net: try to avoid unneeded backlog flush

	local_bh_enable();

}

static bool flush_required(int cpu)

{

#if IS_ENABLED(CONFIG_RPS)

	struct softnet_data *sd = &per_cpu(softnet_data, cpu);

	bool do_flush;

	local_irq_disable();

	rps_lock(sd);

	/* as insertion into process_queue happens with the rps lock held,

	 * process_queue access may race only with dequeue

	 */

	do_flush = !skb_queue_empty(&sd->input_pkt_queue) ||

		   !skb_queue_empty_lockless(&sd->process_queue);

	rps_unlock(sd);

	local_irq_enable();

	return do_flush;

#endif

	/* without RPS we can't safely check input_pkt_queue: during a

	 * concurrent remote skb_queue_splice() we can detect as empty both

	 * input_pkt_queue and process_queue even if the latter could end-up

	 * containing a lot of packets.

	 */

	return true;

}

static void flush_all_backlogs(void)

{

	static cpumask_t flush_cpus;

	unsigned int cpu;

	/* since we are under rtnl lock protection we can use static data

	 * for the cpumask and avoid allocating on stack the possibly

	 * large mask

	 */

	ASSERT_RTNL();

	get_online_cpus();

	for_each_online_cpu(cpu)

	cpumask_clear(&flush_cpus);

	for_each_online_cpu(cpu) {

		if (flush_required(cpu)) {

			queue_work_on(cpu, system_highpri_wq,

				      per_cpu_ptr(&flush_works, cpu));

			cpumask_set_cpu(cpu, &flush_cpus);

		}

	}

	for_each_online_cpu(cpu)

	/* we can have in flight packet[s] on the cpus we are not flushing,

	 * synchronize_net() in rollback_registered_many() will take care of

	 * them

	 */

	for_each_cpu(cpu, &flush_cpus)

		flush_work(per_cpu_ptr(&flush_works, cpu));

	put_online_cpus();