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Date:   Tue, 12 Dec 2023 11:12:55 +0100
From:   Ahelenia =?utf-8?Q?Ziemia=C5=84ska?= 
        <nabijaczleweli@nabijaczleweli.xyz>
To:     Eric Dumazet <edumazet@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        David Ahern <dsahern@kernel.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH RESEND 09/11] net/tcp: tcp_splice_read: always do
 non-blocking reads
Message-ID: <1d44f2f64c18151d103ee045d1e3ce7a7d5534273.1697486714.git.nabijaczleweli@nabijaczleweli.xyz>
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Otherwise we risk sleeping with the pipe locked for indeterminate
lengths of time.

sock_rcvtimeo() returns 0 if the second argument is true, so the
explicit re-try loop for empty read conditions can be removed
entirely.

Link: https://lore.kernel.org/linux-fsdevel/qk6hjuam54khlaikf2ssom6custxf5i=
s2ekkaequf4hvode3ls@zgf7j5j4ubvw/t/#u
Signed-off-by: Ahelenia Ziemia=C5=84ska <nabijaczleweli@nabijaczleweli.xyz>
---
 net/ipv4/tcp.c | 30 +++---------------------------
 1 file changed, 3 insertions(+), 27 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 3f66cdeef7de..09b562e2c1bf 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -782,7 +782,6 @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *pp=
os,
 		.len =3D len,
 		.flags =3D flags,
 	};
-	long timeo;
 	ssize_t spliced;
 	int ret;
=20
@@ -797,7 +796,6 @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *pp=
os,
=20
 	lock_sock(sk);
=20
-	timeo =3D sock_rcvtimeo(sk, sock->file->f_flags & O_NONBLOCK);
 	while (tss.len) {
 		ret =3D __tcp_splice_read(sk, &tss);
 		if (ret < 0)
@@ -821,35 +819,13 @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *=
ppos,
 				ret =3D -ENOTCONN;
 				break;
 			}
-			if (!timeo) {
-				ret =3D -EAGAIN;
-				break;
-			}
-			/* if __tcp_splice_read() got nothing while we have
-			 * an skb in receive queue, we do not want to loop.
-			 * This might happen with URG data.
-			 */
-			if (!skb_queue_empty(&sk->sk_receive_queue))
-				break;
-			sk_wait_data(sk, &timeo, NULL);
-			if (signal_pending(current)) {
-				ret =3D sock_intr_errno(timeo);
-				break;
-			}
-			continue;
+			ret =3D -EAGAIN;
+			break;
 		}
 		tss.len -=3D ret;
 		spliced +=3D ret;
=20
-		if (!tss.len || !timeo)
-			break;
-		release_sock(sk);
-		lock_sock(sk);
-
-		if (sk->sk_err || sk->sk_state =3D=3D TCP_CLOSE ||
-		    (sk->sk_shutdown & RCV_SHUTDOWN) ||
-		    signal_pending(current))
-			break;
+		break;
 	}
=20
 	release_sock(sk);
--=20
2.39.2

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