From 3df684c1a3d08a4f649689053a3d527b3b5fda9e Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Mon, 15 Nov 2021 11:02:45 -0800
Subject: [PATCH] tcp: avoid indirect calls to sock_rfree
Git-commit: 3df684c1a3d08a4f649689053a3d527b3b5fda9e
Patch-mainline: v5.15
References: bsc#1195400

TCP uses sk_eat_skb() when skbs can be removed from receive queue.
However, the call to skb_orphan() from __kfree_skb() incurs
an indirect call so sock_rfee(), which is more expensive than
a direct call, especially for CONFIG_RETPOLINE=y.

Add tcp_eat_recv_skb() function to make the call before
__kfree_skb().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Wiesner <jwiesner@suse.de>
---
 net/ipv4/tcp.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 9175e0d729f5..4e7011672aa9 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1580,6 +1580,16 @@ void tcp_cleanup_rbuf(struct sock *sk, int copied)
 		tcp_send_ack(sk);
 }
 
+static void tcp_eat_recv_skb(struct sock *sk, struct sk_buff *skb)
+{
+	if (likely(skb->destructor == sock_rfree)) {
+		sock_rfree(skb);
+		skb->destructor = NULL;
+		skb->sk = NULL;
+	}
+	sk_eat_skb(sk, skb);
+}
+
 static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
 {
 	struct sk_buff *skb;
@@ -1599,7 +1609,7 @@ static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
 		 * splitted a fat GRO packet, while we released socket lock
 		 * in skb_splice_bits()
 		 */
-		sk_eat_skb(sk, skb);
+		tcp_eat_recv_skb(sk, skb);
 	}
 	return NULL;
 }
@@ -1665,11 +1675,11 @@ int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
 				continue;
 		}
 		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {
-			sk_eat_skb(sk, skb);
+			tcp_eat_recv_skb(sk, skb);
 			++seq;
 			break;
 		}
-		sk_eat_skb(sk, skb);
+		tcp_eat_recv_skb(sk, skb);
 		if (!desc->count)
 			break;
 		WRITE_ONCE(tp->copied_seq, seq);
@@ -2481,14 +2491,14 @@ static int tcp_recvmsg_locked(struct sock *sk, struct msghdr *msg, size_t len,
 		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
 			goto found_fin_ok;
 		if (!(flags & MSG_PEEK))
-			sk_eat_skb(sk, skb);
+			tcp_eat_recv_skb(sk, skb);
 		continue;
 
 found_fin_ok:
 		/* Process the FIN. */
 		WRITE_ONCE(*seq, *seq + 1);
 		if (!(flags & MSG_PEEK))
-			sk_eat_skb(sk, skb);
+			tcp_eat_recv_skb(sk, skb);
 		break;
 	} while (len > 0);
 
-- 
2.26.2