diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index ada02c4a4f51..22179b2fda72 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -1302,7 +1302,7 @@ struct mini_Qdisc { struct tcf_block *block; struct gnet_stats_basic_sync __percpu *cpu_bstats; struct gnet_stats_queue __percpu *cpu_qstats; - struct rcu_head rcu; + unsigned long rcu_state; }; static inline void mini_qdisc_bstats_cpu_update(struct mini_Qdisc *miniq, diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index b0ff0dff2773..24899efc51be 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -1487,10 +1487,6 @@ void psched_ppscfg_precompute(struct psched_pktrate *r, u64 pktrate64) } EXPORT_SYMBOL(psched_ppscfg_precompute); -static void mini_qdisc_rcu_func(struct rcu_head *head) -{ -} - void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp, struct tcf_proto *tp_head) { @@ -1503,28 +1499,30 @@ void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp, if (!tp_head) { RCU_INIT_POINTER(*miniqp->p_miniq, NULL); - /* Wait for flying RCU callback before it is freed. */ - rcu_barrier(); - return; + } else { + miniq = !miniq_old || miniq_old == &miniqp->miniq2 ? + &miniqp->miniq1 : &miniqp->miniq2; + + /* We need to make sure that readers won't see the miniq + * we are about to modify. So ensure that at least one RCU + * grace period has elapsed since the miniq was made + * inactive. + */ + if (IS_ENABLED(CONFIG_PREEMPT_RT)) + cond_synchronize_rcu(miniq->rcu_state); + else if (!poll_state_synchronize_rcu(miniq->rcu_state)) + synchronize_rcu_expedited(); + + miniq->filter_list = tp_head; + rcu_assign_pointer(*miniqp->p_miniq, miniq); } - miniq = !miniq_old || miniq_old == &miniqp->miniq2 ? - &miniqp->miniq1 : &miniqp->miniq2; - - /* We need to make sure that readers won't see the miniq - * we are about to modify. So wait until previous call_rcu callback - * is done. - */ - rcu_barrier(); - miniq->filter_list = tp_head; - rcu_assign_pointer(*miniqp->p_miniq, miniq); - if (miniq_old) - /* This is counterpart of the rcu barriers above. We need to + /* This is counterpart of the rcu sync above. We need to * block potential new user of miniq_old until all readers * are not seeing it. */ - call_rcu(&miniq_old->rcu, mini_qdisc_rcu_func); + miniq_old->rcu_state = start_poll_synchronize_rcu(); } EXPORT_SYMBOL(mini_qdisc_pair_swap); @@ -1543,6 +1541,8 @@ void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc, miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats; miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats; miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats; + miniqp->miniq1.rcu_state = get_state_synchronize_rcu(); + miniqp->miniq2.rcu_state = miniqp->miniq1.rcu_state; miniqp->p_miniq = p_miniq; } EXPORT_SYMBOL(mini_qdisc_pair_init);