linux-kernel - [PATCH 4.14 075/143] tpm: move the delay_msec increment after sleep in tpm

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Date:   Fri,  2 Nov 2018 19:34:20 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Nayna Jain <nayna@...ux.vnet.ibm.com>,
        Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 075/143] tpm: move the delay_msec increment after sleep in tpm_transmit()

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 92980756979a9c51be0275f395f4e89c42cf199a ]

Commit e2fb992d82c6 ("tpm: add retry logic") introduced a new loop to
handle the TPM2_RC_RETRY error. The loop retries the command after
sleeping for the specified time, which is incremented exponentially in
every iteration.

Unfortunately, the loop doubles the time before sleeping, causing the
initial sleep to be doubled. This patch fixes the initial sleep time.

Fixes: commit e2fb992d82c6 ("tpm: add retry logic")
Signed-off-by: Nayna Jain <nayna@...ux.vnet.ibm.com>
Reviewed-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/char/tpm/tpm-interface.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index a2070ab86c82..89d5915b1a3f 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -611,12 +611,13 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
 		rc = be32_to_cpu(header->return_code);
 		if (rc != TPM2_RC_RETRY)
 			break;
-		delay_msec *= 2;
+
 		if (delay_msec > TPM2_DURATION_LONG) {
 			dev_err(&chip->dev, "TPM is in retry loop\n");
 			break;
 		}
 		tpm_msleep(delay_msec);
+		delay_msec *= 2;
 		memcpy(buf, save, save_size);
 	}
 	return ret;
-- 
2.17.1