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authorEric Dumazet <edumazet@google.com>2013-12-05 04:45:08 -0800
committerDavid S. Miller <davem@davemloft.net>2013-12-06 15:24:02 -0500
commite6247027e5173c00efb2084d688d06ff835bc3b0 (patch)
tree44c1fc4da5358f778fc82a1056ef9a2a6e7eea0e /net/core/dev.c
parentf96eb74c84ebb09a03031f7f1e51789a928f9de0 (diff)
downloadlinux-linaro-stable-e6247027e5173c00efb2084d688d06ff835bc3b0.tar.gz
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>
Diffstat (limited to 'net/core/dev.c')
-rw-r--r--net/core/dev.c45
1 files changed, 30 insertions, 15 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index c98052487e98..6cc98dd49c7a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2145,30 +2145,42 @@ void __netif_schedule(struct Qdisc *q)
}
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)
+{
+ return (struct dev_kfree_skb_cb *)skb->cb;
+}
+
+void __dev_kfree_skb_irq(struct sk_buff *skb, enum skb_free_reason reason)
{
- if (atomic_dec_and_test(&skb->users)) {
- struct softnet_data *sd;
- unsigned long flags;
+ 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);
+ 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);
+EXPORT_SYMBOL(__dev_kfree_skb_irq);
-void dev_kfree_skb_any(struct sk_buff *skb)
+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 @@ static void net_tx_action(struct softirq_action *h)
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);
}
}