crypto: drbg - move to generic async completion

DRBG is starting an async. crypto op and waiting for it complete.
Move it over to generic code doing the same.

The code now also passes CRYPTO_TFM_REQ_MAY_SLEEP flag indicating
crypto request memory allocation may use GFP_KERNEL which should
be perfectly fine as the code is obviously sleeping for the
completion of the request any way.
Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/drbg.c

@@ -1651,16 +1651,6 @@ static int drbg_fini_sym_kernel(struct drbg_state *drbg)
 	return 0;
 }
 
-static void drbg_skcipher_cb(struct crypto_async_request *req, int error)
-{
-	struct drbg_state *drbg = req->data;
-
-	if (error == -EINPROGRESS)
-		return;
-	drbg->ctr_async_err = error;
-	complete(&drbg->ctr_completion);
-}
-
 static int drbg_init_sym_kernel(struct drbg_state *drbg)
 {
 	struct crypto_cipher *tfm;
@@ -1691,7 +1681,7 @@ static int drbg_init_sym_kernel(struct drbg_state *drbg)
 		return PTR_ERR(sk_tfm);
 	}
 	drbg->ctr_handle = sk_tfm;
-	init_completion(&drbg->ctr_completion);
+	crypto_init_wait(&drbg->ctr_wait);
 
 	req = skcipher_request_alloc(sk_tfm, GFP_KERNEL);
 	if (!req) {
@@ -1700,8 +1690,9 @@ static int drbg_init_sym_kernel(struct drbg_state *drbg)
 		return -ENOMEM;
 	}
 	drbg->ctr_req = req;
-	skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
-					drbg_skcipher_cb, drbg);
+	skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
+						CRYPTO_TFM_REQ_MAY_SLEEP,
+					crypto_req_done, &drbg->ctr_wait);
 
 	alignmask = crypto_skcipher_alignmask(sk_tfm);
 	drbg->ctr_null_value_buf = kzalloc(DRBG_CTR_NULL_LEN + alignmask,
@@ -1762,21 +1753,12 @@ static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
 		/* Output buffer may not be valid for SGL, use scratchpad */
 		skcipher_request_set_crypt(drbg->ctr_req, &sg_in, &sg_out,
 					   cryptlen, drbg->V);
-		ret = crypto_skcipher_encrypt(drbg->ctr_req);
-		switch (ret) {
-		case 0:
-			break;
-		case -EINPROGRESS:
-		case -EBUSY:
-			wait_for_completion(&drbg->ctr_completion);
-			if (!drbg->ctr_async_err) {
-				reinit_completion(&drbg->ctr_completion);
-				break;
-			}
-		default:
+		ret = crypto_wait_req(crypto_skcipher_encrypt(drbg->ctr_req),
+					&drbg->ctr_wait);
+		if (ret)
 			goto out;
-		}
-		init_completion(&drbg->ctr_completion);
+
+		crypto_init_wait(&drbg->ctr_wait);
 
 		memcpy(outbuf, drbg->outscratchpad, cryptlen);
 

include/crypto/drbg.h

@@ -126,8 +126,7 @@ struct drbg_state {
 	__u8 *ctr_null_value;			/* CTR mode aligned zero buf */
 	__u8 *outscratchpadbuf;			/* CTR mode output scratchpad */
         __u8 *outscratchpad;			/* CTR mode aligned outbuf */
-	struct completion ctr_completion;	/* CTR mode async handler */
-	int ctr_async_err;			/* CTR mode async error */
+	struct crypto_wait ctr_wait;		/* CTR mode async wait obj */
 
 	bool seeded;		/* DRBG fully seeded? */
 	bool pr;		/* Prediction resistance enabled? */