tls: Fix tls_sw_sendmsg error handling

We've noticed that NFS can hang when using RPC over TLS on an unstable
connection, and investigation shows that the RPC layer is stuck in a tight
loop attempting to transmit, but forever getting -EBADMSG back from the
underlying network.  The loop begins when tcp_sendmsg_locked() returns
-EPIPE to tls_tx_records(), but that error is converted to -EBADMSG when
calling the socket's error reporting handler.

Instead of converting errors from tcp_sendmsg_locked(), let's pass them
along in this path.  The RPC layer handles -EPIPE by reconnecting the
transport, which prevents the endless attempts to transmit on a broken
connection.

Signed-off-by: Benjamin Coddington <[email protected]>
Fixes: a42055e ("net/tls: Add support for async encryption of records for performance")
Link: https://patch.msgid.link/9594185559881679d81f071b181a10eb07cd079f.1736004079.git.bcodding@redhat.com
Signed-off-by: Jakub Kicinski <[email protected]>

net/tls/tls_sw.c

@@ -458,7 +458,7 @@ int tls_tx_records(struct sock *sk, int flags)
 
 tx_err:
 	if (rc < 0 && rc != -EAGAIN)
-		tls_err_abort(sk, -EBADMSG);
+		tls_err_abort(sk, rc);
 
 	return rc;
 }