net: introduce dev_consume_skb_any()
Some network drivers use dev_kfree_skb_any() and dev_kfree_skb_irq()
helpers to free skbs, both for dropped packets and TX completed ones.
We need to separate the two causes to get better diagnostics
given by dropwatch or "perf record -e skb:kfree_skb"
This patch provides two new helpers, dev_consume_skb_any() and
dev_consume_skb_irq() to be used for consumed skbs.
__dev_kfree_skb_irq() is slightly optimized to remove one
atomic_dec_and_test() in fast path, and use this_cpu_{r|w} accessors.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index c980524..6cc98dd 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2145,30 +2145,42 @@
}
EXPORT_SYMBOL(__netif_schedule);
-void dev_kfree_skb_irq(struct sk_buff *skb)
+struct dev_kfree_skb_cb {
+ enum skb_free_reason reason;
+};
+
+static struct dev_kfree_skb_cb *get_kfree_skb_cb(const struct sk_buff *skb)
{
- if (atomic_dec_and_test(&skb->users)) {
- struct softnet_data *sd;
- unsigned long flags;
-
- local_irq_save(flags);
- sd = &__get_cpu_var(softnet_data);
- skb->next = sd->completion_queue;
- sd->completion_queue = skb;
- raise_softirq_irqoff(NET_TX_SOFTIRQ);
- local_irq_restore(flags);
- }
+ return (struct dev_kfree_skb_cb *)skb->cb;
}
-EXPORT_SYMBOL(dev_kfree_skb_irq);
-void dev_kfree_skb_any(struct sk_buff *skb)
+void __dev_kfree_skb_irq(struct sk_buff *skb, enum skb_free_reason reason)
+{
+ unsigned long flags;
+
+ if (likely(atomic_read(&skb->users) == 1)) {
+ smp_rmb();
+ atomic_set(&skb->users, 0);
+ } else if (likely(!atomic_dec_and_test(&skb->users))) {
+ return;
+ }
+ get_kfree_skb_cb(skb)->reason = reason;
+ local_irq_save(flags);
+ skb->next = __this_cpu_read(softnet_data.completion_queue);
+ __this_cpu_write(softnet_data.completion_queue, skb);
+ raise_softirq_irqoff(NET_TX_SOFTIRQ);
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL(__dev_kfree_skb_irq);
+
+void __dev_kfree_skb_any(struct sk_buff *skb, enum skb_free_reason reason)
{
if (in_irq() || irqs_disabled())
- dev_kfree_skb_irq(skb);
+ __dev_kfree_skb_irq(skb, reason);
else
dev_kfree_skb(skb);
}
-EXPORT_SYMBOL(dev_kfree_skb_any);
+EXPORT_SYMBOL(__dev_kfree_skb_any);
/**
@@ -3306,7 +3318,10 @@
clist = clist->next;
WARN_ON(atomic_read(&skb->users));
- trace_kfree_skb(skb, net_tx_action);
+ if (likely(get_kfree_skb_cb(skb)->reason == SKB_REASON_CONSUMED))
+ trace_consume_skb(skb);
+ else
+ trace_kfree_skb(skb, net_tx_action);
__kfree_skb(skb);
}
}