Commit 3df684c1 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: avoid indirect calls to sock_rfree 



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: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b96c51bd

net/ipv4/tcp.c

+15 −5
Original line number Diff line number Diff line
@@ -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);