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| author |   Cong Wang <xiyou.wangcong@gmail.com> | 2017-11-06 13:47:19 -0800 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2017-11-09 10:03:09 +0900 |
| commit | e4b95c41df36befcfd117210900cd790bc2cd048 (patch) | |
| tree | 53d51109b9ec8ebc29f14fc9689671cda519556a | |
| parent | Revert "net_sched: hold netns refcnt for each action" (diff) | |
| download | linux-dev-e4b95c41df36befcfd117210900cd790bc2cd048.tar.xz linux-dev-e4b95c41df36befcfd117210900cd790bc2cd048.zip | |
net_sched: introduce tcf_exts_get_net() and tcf_exts_put_net()
Instead of holding netns refcnt in tc actions, we can minimize
the holding time by saving it in struct tcf_exts instead. This
means we can just hold netns refcnt right before call_rcu() and
release it after tcf_exts_destroy() is done.
However, because on netns cleanup path we call tcf_proto_destroy()
too, obviously we can not hold netns for a zero refcnt, in this
case we have to do cleanup synchronously. It is fine for RCU too,
the caller cleanup_net() already waits for a grace period.
For other cases, refcnt is non-zero and we can safely grab it as
normal and release it after we are done.
This patch provides two new API for each filter to use:
tcf_exts_get_net() and tcf_exts_put_net(). And all filters now can
use the following pattern:
void __destroy_filter() {
tcf_exts_destroy();
tcf_exts_put_net(); // <== release netns refcnt
kfree();
}
void some_work() {
rtnl_lock();
__destroy_filter();
rtnl_unlock();
}
void some_rcu_callback() {
tcf_queue_work(some_work);
}
if (tcf_exts_get_net()) // <== hold netns refcnt
call_rcu(some_rcu_callback);
else
__destroy_filter();
Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/net/pkt_cls.h | 24 | ||||
| -rw-r--r-- | net/sched/cls_api.c | 1 |
2 files changed, 25 insertions, 0 deletions
diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h index 70ca2437740e..8826747ef83e 100644 --- a/include/net/pkt_cls.h +++ b/include/net/pkt_cls.h @@ -94,6 +94,7 @@ struct tcf_exts { __u32 type; /* for backward compat(TCA_OLD_COMPAT) */ int nr_actions; struct tc_action **actions; + struct net *net; #endif /* Map to export classifier specific extension TLV types to the * generic extensions API. Unsupported extensions must be set to 0. @@ -107,6 +108,7 @@ static inline int tcf_exts_init(struct tcf_exts *exts, int action, int police) #ifdef CONFIG_NET_CLS_ACT exts->type = 0; exts->nr_actions = 0; + exts->net = NULL; exts->actions = kcalloc(TCA_ACT_MAX_PRIO, sizeof(struct tc_action *), GFP_KERNEL); if (!exts->actions) @@ -117,6 +119,28 @@ static inline int tcf_exts_init(struct tcf_exts *exts, int action, int police) return 0; } +/* Return false if the netns is being destroyed in cleanup_net(). Callers + * need to do cleanup synchronously in this case, otherwise may race with + * tc_action_net_exit(). Return true for other cases. + */ +static inline bool tcf_exts_get_net(struct tcf_exts *exts) +{ +#ifdef CONFIG_NET_CLS_ACT + exts->net = maybe_get_net(exts->net); + return exts->net != NULL; +#else + return true; +#endif +} + +static inline void tcf_exts_put_net(struct tcf_exts *exts) +{ +#ifdef CONFIG_NET_CLS_ACT + if (exts->net) + put_net(exts->net); +#endif +} + static inline void tcf_exts_to_list(const struct tcf_exts *exts, struct list_head *actions) { diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index b2d310745487..ecbb019efcbd 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -927,6 +927,7 @@ int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr **tb, exts->actions[i++] = act; exts->nr_actions = i; } + exts->net = net; } #else if ((exts->action && tb[exts->action]) || |