[Patch net v2 1/2] net_sched: get rid of tcfa_rcu
From: Cong Wang <hidden>
Date: 2017-09-07 04:26:17
Subsystem:
networking [general], tc subsystem, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Jamal Hadi Salim, Jiri Pirko, Linus Torvalds
gen estimator has been rewritten in commit 1c0d32fde5bd
("net_sched: gen_estimator: complete rewrite of rate estimators"),
the caller is no longer needed to wait for a grace period.
So this patch gets rid of it.
This also completely closes a race condition between action free
path and filter chain add/remove path for the following patch.
Because otherwise the nested RCU callback can't be caught by
rcu_barrier().
Cc: Jiri Pirko <redacted>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Cong Wang <redacted>
---
include/net/act_api.h | 2 --
net/sched/act_api.c | 12 +++---------
2 files changed, 3 insertions(+), 11 deletions(-)
diff --git a/include/net/act_api.h b/include/net/act_api.h
index 26ffd8333f50..68218a5f8e72 100644
--- a/include/net/act_api.h
+++ b/include/net/act_api.h@@ -38,7 +38,6 @@ struct tc_action { struct gnet_stats_queue tcfa_qstats; struct net_rate_estimator __rcu *tcfa_rate_est; spinlock_t tcfa_lock; - struct rcu_head tcfa_rcu; struct gnet_stats_basic_cpu __percpu *cpu_bstats; struct gnet_stats_queue __percpu *cpu_qstats; struct tc_cookie *act_cookie;
@@ -55,7 +54,6 @@ struct tc_action { #define tcf_qstats common.tcfa_qstats #define tcf_rate_est common.tcfa_rate_est #define tcf_lock common.tcfa_lock -#define tcf_rcu common.tcfa_rcu static inline unsigned int tcf_hash(u32 index, unsigned int hmask) {
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index f2e9ed34a963..fc17d286a6a2 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c@@ -53,10 +53,8 @@ static void tcf_action_goto_chain_exec(const struct tc_action *a, res->goto_tp = rcu_dereference_bh(chain->filter_chain); } -static void free_tcf(struct rcu_head *head) +static void free_tcf(struct tc_action *p) { - struct tc_action *p = container_of(head, struct tc_action, tcfa_rcu); - free_percpu(p->cpu_bstats); free_percpu(p->cpu_qstats);
@@ -76,11 +74,7 @@ static void tcf_hash_destroy(struct tcf_hashinfo *hinfo, struct tc_action *p) hlist_del(&p->tcfa_head); spin_unlock_bh(&hinfo->lock); gen_kill_estimator(&p->tcfa_rate_est); - /* - * gen_estimator est_timer() might access p->tcfa_lock - * or bstats, wait a RCU grace period before freeing p - */ - call_rcu(&p->tcfa_rcu, free_tcf); + free_tcf(p); } int __tcf_hash_release(struct tc_action *p, bool bind, bool strict)
@@ -271,7 +265,7 @@ void tcf_hash_cleanup(struct tc_action *a, struct nlattr *est) { if (est) gen_kill_estimator(&a->tcfa_rate_est); - call_rcu(&a->tcfa_rcu, free_tcf); + free_tcf(a); } EXPORT_SYMBOL(tcf_hash_cleanup);
--
2.13.0