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authorCong Wang <xiyou.wangcong@gmail.com>2013-01-21 00:39:24 +0000
committerDavid S. Miller <davem@davemloft.net>2013-01-21 14:26:17 -0500
commit441d9d327f1e770f5aa76fd91735851ac6e1e236 (patch)
treef7a0a8d206d5745fd196bc9a5c98c2f8d67086ac /net/core/flow_dissector.c
parentcd5f20461de8e3e9b04932e4ba3e37afe39b8898 (diff)
net: move rx and tx hash functions to net/core/flow_dissector.c
__skb_tx_hash() and __skb_get_rxhash() are all for calculating hash value based by some fields in skb, mostly used for selecting queues by device drivers. Meanwhile, net/core/dev.c is bloating. Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/flow_dissector.c')
-rw-r--r--net/core/flow_dissector.c173
1 files changed, 173 insertions, 0 deletions
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 466820b6e344..9d4c7201400d 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -143,3 +143,176 @@ ipv6:
return true;
}
EXPORT_SYMBOL(skb_flow_dissect);
+
+static u32 hashrnd __read_mostly;
+
+/*
+ * __skb_get_rxhash: calculate a flow hash based on src/dst addresses
+ * and src/dst port numbers. Sets rxhash in skb to non-zero hash value
+ * on success, zero indicates no valid hash. Also, sets l4_rxhash in skb
+ * if hash is a canonical 4-tuple hash over transport ports.
+ */
+void __skb_get_rxhash(struct sk_buff *skb)
+{
+ struct flow_keys keys;
+ u32 hash;
+
+ if (!skb_flow_dissect(skb, &keys))
+ return;
+
+ if (keys.ports)
+ skb->l4_rxhash = 1;
+
+ /* get a consistent hash (same value on both flow directions) */
+ if (((__force u32)keys.dst < (__force u32)keys.src) ||
+ (((__force u32)keys.dst == (__force u32)keys.src) &&
+ ((__force u16)keys.port16[1] < (__force u16)keys.port16[0]))) {
+ swap(keys.dst, keys.src);
+ swap(keys.port16[0], keys.port16[1]);
+ }
+
+ hash = jhash_3words((__force u32)keys.dst,
+ (__force u32)keys.src,
+ (__force u32)keys.ports, hashrnd);
+ if (!hash)
+ hash = 1;
+
+ skb->rxhash = hash;
+}
+EXPORT_SYMBOL(__skb_get_rxhash);
+
+/*
+ * Returns a Tx hash based on the given packet descriptor a Tx queues' number
+ * to be used as a distribution range.
+ */
+u16 __skb_tx_hash(const struct net_device *dev, const struct sk_buff *skb,
+ unsigned int num_tx_queues)
+{
+ u32 hash;
+ u16 qoffset = 0;
+ u16 qcount = num_tx_queues;
+
+ if (skb_rx_queue_recorded(skb)) {
+ hash = skb_get_rx_queue(skb);
+ while (unlikely(hash >= num_tx_queues))
+ hash -= num_tx_queues;
+ return hash;
+ }
+
+ if (dev->num_tc) {
+ u8 tc = netdev_get_prio_tc_map(dev, skb->priority);
+ qoffset = dev->tc_to_txq[tc].offset;
+ qcount = dev->tc_to_txq[tc].count;
+ }
+
+ if (skb->sk && skb->sk->sk_hash)
+ hash = skb->sk->sk_hash;
+ else
+ hash = (__force u16) skb->protocol;
+ hash = jhash_1word(hash, hashrnd);
+
+ return (u16) (((u64) hash * qcount) >> 32) + qoffset;
+}
+EXPORT_SYMBOL(__skb_tx_hash);
+
+static inline u16 dev_cap_txqueue(struct net_device *dev, u16 queue_index)
+{
+ if (unlikely(queue_index >= dev->real_num_tx_queues)) {
+ net_warn_ratelimited("%s selects TX queue %d, but real number of TX queues is %d\n",
+ dev->name, queue_index,
+ dev->real_num_tx_queues);
+ return 0;
+ }
+ return queue_index;
+}
+
+static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb)
+{
+#ifdef CONFIG_XPS
+ struct xps_dev_maps *dev_maps;
+ struct xps_map *map;
+ int queue_index = -1;
+
+ rcu_read_lock();
+ dev_maps = rcu_dereference(dev->xps_maps);
+ if (dev_maps) {
+ map = rcu_dereference(
+ dev_maps->cpu_map[raw_smp_processor_id()]);
+ if (map) {
+ if (map->len == 1)
+ queue_index = map->queues[0];
+ else {
+ u32 hash;
+ if (skb->sk && skb->sk->sk_hash)
+ hash = skb->sk->sk_hash;
+ else
+ hash = (__force u16) skb->protocol ^
+ skb->rxhash;
+ hash = jhash_1word(hash, hashrnd);
+ queue_index = map->queues[
+ ((u64)hash * map->len) >> 32];
+ }
+ if (unlikely(queue_index >= dev->real_num_tx_queues))
+ queue_index = -1;
+ }
+ }
+ rcu_read_unlock();
+
+ return queue_index;
+#else
+ return -1;
+#endif
+}
+
+u16 __netdev_pick_tx(struct net_device *dev, struct sk_buff *skb)
+{
+ struct sock *sk = skb->sk;
+ int queue_index = sk_tx_queue_get(sk);
+
+ if (queue_index < 0 || skb->ooo_okay ||
+ queue_index >= dev->real_num_tx_queues) {
+ int new_index = get_xps_queue(dev, skb);
+ if (new_index < 0)
+ new_index = skb_tx_hash(dev, skb);
+
+ if (queue_index != new_index && sk) {
+ struct dst_entry *dst =
+ rcu_dereference_check(sk->sk_dst_cache, 1);
+
+ if (dst && skb_dst(skb) == dst)
+ sk_tx_queue_set(sk, queue_index);
+
+ }
+
+ queue_index = new_index;
+ }
+
+ return queue_index;
+}
+EXPORT_SYMBOL(__netdev_pick_tx);
+
+struct netdev_queue *netdev_pick_tx(struct net_device *dev,
+ struct sk_buff *skb)
+{
+ int queue_index = 0;
+
+ if (dev->real_num_tx_queues != 1) {
+ const struct net_device_ops *ops = dev->netdev_ops;
+ if (ops->ndo_select_queue)
+ queue_index = ops->ndo_select_queue(dev, skb);
+ else
+ queue_index = __netdev_pick_tx(dev, skb);
+ queue_index = dev_cap_txqueue(dev, queue_index);
+ }
+
+ skb_set_queue_mapping(skb, queue_index);
+ return netdev_get_tx_queue(dev, queue_index);
+}
+
+static int __init initialize_hashrnd(void)
+{
+ get_random_bytes(&hashrnd, sizeof(hashrnd));
+ return 0;
+}
+
+late_initcall_sync(initialize_hashrnd);