crypto: drbg - make drbg_prepare_hrng() handle jent instantiation errors

Now that drbg_prepare_hrng() doesn't do anything but to instantiate a
jitterentropy crypto_rng instance, it looks a little odd to have the
related error handling at its only caller, drbg_instantiate().

Move the handling of jitterentropy allocation failures from
drbg_instantiate() close to the allocation itself in drbg_prepare_hrng().

There is no change in behaviour.
Signed-off-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Stephan Müller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/drbg.c

@@ -1516,6 +1516,14 @@ static int drbg_prepare_hrng(struct drbg_state *drbg)
 		return 0;
 
 	drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);
+	if (IS_ERR(drbg->jent)) {
+		const int err = PTR_ERR(drbg->jent);
+
+		drbg->jent = NULL;
+		if (fips_enabled || err != -ENOENT)
+			return err;
+		pr_info("DRBG: Continuing without Jitter RNG\n");
+	}
 
 	return 0;
 }
@@ -1571,14 +1579,6 @@ static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
 		if (ret)
 			goto free_everything;
 
-		if (IS_ERR(drbg->jent)) {
-			ret = PTR_ERR(drbg->jent);
-			drbg->jent = NULL;
-			if (fips_enabled || ret != -ENOENT)
-				goto free_everything;
-			pr_info("DRBG: Continuing without Jitter RNG\n");
-		}
-
 		reseed = false;
 	}