diff options
| -rw-r--r-- | net/core/dev.c | 51 |
1 files changed, 47 insertions, 4 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 03624192862a..6089ac9d17ba 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5621,17 +5621,60 @@ static void flush_backlog(struct work_struct *work) 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) - queue_work_on(cpu, system_highpri_wq, - per_cpu_ptr(&flush_works, 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(); |