tls: rx: factor out device darg update

I already forgot to transform darg from input to output
semantics once on the NIC inline crypto fastpath. To
avoid this happening again create a device equivalent
of decrypt_internal(). A function responsible for decryption
and transforming darg.

While at it rename decrypt_internal() to a hopefully slightly
more meaningful name.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tls/tls_sw.c

@@ -1404,18 +1404,27 @@ static int tls_setup_from_iter(struct iov_iter *from,
 	return rc;
 }
 
+/* Decrypt handlers
+ *
+ * tls_decrypt_sg() and tls_decrypt_device() are decrypt handlers.
+ * They must transform the darg in/out argument are as follows:
+ *       |          Input            |         Output
+ * -------------------------------------------------------------------
+ *    zc | Zero-copy decrypt allowed | Zero-copy performed
+ * async | Async decrypt allowed     | Async crypto used / in progress
+ */
+
 /* This function decrypts the input skb into either out_iov or in out_sg
- * or in skb buffers itself. The input parameter 'zc' indicates if
+ * or in skb buffers itself. The input parameter 'darg->zc' indicates if
  * zero-copy mode needs to be tried or not. With zero-copy mode, either
  * out_iov or out_sg must be non-NULL. In case both out_iov and out_sg are
  * NULL, then the decryption happens inside skb buffers itself, i.e.
- * zero-copy gets disabled and 'zc' is updated.
+ * zero-copy gets disabled and 'darg->zc' is updated.
  */
-
-static int decrypt_internal(struct sock *sk, struct sk_buff *skb,
-			    struct iov_iter *out_iov,
-			    struct scatterlist *out_sg,
-			    struct tls_decrypt_arg *darg)
+static int tls_decrypt_sg(struct sock *sk, struct sk_buff *skb,
+			  struct iov_iter *out_iov,
+			  struct scatterlist *out_sg,
+			  struct tls_decrypt_arg *darg)
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct tls_sw_context_rx *ctx = tls_sw_ctx_rx(tls_ctx);
@@ -1556,6 +1565,24 @@ static int decrypt_internal(struct sock *sk, struct sk_buff *skb,
 	return err;
 }
 
+static int
+tls_decrypt_device(struct sock *sk, struct tls_context *tls_ctx,
+		   struct sk_buff *skb, struct tls_decrypt_arg *darg)
+{
+	int err;
+
+	if (tls_ctx->rx_conf != TLS_HW)
+		return 0;
+
+	err = tls_device_decrypted(sk, tls_ctx, skb, strp_msg(skb));
+	if (err <= 0)
+		return err;
+
+	darg->zc = false;
+	darg->async = false;
+	return 1;
+}
+
 static int decrypt_skb_update(struct sock *sk, struct sk_buff *skb,
 			      struct iov_iter *dest,
 			      struct tls_decrypt_arg *darg)
@@ -1565,18 +1592,13 @@ static int decrypt_skb_update(struct sock *sk, struct sk_buff *skb,
 	struct strp_msg *rxm = strp_msg(skb);
 	int pad, err;
 
-	if (tls_ctx->rx_conf == TLS_HW) {
-		err = tls_device_decrypted(sk, tls_ctx, skb, rxm);
-		if (err < 0)
-			return err;
-		if (err > 0) {
-			darg->zc = false;
-			darg->async = false;
-			goto decrypt_done;
-		}
-	}
+	err = tls_decrypt_device(sk, tls_ctx, skb, darg);
+	if (err < 0)
+		return err;
+	if (err)
+		goto decrypt_done;
 
-	err = decrypt_internal(sk, skb, dest, NULL, darg);
+	err = tls_decrypt_sg(sk, skb, dest, NULL, darg);
 	if (err < 0) {
 		if (err == -EBADMSG)
 			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSDECRYPTERROR);
@@ -1613,7 +1635,7 @@ int decrypt_skb(struct sock *sk, struct sk_buff *skb,
 {
 	struct tls_decrypt_arg darg = { .zc = true, };
 
-	return decrypt_internal(sk, skb, NULL, sgout, &darg);
+	return tls_decrypt_sg(sk, skb, NULL, sgout, &darg);
 }
 
 static int tls_record_content_type(struct msghdr *msg, struct tls_msg *tlm,