netdev - [PATCH net-next 3/4] udp: avoid calling sock_def

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240328144032.1864988-4-edumazet@google.com>
Date: Thu, 28 Mar 2024 14:40:31 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: Willem de Bruijn <willemb@...gle.com>, netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 3/4] udp: avoid calling sock_def_readable() if possible

sock_def_readable() is quite expensive (particularly
when ep_poll_callback() is in the picture).

We must call sk->sk_data_ready() when :

- receive queue was empty, or
- SO_PEEK_OFF is enabled on the socket, or
- sk->sk_data_ready is not sock_def_readable.

We still need to call sk_wake_async().

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/udp.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index d2fa9755727ce034c2b4bca82bd9e72130d588e6..5dfbe4499c0f89f94af9ee1fb64559dd672c1439 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1492,6 +1492,7 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb)
 	struct sk_buff_head *list = &sk->sk_receive_queue;
 	int rmem, err = -ENOMEM;
 	spinlock_t *busy = NULL;
+	bool becomes_readable;
 	int size, rcvbuf;
 
 	/* Immediately drop when the receive queue is full.
@@ -1532,12 +1533,19 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb)
 	 */
 	sock_skb_set_dropcount(sk, skb);
 
+	becomes_readable = skb_queue_empty(list);
 	__skb_queue_tail(list, skb);
 	spin_unlock(&list->lock);
 
-	if (!sock_flag(sk, SOCK_DEAD))
-		INDIRECT_CALL_1(sk->sk_data_ready, sock_def_readable, sk);
-
+	if (!sock_flag(sk, SOCK_DEAD)) {
+		if (becomes_readable ||
+		    sk->sk_data_ready != sock_def_readable ||
+		    READ_ONCE(sk->sk_peek_off) >= 0)
+			INDIRECT_CALL_1(sk->sk_data_ready,
+					sock_def_readable, sk);
+		else
+			sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
+	}
 	busylock_release(busy);
 	return 0;
 
-- 
2.44.0.396.g6e790dbe36-goog