net_sched: introduce tcf_exts_get_net() and tcf_exts_put_net() (e4b95c41) · Commits · 戴 / test

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>

include/net/pkt_cls.h

+24 −0

Original line number	Diff line number	Diff line
		@@ -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)
		{

net/sched/cls_api.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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]) \|\|

Admin message