linux-kernel - [PATCH 5.4 263/340] tpm_tis: Clean up locality release

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Date:   Mon,  1 Mar 2021 17:13:27 +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, stable@....kernel.org,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        Jarkko Sakkinen <jarkko@...nel.org>
Subject: [PATCH 5.4 263/340] tpm_tis: Clean up locality release

From: James Bottomley <James.Bottomley@...senPartnership.com>

commit e42acf104d6e0bd7ccd2f09103d5be5e6d3c637c upstream.

The current release locality code seems to be based on the
misunderstanding that the TPM interrupts when a locality is released:
it doesn't, only when the locality is acquired.

Furthermore, there seems to be no point in waiting for the locality to
be released.  All it does is penalize the last TPM user.  However, if
there's no next TPM user, this is a pointless wait and if there is a
next TPM user, they'll pay the penalty waiting for the new locality
(or possibly not if it's the same as the old locality).

Fix the code by making release_locality as simple write to release
with no waiting for completion.

Cc: stable@....kernel.org
Fixes: 33bafe90824b ("tpm_tis: verify locality released before returning from release_locality")
Signed-off-by: James Bottomley <James.Bottomley@...senPartnership.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@...hat.com>
Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/char/tpm/tpm_tis_core.c |   47 ----------------------------------------
 1 file changed, 1 insertion(+), 46 deletions(-)

--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -135,58 +135,13 @@ static bool check_locality(struct tpm_ch
 	return false;
 }
 
-static bool locality_inactive(struct tpm_chip *chip, int l)
-{
-	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
-	int rc;
-	u8 access;
-
-	rc = tpm_tis_read8(priv, TPM_ACCESS(l), &access);
-	if (rc < 0)
-		return false;
-
-	if ((access & (TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY))
-	    == TPM_ACCESS_VALID)
-		return true;
-
-	return false;
-}
-
 static int release_locality(struct tpm_chip *chip, int l)
 {
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
-	unsigned long stop, timeout;
-	long rc;
 
 	tpm_tis_write8(priv, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
 
-	stop = jiffies + chip->timeout_a;
-
-	if (chip->flags & TPM_CHIP_FLAG_IRQ) {
-again:
-		timeout = stop - jiffies;
-		if ((long)timeout <= 0)
-			return -1;
-
-		rc = wait_event_interruptible_timeout(priv->int_queue,
-						      (locality_inactive(chip, l)),
-						      timeout);
-
-		if (rc > 0)
-			return 0;
-
-		if (rc == -ERESTARTSYS && freezing(current)) {
-			clear_thread_flag(TIF_SIGPENDING);
-			goto again;
-		}
-	} else {
-		do {
-			if (locality_inactive(chip, l))
-				return 0;
-			tpm_msleep(TPM_TIMEOUT);
-		} while (time_before(jiffies, stop));
-	}
-	return -1;
+	return 0;
 }
 
 static int request_locality(struct tpm_chip *chip, int l)