net/tls: split tls_rx_reader_lock

Split tls_rx_reader_{lock,unlock} into an 'acquire/release' and
the actual locking part.
With that we can use the tls_rx_reader_lock in situations where
the socket is already locked.
Suggested-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20230726191556.41714-6-hare@suse.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/tls/tls_sw.c

@@ -1848,13 +1848,10 @@ tls_read_flush_backlog(struct sock *sk, struct tls_prot_info *prot,
 	return sk_flush_backlog(sk);
 }
 
-static int tls_rx_reader_lock(struct sock *sk, struct tls_sw_context_rx *ctx,
-			      bool nonblock)
+static int tls_rx_reader_acquire(struct sock *sk, struct tls_sw_context_rx *ctx,
+				 bool nonblock)
 {
 	long timeo;
-	int err;
-
-	lock_sock(sk);
 
 	timeo = sock_rcvtimeo(sk, nonblock);
 
@@ -1868,26 +1865,30 @@ static int tls_rx_reader_lock(struct sock *sk, struct tls_sw_context_rx *ctx,
 			      !READ_ONCE(ctx->reader_present), &wait);
 		remove_wait_queue(&ctx->wq, &wait);
 
-		if (timeo <= 0) {
-			err = -EAGAIN;
-			goto err_unlock;
-		}
-		if (signal_pending(current)) {
-			err = sock_intr_errno(timeo);
-			goto err_unlock;
-		}
+		if (timeo <= 0)
+			return -EAGAIN;
+		if (signal_pending(current))
+			return sock_intr_errno(timeo);
 	}
 
 	WRITE_ONCE(ctx->reader_present, 1);
 
 	return 0;
+}
 
-err_unlock:
-	release_sock(sk);
+static int tls_rx_reader_lock(struct sock *sk, struct tls_sw_context_rx *ctx,
+			      bool nonblock)
+{
+	int err;
+
+	lock_sock(sk);
+	err = tls_rx_reader_acquire(sk, ctx, nonblock);
+	if (err)
+		release_sock(sk);
 	return err;
 }
 
-static void tls_rx_reader_unlock(struct sock *sk, struct tls_sw_context_rx *ctx)
+static void tls_rx_reader_release(struct sock *sk, struct tls_sw_context_rx *ctx)
 {
 	if (unlikely(ctx->reader_contended)) {
 		if (wq_has_sleeper(&ctx->wq))
@@ -1899,6 +1900,11 @@ static void tls_rx_reader_unlock(struct sock *sk, struct tls_sw_context_rx *ctx)
 	}
 
 	WRITE_ONCE(ctx->reader_present, 0);
+}
+
+static void tls_rx_reader_unlock(struct sock *sk, struct tls_sw_context_rx *ctx)
+{
+	tls_rx_reader_release(sk, ctx);
 	release_sock(sk);
 }