linux-kernel - [PATCH v2 2/4] tpm: define __wait_for_tpm_stat to specify variable polling sleep time

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Message-Id: <20170906125643.5070-3-nayna@linux.vnet.ibm.com>
Date:   Wed,  6 Sep 2017 08:56:37 -0400
From:   Nayna Jain <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,
        Nayna Jain <nayna@...ux.vnet.ibm.com>
Subject: [PATCH v2 2/4] tpm: define __wait_for_tpm_stat to specify variable polling sleep time

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.

After this change, performance on a TPM 1.2 with an 8 byte
burstcount for 1000 extends improved from ~14sec to ~10sec.

Signed-off-by: Nayna Jain <nayna@...ux.vnet.ibm.com>
Acked-by: Mimi Zohar <zohar@...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;
 	}
-- 
2.13.3