Commit 3665f381 authored Dec 07, 2016 by Eric Dumazet Committed by David S. Miller Dec 08, 2016

net: do not read sk_drops if application does not care



sk_drops can be an often written field, do not read it unless
application showed interest.

Note that sk_drops can be read via inet_diag, so applications
can avoid getting this info from every received packet.

In the future, 'reading' sk_drops might require folding per node or per
cpu fields, and thus become even more expensive than today.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent c8c8b127

include/net/sock.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -2163,7 +2163,8 @@ struct sock_skb_cb {
		static inline void
		sock_skb_set_dropcount(const struct sock sk, struct sk_buff skb)
		{
		SOCK_SKB_CB(skb)->dropcount = atomic_read(&sk->sk_drops);
		SOCK_SKB_CB(skb)->dropcount = sock_flag(sk, SOCK_RXQ_OVFL) ?
		atomic_read(&sk->sk_drops) : 0;
		}

		static inline void sk_drops_add(struct sock sk, const struct sk_buff skb)