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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 <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Edward Cree 2018-07-02 16:13:56 +01:00 committed by David S. Miller
parent 4ce0017a37
commit 88eb1944e1
1 changed files with 64 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

72
net/core/dev.c
View File

@ -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;
}