linux-kernel - Re: [PATCH 2/4] tpm: define __wait_for_tpm_stat to specify variable polling sleep time

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Date:   Wed, 6 Sep 2017 18:28:53 +0530
From:   Nayna <nayna@...ux.vnet.ibm.com>
To:     tpmdd-devel@...ts.sourceforge.net
Cc:     peterhuewe@....de, tpmdd@...horst.net,
        jarkko.sakkinen@...ux.intel.com, jgunthorpe@...idianresearch.com,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-ima-devel@...ts.sourceforge.net, patrickc@...ibm.com
Subject: Re: [PATCH 2/4] tpm: define __wait_for_tpm_stat to specify variable
 polling sleep time

Please ignore these one.. My command took patches recursively from 
directory also.

Sorry for this.

Thanks & Regards,
- Nayna

On 09/06/2017 06:26 PM, Nayna Jain wrote:
> The existing wait_for_tpm_stat() checks the chip status before
> sleeping for 5 msec in a polling loop.  For some functions although
> the status isn't ready immediately, the status returns extremely
> quickly. Waiting for 5 msec causes an unnecessary delay. An
> example is the send() call in the tpms_tis driver.
>
> This patch defines __wait_for_tpm_stat(), allowing the caller
> to specify the polling sleep timeout value within the loop.
> The existing wait_for_tpm_stat() becomes a wrapper for this
> function.
>
> Signed-off-by: Nayna Jain <nayna@...ux.vnet.ibm.com>
> ---
>   drivers/char/tpm/tpm-interface.c | 15 ++++++++++++---
>   drivers/char/tpm/tpm.h           |  3 +++
>   drivers/char/tpm/tpm_tis_core.c  | 11 ++++++-----
>   3 files changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 1d6729be4cd6..b23d006243b7 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -1050,8 +1050,9 @@ static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
>   	return false;
>   }
>
> -int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
> -		      wait_queue_head_t *queue, bool check_cancel)
> +int __wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
> +		      unsigned int poll_sleep, wait_queue_head_t *queue,
> +		      bool check_cancel)
>   {
>   	unsigned long stop;
>   	long rc;
> @@ -1085,7 +1086,7 @@ int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
>   		}
>   	} else {
>   		do {
> -			tpm_msleep(TPM_TIMEOUT);
> +			tpm_msleep(poll_sleep);
>   			status = chip->ops->status(chip);
>   			if ((status & mask) == mask)
>   				return 0;
> @@ -1093,6 +1094,14 @@ int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
>   	}
>   	return -ETIME;
>   }
> +EXPORT_SYMBOL_GPL(__wait_for_tpm_stat);
> +
> +int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
> +		      wait_queue_head_t *queue, bool check_cancel)
> +{
> +	return __wait_for_tpm_stat(chip, mask, timeout, TPM_TIMEOUT,
> +			queue, check_cancel);
> +}
>   EXPORT_SYMBOL_GPL(wait_for_tpm_stat);
>
>   #define TPM_ORD_SAVESTATE 152
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index 2d5466a72e40..eb2f8818eded 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -525,6 +525,9 @@ int tpm_do_selftest(struct tpm_chip *chip);
>   unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal);
>   int tpm_pm_suspend(struct device *dev);
>   int tpm_pm_resume(struct device *dev);
> +int __wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
> +		unsigned long timeout, unsigned int poll_sleep,
> +		wait_queue_head_t *queue, bool check_cancel);
>   int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
>   		      wait_queue_head_t *queue, bool check_cancel);
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 6b9bf4c4d434..d1eab29cb447 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -268,8 +268,8 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len)
>   	status = tpm_tis_status(chip);
>   	if ((status & TPM_STS_COMMAND_READY) == 0) {
>   		tpm_tis_ready(chip);
> -		if (wait_for_tpm_stat
> -		    (chip, TPM_STS_COMMAND_READY, chip->timeout_b,
> +		if (__wait_for_tpm_stat
> +		    (chip, TPM_STS_COMMAND_READY, chip->timeout_b, 1,
>   		     &priv->int_queue, false) < 0) {
>   			rc = -ETIME;
>   			goto out_err;
> @@ -303,7 +303,8 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len)
>   		if (ignore_burst_count)
>   			continue;
>
> -		if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
> +		if (__wait_for_tpm_stat(chip, TPM_STS_VALID,
> +					chip->timeout_c, 1,
>   					&priv->int_queue, false) < 0) {
>   			rc = -ETIME;
>   			goto out_err;
> @@ -320,8 +321,8 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len)
>   	if (rc < 0)
>   		goto out_err;
>
> -	if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
> -				&priv->int_queue, false) < 0) {
> +	if (__wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
> +				1, &priv->int_queue, false) < 0) {
>   		rc = -ETIME;
>   		goto out_err;
>   	}
>