[PATCH net-next 16/20] tcp: avoid indirect calls to sock_rfree
From: Eric Dumazet <hidden>
Date: 2021-11-16 00:28:08
Subsystem:
networking [general], networking [tcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds
From: Eric Dumazet <edumazet@google.com> TCP uses sk_eat_skb() when skbs can be removed from receive queue. However, the call so 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> --- 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 9175e0d729f5e65b5fa39acadc5bf9de715854ad..4e7011672aa9a04370b7a03b972fe19cd48ea232 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);
--
2.34.0.rc1.387.gb447b232ab-goog