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net: core: introduce mini_Qdisc and eliminate usage of tp->q for clsact fastpath

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In sch_handle_egress and sch_handle_ingress tp->q is used only in order
to update stats. So stats and filter list are the only things that are
needed in clsact qdisc fastpath processing. Introduce new mini_Qdisc
struct to hold those items. Also, introduce a helper to swap the
mini_Qdisc structures in case filter list head changes.

This removes need for tp->q usage without added overhead.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jiri Pirko
2017-11-03 11:46:25 +01:00
committed by David S. Miller
parent c7eb7d7230
commit 46209401f8
5 changed files with 109 additions and 18 deletions
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46
net/sched/sch_generic.c
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@@ -1024,3 +1024,49 @@ void psched_ratecfg_precompute(struct psched_ratecfg *r,
}
}
EXPORT_SYMBOL(psched_ratecfg_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)
{
struct mini_Qdisc *miniq_old = rtnl_dereference(*miniqp->p_miniq);
struct mini_Qdisc *miniq;
if (!tp_head) {
RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
return;
}
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_bh callback
* is done.
*/
rcu_barrier_bh();
miniq->filter_list = tp_head;
rcu_assign_pointer(*miniqp->p_miniq, miniq);
if (miniq_old)
/* This is counterpart of the rcu barrier above. We need to
* block potential new user of miniq_old until all readers
* are not seeing it.
*/
call_rcu_bh(&miniq_old->rcu, mini_qdisc_rcu_func);
}
EXPORT_SYMBOL(mini_qdisc_pair_swap);
void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
struct mini_Qdisc __rcu **p_miniq)
{
miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
miniqp->p_miniq = p_miniq;
}
EXPORT_SYMBOL(mini_qdisc_pair_init);