crypto: xts - simplify error handling in ->create()

Simplify the error handling in the XTS template's ->create() function by
taking advantage of crypto_drop_skcipher() now accepting (as a no-op) a
spawn that hasn't been grabbed yet.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/xts.c

@@ -379,15 +379,15 @@ static int create(struct crypto_template *tmpl, struct rtattr **tb)
 
 	err = -EINVAL;
 	if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
-		goto err_drop_spawn;
+		goto err_free_inst;
 
 	if (crypto_skcipher_alg_ivsize(alg))
-		goto err_drop_spawn;
+		goto err_free_inst;
 
 	err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
 				  &alg->base);
 	if (err)
-		goto err_drop_spawn;
+		goto err_free_inst;
 
 	err = -EINVAL;
 	cipher_name = alg->base.cra_name;
@@ -400,20 +400,20 @@ static int create(struct crypto_template *tmpl, struct rtattr **tb)
 
 		len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
 		if (len < 2 || len >= sizeof(ctx->name))
-			goto err_drop_spawn;
+			goto err_free_inst;
 
 		if (ctx->name[len - 1] != ')')
-			goto err_drop_spawn;
+			goto err_free_inst;
 
 		ctx->name[len - 1] = 0;
 
 		if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 			     "xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME) {
 			err = -ENAMETOOLONG;
-			goto err_drop_spawn;
+			goto err_free_inst;
 		}
 	} else
-		goto err_drop_spawn;
+		goto err_free_inst;
 
 	inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
 	inst->alg.base.cra_priority = alg->base.cra_priority;
@@ -437,17 +437,11 @@ static int create(struct crypto_template *tmpl, struct rtattr **tb)
 	inst->free = free;
 
 	err = skcipher_register_instance(tmpl, inst);
-	if (err)
-		goto err_drop_spawn;
-
-out:
-	return err;
-
-err_drop_spawn:
-	crypto_drop_skcipher(&ctx->spawn);
+	if (err) {
 err_free_inst:
-	kfree(inst);
-	goto out;
+		free(inst);
+	}
+	return err;
 }
 
 static struct crypto_template crypto_tmpl = {