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Commit 25d8c0d5 authored by John Fastabend's avatar John Fastabend Committed by David S. Miller
Browse files

net: rcu-ify tcf_proto 



rcu'ify tcf_proto this allows calling tc_classify() without holding
any locks. Updaters are protected by RTNL.

This patch prepares the core net_sched infrastracture for running
the classifier/action chains without holding the qdisc lock however
it does nothing to ensure cls_xxx and act_xxx types also work without
locking. Additional patches are required to address the fall out.

Signed-off-by: default avatarJohn Fastabend <john.r.fastabend@intel.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 46e5da40

include/net/sch_generic.h

+5 −4
Original line number Diff line number Diff line
@@ -143,7 +143,7 @@ struct Qdisc_class_ops { 
	void			(*walk)(struct Qdisc *, struct qdisc_walker * arg);



	/* Filter manipulation */

	struct tcf_proto **	(*tcf_chain)(struct Qdisc *, unsigned long);

	struct tcf_proto __rcu ** (*tcf_chain)(struct Qdisc *, unsigned long);

	unsigned long		(*bind_tcf)(struct Qdisc *, unsigned long,

					u32 classid);

	void			(*unbind_tcf)(struct Qdisc *, unsigned long);
@@ -212,8 +212,8 @@ struct tcf_proto_ops { 


struct tcf_proto {

	/* Fast access part */

	struct tcf_proto	*next;

	void			*root;

	struct tcf_proto __rcu	*next;

	void __rcu		*root;

	int			(*classify)(struct sk_buff *,

					    const struct tcf_proto *,

					    struct tcf_result *);
@@ -225,6 +225,7 @@ struct tcf_proto { 
	struct Qdisc		*q;

	void			*data;

	const struct tcf_proto_ops	*ops;

	struct rcu_head		rcu;

};



struct qdisc_skb_cb {
@@ -378,7 +379,7 @@ struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue, 
void __qdisc_calculate_pkt_len(struct sk_buff *skb,

			       const struct qdisc_size_table *stab);

void tcf_destroy(struct tcf_proto *tp);

void tcf_destroy_chain(struct tcf_proto **fl);

void tcf_destroy_chain(struct tcf_proto __rcu **fl);



/* Reset all TX qdiscs greater then index of a device.  */

static inline void qdisc_reset_all_tx_gt(struct net_device *dev, unsigned int i)

net/sched/cls_api.c

+15 −15
Original line number Diff line number Diff line
@@ -117,7 +117,6 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n) 
{

	struct net *net = sock_net(skb->sk);

	struct nlattr *tca[TCA_MAX + 1];

	spinlock_t *root_lock;

	struct tcmsg *t;

	u32 protocol;

	u32 prio;
@@ -125,7 +124,8 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n) 
	u32 parent;

	struct net_device *dev;

	struct Qdisc  *q;

	struct tcf_proto **back, **chain;

	struct tcf_proto __rcu **back;

	struct tcf_proto __rcu **chain;

	struct tcf_proto *tp;

	const struct tcf_proto_ops *tp_ops;

	const struct Qdisc_class_ops *cops;
@@ -197,7 +197,9 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n) 
		goto errout;



	/* Check the chain for existence of proto-tcf with this priority */

	for (back = chain; (tp = *back) != NULL; back = &tp->next) {

	for (back = chain;

	     (tp = rtnl_dereference(*back)) != NULL;

	     back = &tp->next) {

		if (tp->prio >= prio) {

			if (tp->prio == prio) {

				if (!nprio ||
@@ -209,8 +211,6 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n) 
		}

	}



	root_lock = qdisc_root_sleeping_lock(q);



	if (tp == NULL) {

		/* Proto-tcf does not exist, create new one */
@@ -259,7 +259,8 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n) 
		}

		tp->ops = tp_ops;

		tp->protocol = protocol;

		tp->prio = nprio ? : TC_H_MAJ(tcf_auto_prio(*back));

		tp->prio = nprio ? :

			       TC_H_MAJ(tcf_auto_prio(rtnl_dereference(*back)));

		tp->q = q;

		tp->classify = tp_ops->classify;

		tp->classid = parent;
@@ -280,9 +281,9 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n) 


	if (fh == 0) {

		if (n->nlmsg_type == RTM_DELTFILTER && t->tcm_handle == 0) {

			spin_lock_bh(root_lock);

			*back = tp->next;

			spin_unlock_bh(root_lock);

			struct tcf_proto *next = rtnl_dereference(tp->next);



			RCU_INIT_POINTER(*back, next);



			tfilter_notify(net, skb, n, tp, fh, RTM_DELTFILTER);

			tcf_destroy(tp);
@@ -322,10 +323,8 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n) 
			      n->nlmsg_flags & NLM_F_CREATE ? TCA_ACT_NOREPLACE : TCA_ACT_REPLACE);

	if (err == 0) {

		if (tp_created) {

			spin_lock_bh(root_lock);

			tp->next = *back;

			*back = tp;

			spin_unlock_bh(root_lock);

			RCU_INIT_POINTER(tp->next, rtnl_dereference(*back));

			rcu_assign_pointer(*back, tp);

		}

		tfilter_notify(net, skb, n, tp, fh, RTM_NEWTFILTER);

	} else {
@@ -420,7 +419,7 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb) 
	int s_t;

	struct net_device *dev;

	struct Qdisc *q;

	struct tcf_proto *tp, **chain;

	struct tcf_proto *tp, __rcu **chain;

	struct tcmsg *tcm = nlmsg_data(cb->nlh);

	unsigned long cl = 0;

	const struct Qdisc_class_ops *cops;
@@ -454,7 +453,8 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb) 


	s_t = cb->args[0];



	for (tp = *chain, t = 0; tp; tp = tp->next, t++) {

	for (tp = rtnl_dereference(*chain), t = 0;

	     tp; tp = rtnl_dereference(tp->next), t++) {

		if (t < s_t)

			continue;

		if (TC_H_MAJ(tcm->tcm_info) &&

net/sched/sch_api.c

+5 −5
Original line number Diff line number Diff line
@@ -1781,7 +1781,7 @@ int tc_classify_compat(struct sk_buff *skb, const struct tcf_proto *tp, 
	__be16 protocol = skb->protocol;

	int err;



	for (; tp; tp = tp->next) {

	for (; tp; tp = rcu_dereference_bh(tp->next)) {

		if (tp->protocol != protocol &&

		    tp->protocol != htons(ETH_P_ALL))

			continue;
@@ -1833,15 +1833,15 @@ void tcf_destroy(struct tcf_proto *tp) 
{

	tp->ops->destroy(tp);

	module_put(tp->ops->owner);

	kfree(tp);

	kfree_rcu(tp, rcu);

}



void tcf_destroy_chain(struct tcf_proto **fl)

void tcf_destroy_chain(struct tcf_proto __rcu **fl)

{

	struct tcf_proto *tp;



	while ((tp = *fl) != NULL) {

		*fl = tp->next;

	while ((tp = rtnl_dereference(*fl)) != NULL) {

		RCU_INIT_POINTER(*fl, tp->next);

		tcf_destroy(tp);

	}

}

net/sched/sch_atm.c

+11 −9
Original line number Diff line number Diff line
@@ -41,7 +41,7 @@ 


struct atm_flow_data {

	struct Qdisc		*q;	/* FIFO, TBF, etc. */

	struct tcf_proto	*filter_list;

	struct tcf_proto __rcu	*filter_list;

	struct atm_vcc		*vcc;	/* VCC; NULL if VCC is closed */

	void			(*old_pop)(struct atm_vcc *vcc,

					   struct sk_buff *skb); /* chaining */
@@ -273,7 +273,7 @@ static int atm_tc_change(struct Qdisc *sch, u32 classid, u32 parent, 
		error = -ENOBUFS;

		goto err_out;

	}

	flow->filter_list = NULL;

	RCU_INIT_POINTER(flow->filter_list, NULL);

	flow->q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, classid);

	if (!flow->q)

		flow->q = &noop_qdisc;
@@ -311,7 +311,7 @@ static int atm_tc_delete(struct Qdisc *sch, unsigned long arg) 
	pr_debug("atm_tc_delete(sch %p,[qdisc %p],flow %p)\n", sch, p, flow);

	if (list_empty(&flow->list))

		return -EINVAL;

	if (flow->filter_list || flow == &p->link)

	if (rcu_access_pointer(flow->filter_list) || flow == &p->link)

		return -EBUSY;

	/*

	 * Reference count must be 2: one for "keepalive" (set at class
@@ -345,7 +345,8 @@ static void atm_tc_walk(struct Qdisc *sch, struct qdisc_walker *walker) 
	}

}



static struct tcf_proto **atm_tc_find_tcf(struct Qdisc *sch, unsigned long cl)

static struct tcf_proto __rcu **atm_tc_find_tcf(struct Qdisc *sch,

						unsigned long cl)

{

	struct atm_qdisc_data *p = qdisc_priv(sch);

	struct atm_flow_data *flow = (struct atm_flow_data *)cl;
@@ -369,11 +370,12 @@ static int atm_tc_enqueue(struct sk_buff *skb, struct Qdisc *sch) 
	flow = NULL;

	if (TC_H_MAJ(skb->priority) != sch->handle ||

	    !(flow = (struct atm_flow_data *)atm_tc_get(sch, skb->priority))) {

		struct tcf_proto *fl;



		list_for_each_entry(flow, &p->flows, list) {

			if (flow->filter_list) {

				result = tc_classify_compat(skb,

							    flow->filter_list,

							    &res);

			fl = rcu_dereference_bh(flow->filter_list);

			if (fl) {

				result = tc_classify_compat(skb, fl, &res);

				if (result < 0)

					continue;

				flow = (struct atm_flow_data *)res.class;
@@ -544,7 +546,7 @@ static int atm_tc_init(struct Qdisc *sch, struct nlattr *opt) 
	if (!p->link.q)

		p->link.q = &noop_qdisc;

	pr_debug("atm_tc_init: link (%p) qdisc %p\n", &p->link, p->link.q);

	p->link.filter_list = NULL;

	RCU_INIT_POINTER(p->link.filter_list, NULL);

	p->link.vcc = NULL;

	p->link.sock = NULL;

	p->link.classid = sch->handle;

net/sched/sch_cbq.c

+7 −4
Original line number Diff line number Diff line
@@ -133,7 +133,7 @@ struct cbq_class { 
	struct gnet_stats_rate_est64 rate_est;

	struct tc_cbq_xstats	xstats;



	struct tcf_proto	*filter_list;

	struct tcf_proto __rcu	*filter_list;



	int			refcnt;

	int			filters;
@@ -221,6 +221,7 @@ cbq_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr) 
	struct cbq_class **defmap;

	struct cbq_class *cl = NULL;

	u32 prio = skb->priority;

	struct tcf_proto *fl;

	struct tcf_result res;



	/*
@@ -235,11 +236,12 @@ cbq_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr) 
		int result = 0;

		defmap = head->defaults;



		fl = rcu_dereference_bh(head->filter_list);

		/*

		 * Step 2+n. Apply classifier.

		 */

		if (!head->filter_list ||

		    (result = tc_classify_compat(skb, head->filter_list, &res)) < 0)

		result = tc_classify_compat(skb, fl, &res);

		if (!fl || result < 0)

			goto fallback;



		cl = (void *)res.class;
@@ -1954,7 +1956,8 @@ static int cbq_delete(struct Qdisc *sch, unsigned long arg) 
	return 0;

}



static struct tcf_proto **cbq_find_tcf(struct Qdisc *sch, unsigned long arg)

static struct tcf_proto __rcu **cbq_find_tcf(struct Qdisc *sch,

					     unsigned long arg)

{

	struct cbq_sched_data *q = qdisc_priv(sch);

	struct cbq_class *cl = (struct cbq_class *)arg;