linux-kernel - [PATCH v8 07/11] tpm, tpm_tis: do not check for the active locality in interrupt handler

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Message-Id: <20221017235732.10145-8-LinoSanfilippo@gmx.de>
Date:   Tue, 18 Oct 2022 01:57:28 +0200
From:   Lino Sanfilippo <LinoSanfilippo@....de>
To:     peterhuewe@....de, jarkko@...nel.org, jgg@...pe.ca
Cc:     stefanb@...ux.vnet.ibm.com, linux@...ewoehner.de,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        jandryuk@...il.com, pmenzel@...gen.mpg.de, l.sanfilippo@...bus.com,
        LinoSanfilippo@....de, lukas@...ner.de, p.rosenberger@...bus.com
Subject: [PATCH v8 07/11] tpm, tpm_tis: do not check for the active locality in interrupt handler

From: Lino Sanfilippo <l.sanfilippo@...bus.com>

After driver initialization tpm_tis_data->locality may only be modified in
case of a LOCALITY CHANGE interrupt. In this case the interrupt handler
iterates over all localities only to assign the active one to
tpm_tis_data->locality.

However this information is never used any more, so the assignment is not
needed.
Furthermore without the assignment tpm_tis_data->locality cannot change any
more at driver runtime, and thus no protection against concurrent
modification is required when the variable is read at other places.

So remove this iteration entirely.

Signed-off-by: Lino Sanfilippo <l.sanfilippo@...bus.com>
---
 drivers/char/tpm/tpm_tis_core.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 181c291b0bb8..4336f7ea8c2b 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -728,7 +728,7 @@ static irqreturn_t tis_int_handler(int dummy, void *dev_id)
 	struct tpm_chip *chip = dev_id;
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
 	u32 interrupt;
-	int i, rc;
+	int rc;
 
 	rc = tpm_tis_read32(priv, TPM_INT_STATUS(priv->locality), &interrupt);
 	if (rc < 0)
@@ -740,10 +740,7 @@ static irqreturn_t tis_int_handler(int dummy, void *dev_id)
 	set_bit(TPM_TIS_IRQ_TESTED, &priv->flags);
 	if (interrupt & TPM_INTF_DATA_AVAIL_INT)
 		wake_up_interruptible(&priv->read_queue);
-	if (interrupt & TPM_INTF_LOCALITY_CHANGE_INT)
-		for (i = 0; i < 5; i++)
-			if (check_locality(chip, i))
-				break;
+
 	if (interrupt &
 	    (TPM_INTF_LOCALITY_CHANGE_INT | TPM_INTF_STS_VALID_INT |
 	     TPM_INTF_CMD_READY_INT))
-- 
2.36.1