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| author | Cong Wang <xiyou.wangcong@gmail.com> | 2017-09-12 01:33:30 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-09-13 05:41:02 +0200 |
| commit | d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da (patch) | |
| tree | 06503aa2783d3a75739ec13263b1644779316274 /net | |
| parent | tcp/dccp: remove reqsk_put() from inet_child_forget() (diff) | |
| download | linux-d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da.tar.xz linux-d7fb60b9cafb982cb2e46a267646a8dfd4f2e5da.zip | |
net_sched: get rid of tcfa_rcu
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().
Please see also the comments in code.
Cc: Jiri Pirko <jiri@mellanox.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/sched/act_api.c | 17 |
1 files changed, 8 insertions, 9 deletions
diff --git a/net/sched/act_api.c b/net/sched/act_api.c index a306974e2fb4..fcd7dc7b807a 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -53,10 +53,13 @@ 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) +/* XXX: For standalone actions, we don't need a RCU grace period either, because + * actions are always connected to filters and filters are already destroyed in + * RCU callbacks, so after a RCU grace period actions are already disconnected + * from filters. Readers later can not find us. + */ +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 +79,7 @@ static void tcf_idr_remove(struct tcf_idrinfo *idrinfo, struct tc_action *p) idr_remove_ext(&idrinfo->action_idr, p->tcfa_index); spin_unlock_bh(&idrinfo->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_idr_release(struct tc_action *p, bool bind, bool strict) @@ -259,7 +258,7 @@ void tcf_idr_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_idr_cleanup); |