/**
* This function is both preempt and irq safe. The former is due to explicit
* preemption disable. The latter is guaranteed by the fact that the slow path
* is explicitly protected by an irq-safe spinlock whereas the fast patch uses
* this_cpu_add which is irq-safe by definition. Hence there is no need muck
* with irq state before calling this one
*/
void percpu_counter_add_batch(struct percpu_counter *fbc, int64_t amount,
int32_t batch)
{
int64_t count;
preempt_disable();
count = __this_cpu_read(*fbc->counters) + amount;
if (count >= batch || count <= -batch) {
unsigned long flags;
spin_lock_irqsave(&fbc->lock);
fbc->count += count;
__this_cpu_sub(*fbc->counters, count - amount);
spin_unlock_irqsave(&fbc->lock);
} else {
this_cpu_add(*fbc->counters, amount);
}
preempt_enable();
}
static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
struct sk_buff **to_free)
{
int band = prio2band[skb->priority & TC_PRIO_MAX];
struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
struct skb_array *q = band2list(priv, band);
unsigned int pkt_len = qdisc_pkt_len(skb);
int err;
err = skb_array_produce(q, skb);
if (unlikely(err))
return qdisc_drop_cpu(skb, qdisc, to_free);
qdisc_qstats_cpu_qlen_inc(qdisc);
/* Note: skb can not be used after skb_array_produce(),
* so we better not use qdisc_qstats_cpu_backlog_inc()
*/
this_cpu_add(qdisc->cpu_qstats->backlog, pkt_len);
return NET_XMIT_SUCCESS;
}
