, 13 Mar 2017 10:54:22 -0400
From:   Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        "linux-4.8" <stable@...r.kernel.org>,
        Nayna Jain <nayna@...ux.vnet.ibm.com>
Subject: Re: [tpmdd-devel] [PATCH 2/2] tpm: add sleep only for retry in
 i2c_nuvoton_write_status()

Hi Jarkko,

On Fri, 2017-03-10 at 13:45 -0500, Nayna Jain wrote:
> Currently, there is an unnecessary 1 msec delay added in
> i2c_nuvoton_write_status() for the successful case. This 
> function is called multiple times during send() and recv(),
> which implies adding multiple extra delays for every TPM
> operation.
> 
> This patch calls usleep_range() only if retry is to be done.
> 
> Signed-off-by: Nayna Jain <nayna@...ux.vnet.ibm.com>
> Cc: stable@...r.kernel.org (linux-4.8)
> Reviewed-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>

Either Reviewed-by/Acked-by is fine. 

Can you pick up this patch and replace the original version of "tpm:
msleep() delays - replace with usleep_range()" with the one Nayna
posted?

Thanks!

Mimi

> ---
>  drivers/char/tpm/tpm_i2c_nuvoton.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_i2c_nuvoton.c b/drivers/char/tpm/tpm_i2c_nuvoton.c
> index 0c98c42..c642877 100644
> --- a/drivers/char/tpm/tpm_i2c_nuvoton.c
> +++ b/drivers/char/tpm/tpm_i2c_nuvoton.c
> @@ -124,8 +124,9 @@ static s32 i2c_nuvoton_write_status(struct i2c_client *client, u8 data)
>  	/* this causes the current command to be aborted */
>  	for (i = 0, status = -1; i < TPM_I2C_RETRY_COUNT && status < 0; i++) {
>  		status = i2c_nuvoton_write_buf(client, TPM_STS, 1, &data);
> -		usleep_range(TPM_I2C_BUS_DELAY, TPM_I2C_BUS_DELAY
> -			     + TPM_I2C_DELAY_RANGE);
> +		if (status < 0)
> +			usleep_range(TPM_I2C_BUS_DELAY, TPM_I2C_BUS_DELAY
> +				     + TPM_I2C_DELAY_RANGE);
>  	}
>  	return status;
>  }