dm-crypt: use crypto_shash_digest() in crypt_iv_tcw_whitening()

index 5315fd261c23..32d230e3180d 100644
@@ -645,27 +645,21 @@ static int crypt_iv_tcw_whitening(struct crypt_config *cc,
 	SHASH_DESC_ON_STACK(desc, tcw->crc32_tfm);
 	int i, r;
 
 	/* xor whitening with sector number */
 	crypto_xor_cpy(buf, tcw->whitening, (u8 *)&sector, 8);
 	crypto_xor_cpy(&buf[8], tcw->whitening + 8, (u8 *)&sector, 8);
 
 	/* calculate crc32 for every 32bit part and xor it */
 	desc->tfm = tcw->crc32_tfm;
 	for (i = 0; i < 4; i++) {
-		r = crypto_shash_init(desc);
-		if (r)
-			goto out;
-		r = crypto_shash_update(desc, &buf[i * 4], 4);
-		if (r)
-			goto out;
-		r = crypto_shash_final(desc, &buf[i * 4]);
+		r = crypto_shash_digest(desc, &buf[i * 4], 4, &buf[i * 4]);
 		if (r)
 			goto out;
 	}
 	crypto_xor(&buf[0], &buf[12], 4);
 	crypto_xor(&buf[4], &buf[8], 4);
 
 	/* apply whitening (8 bytes) to whole sector */
 	for (i = 0; i < ((1 << SECTOR_SHIFT) / 8); i++)
 		crypto_xor(data + i * 8, buf, 8);
 out: