crypto: qat - disable registration of algorithms

The implementations of aead and skcipher in the QAT driver do not
support properly requests with the CRYPTO_TFM_REQ_MAY_BACKLOG flag set.
If the HW queue is full, the driver returns -EBUSY but does not enqueue
the request.
This can result in applications like dm-crypt waiting indefinitely for a
completion of a request that was never submitted to the hardware.

To avoid this problem, disable the registration of all crypto algorithms
in the QAT driver by setting the number of crypto instances to 0 at
configuration time.

Cc: stable@vger.kernel.org
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/qat/qat_4xxx/adf_drv.c

@@ -75,6 +75,13 @@ static int adf_crypto_dev_config(struct adf_accel_dev *accel_dev)
 	if (ret)
 		goto err;
 
+	/* Temporarily set the number of crypto instances to zero to avoid
+	 * registering the crypto algorithms.
+	 * This will be removed when the algorithms will support the
+	 * CRYPTO_TFM_REQ_MAY_BACKLOG flag
+	 */
+	instances = 0;
+
 	for (i = 0; i < instances; i++) {
 		val = i;
 		bank = i * 2;

drivers/crypto/qat/qat_common/qat_crypto.c

@@ -161,6 +161,13 @@ int qat_crypto_dev_config(struct adf_accel_dev *accel_dev)
 	if (ret)
 		goto err;
 
+	/* Temporarily set the number of crypto instances to zero to avoid
+	 * registering the crypto algorithms.
+	 * This will be removed when the algorithms will support the
+	 * CRYPTO_TFM_REQ_MAY_BACKLOG flag
+	 */
+	instances = 0;
+
 	for (i = 0; i < instances; i++) {
 		val = i;
 		snprintf(key, sizeof(key), ADF_CY "%d" ADF_RING_ASYM_BANK_NUM, i);