[PATCH PATCH net-next v4 6/8] tls: Flush backlog before waiting for a new record

From: Chuck Lever <[email protected]>

While lock_sock is held, incoming TCP segments land on
sk->sk_backlog rather than sk->sk_receive_queue.
tls_rx_rec_wait() inspects only sk_receive_queue, so
backlog data remains invisible. For non-blocking callers
(read_sock, and recvmsg or splice_read with MSG_DONTWAIT)
this causes a spurious -EAGAIN. For blocking callers it
forces an unnecessary sleep/wakeup cycle.

Flush the backlog inside tls_rx_rec_wait() before checking
sk_receive_queue so the strparser can parse newly-arrived
segments immediately.

Suggested-by: Sabrina Dubroca <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Signed-off-by: Chuck Lever <[email protected]>
---
 net/tls/tls_sw.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 381a723b6cacc669e333752af34f051f296d6f52..5b154afbd7ac2ddd51b46d8d6bef0a7a41f0a841 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -1383,6 +1383,7 @@ tls_rx_rec_wait(struct sock *sk, struct sk_psock *psock, bool nonblock,
 		if (ret < 0)
 			return ret;
 
+		sk_flush_backlog(sk);
 		if (!skb_queue_empty(&sk->sk_receive_queue)) {
 			/* tls_strp_check_rcv() is called at each receive
 			 * path's exit before the socket lock is released.

-- 
2.53.0