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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: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2021-11-15 11:02:45 -08:00 committed by David S. Miller
parent b96c51bd3b
commit 3df684c1a3
1 changed files with 15 additions and 5 deletions
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20
net/ipv4/tcp.c
View File

@ -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);