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Date: Tue, 19 Apr 2016 14:36:30 +0100
From: Edward Cree <ecree@...arflare.com>
To: <netdev@...r.kernel.org>, David Miller <davem@...emloft.net>
CC: Jesper Dangaard Brouer <brouer@...hat.com>,
<linux-net-drivers@...arflare.com>
Subject: [RFC PATCH net-next 6/8] net: core: propagate SKB lists through
packet_type lookup
This could maybe be made more efficient if we first split the list based on
skb->protocol, and then did ptype lookup for each sublist. Unfortunately,
there are things liks sch_handle_ingress and the rx_handlers that can
produce different results per packet.
Signed-off-by: Edward Cree <ecree@...arflare.com>
---
include/trace/events/net.h | 7 +++
net/core/dev.c | 146 ++++++++++++++++++++++++++++++++-------------
2 files changed, 113 insertions(+), 40 deletions(-)
diff --git a/include/trace/events/net.h b/include/trace/events/net.h
index 30f359c..7a17a31 100644
--- a/include/trace/events/net.h
+++ b/include/trace/events/net.h
@@ -130,6 +130,13 @@ DEFINE_EVENT(net_dev_template, netif_receive_skb,
TP_ARGS(skb)
);
+DEFINE_EVENT(net_dev_template, netif_receive_skb_list,
+
+ TP_PROTO(struct sk_buff *skb),
+
+ TP_ARGS(skb)
+);
+
DEFINE_EVENT(net_dev_template, netif_rx,
TP_PROTO(struct sk_buff *skb),
diff --git a/net/core/dev.c b/net/core/dev.c
index 0f914bf..db1d16a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4061,12 +4061,13 @@ 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_taps(struct sk_buff *skb, bool pfmemalloc,
+ struct packet_type **pt_prev)
{
- struct packet_type *ptype, *pt_prev;
rx_handler_func_t *rx_handler;
struct net_device *orig_dev;
bool deliver_exact = false;
+ struct packet_type *ptype;
int ret = NET_RX_DROP;
__be16 type;
@@ -4081,7 +4082,7 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
skb_reset_transport_header(skb);
skb_reset_mac_len(skb);
- pt_prev = NULL;
+ *pt_prev = NULL;
another_round:
skb->skb_iif = skb->dev->ifindex;
@@ -4106,25 +4107,25 @@ another_round:
goto skip_taps;
list_for_each_entry_rcu(ptype, &ptype_all, list) {
- if (pt_prev)
- ret = deliver_skb(skb, pt_prev, orig_dev);
- pt_prev = ptype;
+ if (*pt_prev)
+ ret = deliver_skb(skb, *pt_prev, orig_dev);
+ *pt_prev = ptype;
}
list_for_each_entry_rcu(ptype, &skb->dev->ptype_all, list) {
- if (pt_prev)
- ret = deliver_skb(skb, pt_prev, orig_dev);
- pt_prev = ptype;
+ if (*pt_prev)
+ ret = deliver_skb(skb, *pt_prev, orig_dev);
+ *pt_prev = ptype;
}
skip_taps:
#ifdef CONFIG_NET_INGRESS
if (static_key_false(&ingress_needed)) {
- skb = sch_handle_ingress(skb, &pt_prev, &ret, orig_dev);
+ skb = sch_handle_ingress(skb, pt_prev, &ret, orig_dev);
if (!skb)
goto out;
- if (nf_ingress(skb, &pt_prev, &ret, orig_dev) < 0)
+ if (nf_ingress(skb, pt_prev, &ret, orig_dev) < 0)
goto out;
}
#endif
@@ -4136,9 +4137,9 @@ ncls:
goto drop;
if (skb_vlan_tag_present(skb)) {
- if (pt_prev) {
- ret = deliver_skb(skb, pt_prev, orig_dev);
- pt_prev = NULL;
+ if (*pt_prev) {
+ ret = deliver_skb(skb, *pt_prev, orig_dev);
+ *pt_prev = NULL;
}
if (vlan_do_receive(&skb))
goto another_round;
@@ -4148,9 +4149,9 @@ ncls:
rx_handler = rcu_dereference(skb->dev->rx_handler);
if (rx_handler) {
- if (pt_prev) {
- ret = deliver_skb(skb, pt_prev, orig_dev);
- pt_prev = NULL;
+ if (*pt_prev) {
+ ret = deliver_skb(skb, *pt_prev, orig_dev);
+ *pt_prev = NULL;
}
switch (rx_handler(&skb)) {
case RX_HANDLER_CONSUMED:
@@ -4181,47 +4182,112 @@ ncls:
/* deliver only exact match when indicated */
if (likely(!deliver_exact)) {
- deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
+ deliver_ptype_list_skb(skb, pt_prev, orig_dev, type,
&ptype_base[ntohs(type) &
PTYPE_HASH_MASK]);
}
- deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
+ deliver_ptype_list_skb(skb, pt_prev, orig_dev, type,
&orig_dev->ptype_specific);
if (unlikely(skb->dev != orig_dev)) {
- deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
+ deliver_ptype_list_skb(skb, pt_prev, orig_dev, type,
&skb->dev->ptype_specific);
}
-
- if (pt_prev) {
- if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
- goto drop;
- else
- ret = pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
- } else {
+ if (*pt_prev && unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
+ goto drop;
+ return ret;
drop:
- if (!deliver_exact)
- atomic_long_inc(&skb->dev->rx_dropped);
- else
- atomic_long_inc(&skb->dev->rx_nohandler);
- kfree_skb(skb);
- /* Jamal, now you will not able to escape explaining
- * me how you were going to use this. :-)
- */
- ret = NET_RX_DROP;
- }
-
+ if (!deliver_exact)
+ atomic_long_inc(&skb->dev->rx_dropped);
+ else
+ atomic_long_inc(&skb->dev->rx_nohandler);
+ kfree_skb(skb);
+ /* Jamal, now you will not able to escape explaining
+ * me how you were going to use this. :-)
+ */
+ ret = NET_RX_DROP;
out:
+ *pt_prev = NULL;
return ret;
}
-static void __netif_receive_skb_list_core(struct sk_buff_head *list, bool pfmemalloc)
+static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
+{
+ struct net_device *orig_dev = skb->dev;
+ struct packet_type *pt_prev;
+ int ret;
+
+ ret = __netif_receive_skb_taps(skb, pfmemalloc, &pt_prev);
+ if (pt_prev)
+ ret = pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
+ return ret;
+}
+
+static inline void __netif_receive_skb_list_ptype(struct sk_buff_head *list,
+ struct packet_type *pt_prev,
+ struct net_device *orig_dev)
{
struct sk_buff *skb;
while ((skb = __skb_dequeue(list)) != NULL)
- __netif_receive_skb_core(skb, pfmemalloc);
+ pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
+}
+
+static void __netif_receive_skb_list_core(struct sk_buff_head *list, 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. Unless, that is, a ptype can
+ * be delivered to more than once for a single packet - but that seems
+ * like it would be a bad idea anyway.
+ * So it should be fine (at least, I think so), but you'll lose the
+ * (putative) performance benefits of batching.
+ */
+ /* Current (common) ptype of sublist */
+ struct packet_type *pt_curr = NULL;
+ /* In the normal (device RX) case, orig_dev should be the same for
+ * every skb in the list. But as I'm not certain of this, I check
+ * it's constant and split the list if not.
+ * So, od_curr is the current (common) orig_dev of sublist.
+ */
+ struct net_device *od_curr = NULL;
+ struct sk_buff_head sublist;
+ struct sk_buff *skb;
+
+ __skb_queue_head_init(&sublist);
+
+ while ((skb = __skb_dequeue(list)) != NULL) {
+ struct packet_type *pt_prev;
+ struct net_device *orig_dev = skb->dev;
+
+ __netif_receive_skb_taps(skb, pfmemalloc, &pt_prev);
+ if (pt_prev) {
+ if (skb_queue_empty(&sublist)) {
+ pt_curr = pt_prev;
+ od_curr = orig_dev;
+ } else if (!(pt_curr == pt_prev &&
+ od_curr == orig_dev)) {
+ /* dispatch old sublist */
+ __netif_receive_skb_list_ptype(&sublist,
+ pt_curr,
+ od_curr);
+ /* start new sublist */
+ __skb_queue_head_init(&sublist);
+ pt_curr = pt_prev;
+ od_curr = orig_dev;
+ }
+ __skb_queue_tail(&sublist, skb);
+ }
+ }
+
+ /* dispatch final sublist */
+ __netif_receive_skb_list_ptype(&sublist, pt_curr, od_curr);
}
static int __netif_receive_skb(struct sk_buff *skb)
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