[RFC PATCH v2 net-next 09/12] net: don't bother calling list RX functions on empty lists
From: Edward Cree <hidden>
Date: 2018-06-26 18:21:06
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
Generally the check should be very cheap, as the sk_buff_head is in cache. Signed-off-by: Edward Cree <redacted> --- net/core/dev.c | 8 ++++++-- net/ipv4/ip_input.c | 2 ++ 2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index f0eb00e9fb57..11f80d4502b9 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c@@ -4780,7 +4780,8 @@ static void __netif_receive_skb_list(struct sk_buff_head *list) while ((skb = __skb_dequeue(list)) != NULL) { if ((sk_memalloc_socks() && skb_pfmemalloc(skb)) != pfmemalloc) { /* Handle the previous sublist */ - __netif_receive_skb_list_core(&sublist, pfmemalloc); + if (!skb_queue_empty(&sublist)) + __netif_receive_skb_list_core(&sublist, pfmemalloc); pfmemalloc = !pfmemalloc; /* See comments in __netif_receive_skb */ if (pfmemalloc)
@@ -4792,7 +4793,8 @@ static void __netif_receive_skb_list(struct sk_buff_head *list) __skb_queue_tail(&sublist, skb); } /* Handle the last sublist */ - __netif_receive_skb_list_core(&sublist, pfmemalloc); + if (!skb_queue_empty(&sublist)) + __netif_receive_skb_list_core(&sublist, pfmemalloc); /* Restore pflags */ if (pfmemalloc) memalloc_noreclaim_restore(noreclaim_flag);
@@ -4968,6 +4970,8 @@ void netif_receive_skb_list(struct sk_buff_head *list) { struct sk_buff *skb; + if (skb_queue_empty(list)) + return; skb_queue_for_each(skb, list) trace_netif_receive_skb_list_entry(skb); netif_receive_skb_list_internal(list);
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 63d4dfdb1766..65a5ed9e4b3c 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c@@ -570,6 +570,8 @@ static void ip_sublist_rcv(struct sk_buff_head *list, struct net_device *dev, { struct sk_buff_head sublist; + if (skb_queue_empty(list)) + return; NF_HOOK_LIST(NFPROTO_IPV4, NF_INET_PRE_ROUTING, net, NULL, list, &sublist, dev, NULL, ip_rcv_finish); ip_list_rcv_finish(net, NULL, &sublist);