From 3665f3817cd354ab7a811b3a4f282c4f5cb1a0d0 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 7 Dec 2016 10:05:36 -0800 Subject: [PATCH] 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 Cc: Paolo Abeni Signed-off-by: David S. Miller --- include/net/sock.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/include/net/sock.h b/include/net/sock.h index 2729e77950b7..e17aa3de2b4d 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -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)