From 88eb1944e18c1ba61da538ae9d1732832eb79b9d Mon Sep 17 00:00:00 2001 From: Edward Cree Date: Mon, 2 Jul 2018 16:13:56 +0100 Subject: [PATCH] net: core: propagate SKB lists through packet_type lookup __netif_receive_skb_core() does a depressingly large amount of per-packet work that can't easily be listified, because the another_round looping makes it nontrivial to slice up into smaller functions. Fortunately, most of that work disappears in the fast path: * Hardware devices generally don't have an rx_handler * Unless you're tcpdumping or something, there is usually only one ptype * VLAN processing comes before the protocol ptype lookup, so doesn't force a pt_prev deliver so normally, __netif_receive_skb_core() will run straight through and pass back the one ptype found in ptype_base[hash of skb->protocol]. Signed-off-by: Edward Cree Signed-off-by: David S. Miller --- net/core/dev.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 64 insertions(+), 8 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 9aadef9..1bc485b 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4608,7 +4608,8 @@ static inline int nf_ingress(struct sk_buff *skb, struct packet_type **pt_prev, return 0; } -static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc) +static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc, + struct packet_type **ppt_prev) { struct packet_type *ptype, *pt_prev; rx_handler_func_t *rx_handler; @@ -4738,8 +4739,7 @@ skip_classify: if (pt_prev) { if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC))) goto drop; - else - ret = pt_prev->func(skb, skb->dev, pt_prev, orig_dev); + *ppt_prev = pt_prev; } else { drop: if (!deliver_exact) @@ -4757,6 +4757,18 @@ out: return ret; } +static int __netif_receive_skb_one_core(struct sk_buff *skb, bool pfmemalloc) +{ + struct net_device *orig_dev = skb->dev; + struct packet_type *pt_prev = NULL; + int ret; + + ret = __netif_receive_skb_core(skb, pfmemalloc, &pt_prev); + if (pt_prev) + ret = pt_prev->func(skb, skb->dev, pt_prev, orig_dev); + return ret; +} + /** * netif_receive_skb_core - special purpose version of netif_receive_skb * @skb: buffer to process @@ -4777,19 +4789,63 @@ int netif_receive_skb_core(struct sk_buff *skb) int ret; rcu_read_lock(); - ret = __netif_receive_skb_core(skb, false); + ret = __netif_receive_skb_one_core(skb, false); rcu_read_unlock(); return ret; } EXPORT_SYMBOL(netif_receive_skb_core); -static void __netif_receive_skb_list_core(struct list_head *head, bool pfmemalloc) +static inline void __netif_receive_skb_list_ptype(struct list_head *head, + struct packet_type *pt_prev, + struct net_device *orig_dev) { struct sk_buff *skb, *next; + if (!pt_prev) + return; + if (list_empty(head)) + return; + list_for_each_entry_safe(skb, next, head, list) - __netif_receive_skb_core(skb, pfmemalloc); + pt_prev->func(skb, skb->dev, pt_prev, orig_dev); +} + +static void __netif_receive_skb_list_core(struct list_head *head, bool pfmemalloc) +{ + /* Fast-path assumptions: + * - There is no RX handler. + * - Only one packet_type matches. + * If either of these fails, we will end up doing some per-packet + * processing in-line, then handling the 'last ptype' for the whole + * sublist. This can't cause out-of-order delivery to any single ptype, + * because the 'last ptype' must be constant across the sublist, and all + * other ptypes are handled per-packet. + */ + /* Current (common) ptype of sublist */ + struct packet_type *pt_curr = NULL; + /* Current (common) orig_dev of sublist */ + struct net_device *od_curr = NULL; + struct list_head sublist; + struct sk_buff *skb, *next; + + list_for_each_entry_safe(skb, next, head, list) { + struct net_device *orig_dev = skb->dev; + struct packet_type *pt_prev = NULL; + + __netif_receive_skb_core(skb, pfmemalloc, &pt_prev); + if (pt_curr != pt_prev || od_curr != orig_dev) { + /* dispatch old sublist */ + list_cut_before(&sublist, head, &skb->list); + __netif_receive_skb_list_ptype(&sublist, pt_curr, od_curr); + /* start new sublist */ + pt_curr = pt_prev; + od_curr = orig_dev; + } + } + + /* dispatch final sublist */ + __netif_receive_skb_list_ptype(head, pt_curr, od_curr); } static int __netif_receive_skb(struct sk_buff *skb) @@ -4809,10 +4865,10 @@ static int __netif_receive_skb(struct sk_buff *skb) * context down to all allocation sites. */ noreclaim_flag = memalloc_noreclaim_save(); - ret = __netif_receive_skb_core(skb, true); + ret = __netif_receive_skb_one_core(skb, true); memalloc_noreclaim_restore(noreclaim_flag); } else - ret = __netif_receive_skb_core(skb, false); + ret = __netif_receive_skb_one_core(skb, false); return ret; } -- 2.7.4