rps: keep the old behavior on SMP without rps
keep the old behavior on SMP without rps
RPS introduces a lock operation to per cpu variable input_pkt_queue on
SMP whenever rps is enabled or not. On SMP without RPS, this lock isn't
needed at all.
Signed-off-by: Changli Gao <xiaosuo@gmail.com>
----
net/core/dev.c | 42 ++++++++++++++++++++++++++++--------------
1 file changed, 28 insertions(+), 14 deletions(-)
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index 887aa84..427cd53 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -206,6 +206,20 @@
return &net->dev_index_head[ifindex & (NETDEV_HASHENTRIES - 1)];
}
+static inline void rps_lock(struct softnet_data *queue)
+{
+#ifdef CONFIG_RPS
+ spin_lock(&queue->input_pkt_queue.lock);
+#endif
+}
+
+static inline void rps_unlock(struct softnet_data *queue)
+{
+#ifdef CONFIG_RPS
+ spin_unlock(&queue->input_pkt_queue.lock);
+#endif
+}
+
/* Device list insertion */
static int list_netdevice(struct net_device *dev)
{
@@ -2313,13 +2327,13 @@
local_irq_save(flags);
__get_cpu_var(netdev_rx_stat).total++;
- spin_lock(&queue->input_pkt_queue.lock);
+ rps_lock(queue);
if (queue->input_pkt_queue.qlen <= netdev_max_backlog) {
if (queue->input_pkt_queue.qlen) {
enqueue:
__skb_queue_tail(&queue->input_pkt_queue, skb);
- spin_unlock_irqrestore(&queue->input_pkt_queue.lock,
- flags);
+ rps_unlock(queue);
+ local_irq_restore(flags);
return NET_RX_SUCCESS;
}
@@ -2341,7 +2355,7 @@
goto enqueue;
}
- spin_unlock(&queue->input_pkt_queue.lock);
+ rps_unlock(queue);
__get_cpu_var(netdev_rx_stat).dropped++;
local_irq_restore(flags);
@@ -2766,19 +2780,19 @@
EXPORT_SYMBOL(netif_receive_skb);
/* Network device is going away, flush any packets still pending */
-static void flush_backlog(struct net_device *dev, int cpu)
+static void flush_backlog(void *arg)
{
- struct softnet_data *queue = &per_cpu(softnet_data, cpu);
+ struct net_device *dev = arg;
+ struct softnet_data *queue = &__get_cpu_var(softnet_data);
struct sk_buff *skb, *tmp;
- unsigned long flags;
- spin_lock_irqsave(&queue->input_pkt_queue.lock, flags);
+ rps_lock(queue);
skb_queue_walk_safe(&queue->input_pkt_queue, skb, tmp)
if (skb->dev == dev) {
__skb_unlink(skb, &queue->input_pkt_queue);
kfree_skb(skb);
}
- spin_unlock_irqrestore(&queue->input_pkt_queue.lock, flags);
+ rps_unlock(queue);
}
static int napi_gro_complete(struct sk_buff *skb)
@@ -3091,14 +3105,16 @@
do {
struct sk_buff *skb;
- spin_lock_irq(&queue->input_pkt_queue.lock);
+ local_irq_disable();
+ rps_lock(queue);
skb = __skb_dequeue(&queue->input_pkt_queue);
if (!skb) {
__napi_complete(napi);
spin_unlock_irq(&queue->input_pkt_queue.lock);
break;
}
- spin_unlock_irq(&queue->input_pkt_queue.lock);
+ rps_unlock(queue);
+ local_irq_enable();
__netif_receive_skb(skb);
} while (++work < quota && jiffies == start_time);
@@ -5548,7 +5564,6 @@
while (!list_empty(&list)) {
struct net_device *dev
= list_first_entry(&list, struct net_device, todo_list);
- int i;
list_del(&dev->todo_list);
if (unlikely(dev->reg_state != NETREG_UNREGISTERING)) {
@@ -5560,8 +5575,7 @@
dev->reg_state = NETREG_UNREGISTERED;
- for_each_online_cpu(i)
- flush_backlog(dev, i);
+ on_each_cpu(flush_backlog, dev, 1);
netdev_wait_allrefs(dev);