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Commit 1ce87720 authored by John Fastabend's avatar John Fastabend Committed by David S. Miller
Browse files

net: sched: make cls_u32 lockless 



Make cls_u32 classifier safe to run without holding lock. This patch
converts statistics that are kept in read section u32_classify into
per cpu counters.

This patch was tested with a tight u32 filter add/delete loop while
generating traffic with pktgen. By running pktgen on vlan devices
created on top of a physical device we can hit the qdisc layer
correctly. For ingress qdisc's a loopback cable was used.

for i in {1..100}; do
        q=`echo $i%8|bc`;
        echo -n "u32 tos: iteration $i on queue $q";
        tc filter add dev p3p2 parent $p prio $i u32 match ip tos 0x10 0xff \
                  action skbedit queue_mapping $q;
        sleep 1;
        tc filter del dev p3p2 prio $i;

        echo -n "u32 tos hash table: iteration $i on queue $q";
        tc filter add dev p3p2 parent $p protocol ip prio $i handle 628: u32 divisor 1
        tc filter add dev p3p2 parent $p protocol ip prio $i u32 \
                match ip protocol 17 0xff link 628: offset at 0 mask 0xf00 shift 6 plus 0
        tc filter add dev p3p2 parent $p protocol ip prio $i u32 \
                ht 628:0 match ip tos 0x10 0xff action skbedit queue_mapping $q
        sleep 2;
        tc filter del dev p3p2 prio $i
        sleep 1;
done

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 459d5f62

net/sched/cls_u32.c

+110 −73
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ 
#include <linux/kernel.h>

#include <linux/string.h>

#include <linux/errno.h>

#include <linux/percpu.h>

#include <linux/rtnetlink.h>

#include <linux/skbuff.h>

#include <linux/bitmap.h>
@@ -44,16 +45,16 @@ 
#include <net/pkt_cls.h>



struct tc_u_knode {

	struct tc_u_knode	*next;

	struct tc_u_knode __rcu	*next;

	u32			handle;

	struct tc_u_hnode	*ht_up;

	struct tc_u_hnode __rcu	*ht_up;

	struct tcf_exts		exts;

#ifdef CONFIG_NET_CLS_IND

	int			ifindex;

#endif

	u8			fshift;

	struct tcf_result	res;

	struct tc_u_hnode	*ht_down;

	struct tc_u_hnode __rcu	*ht_down;

#ifdef CONFIG_CLS_U32_PERF

	struct tc_u32_pcnt __percpu *pf;

#endif
@@ -62,24 +63,28 @@ struct tc_u_knode { 
	u32			mask;

	u32 __percpu		*pcpu_success;

#endif

	struct tcf_proto	*tp;

	struct tc_u32_sel	sel;

	struct rcu_head		rcu;

};



struct tc_u_hnode {

	struct tc_u_hnode	*next;

	struct tc_u_hnode __rcu	*next;

	u32			handle;

	u32			prio;

	struct tc_u_common	*tp_c;

	int			refcnt;

	unsigned int		divisor;

	struct tc_u_knode	*ht[1];

	struct tc_u_knode __rcu	*ht[1];

	struct rcu_head		rcu;

};



struct tc_u_common {

	struct tc_u_hnode	*hlist;

	struct tc_u_hnode __rcu	*hlist;

	struct Qdisc		*q;

	int			refcnt;

	u32			hgenerator;

	struct rcu_head		rcu;

};



static inline unsigned int u32_hash_fold(__be32 key,
@@ -98,7 +103,7 @@ static int u32_classify(struct sk_buff *skb, const struct tcf_proto *tp, struct 
		unsigned int	  off;

	} stack[TC_U32_MAXDEPTH];



	struct tc_u_hnode *ht = tp->root;

	struct tc_u_hnode *ht = rcu_dereference_bh(tp->root);

	unsigned int off = skb_network_offset(skb);

	struct tc_u_knode *n;

	int sdepth = 0;
@@ -110,7 +115,7 @@ static int u32_classify(struct sk_buff *skb, const struct tcf_proto *tp, struct 
	int i, r;



next_ht:

	n = ht->ht[sel];

	n = rcu_dereference_bh(ht->ht[sel]);



next_knode:

	if (n) {
@@ -123,7 +128,7 @@ static int u32_classify(struct sk_buff *skb, const struct tcf_proto *tp, struct 


#ifdef CONFIG_CLS_U32_MARK

		if ((skb->mark & n->mask) != n->val) {

			n = n->next;

			n = rcu_dereference_bh(n->next);

			goto next_knode;

		} else {

			__this_cpu_inc(*n->pcpu_success);
@@ -141,7 +146,7 @@ static int u32_classify(struct sk_buff *skb, const struct tcf_proto *tp, struct 
			if (!data)

				goto out;

			if ((*data ^ key->val) & key->mask) {

				n = n->next;

				n = rcu_dereference_bh(n->next);

				goto next_knode;

			}

#ifdef CONFIG_CLS_U32_PERF
@@ -149,14 +154,16 @@ static int u32_classify(struct sk_buff *skb, const struct tcf_proto *tp, struct 
			j++;

#endif

		}

		if (n->ht_down == NULL) {



		ht = rcu_dereference_bh(n->ht_down);

		if (!ht) {

check_terminal:

			if (n->sel.flags & TC_U32_TERMINAL) {



				*res = n->res;

#ifdef CONFIG_NET_CLS_IND

				if (!tcf_match_indev(skb, n->ifindex)) {

					n = n->next;

					n = rcu_dereference_bh(n->next);

					goto next_knode;

				}

#endif
@@ -165,13 +172,13 @@ static int u32_classify(struct sk_buff *skb, const struct tcf_proto *tp, struct 
#endif

				r = tcf_exts_exec(skb, &n->exts, res);

				if (r < 0) {

					n = n->next;

					n = rcu_dereference_bh(n->next);

					goto next_knode;

				}



				return r;

			}

			n = n->next;

			n = rcu_dereference_bh(n->next);

			goto next_knode;

		}
@@ -182,7 +189,7 @@ static int u32_classify(struct sk_buff *skb, const struct tcf_proto *tp, struct 
		stack[sdepth].off = off;

		sdepth++;



		ht = n->ht_down;

		ht = rcu_dereference_bh(n->ht_down);

		sel = 0;

		if (ht->divisor) {

			__be32 *data, hdata;
@@ -224,7 +231,7 @@ static int u32_classify(struct sk_buff *skb, const struct tcf_proto *tp, struct 
	/* POP */

	if (sdepth--) {

		n = stack[sdepth].knode;

		ht = n->ht_up;

		ht = rcu_dereference_bh(n->ht_up);

		off = stack[sdepth].off;

		goto check_terminal;

	}
@@ -241,7 +248,9 @@ u32_lookup_ht(struct tc_u_common *tp_c, u32 handle) 
{

	struct tc_u_hnode *ht;



	for (ht = tp_c->hlist; ht; ht = ht->next)

	for (ht = rtnl_dereference(tp_c->hlist);

	     ht;

	     ht = rtnl_dereference(ht->next))

		if (ht->handle == handle)

			break;
@@ -258,7 +267,9 @@ u32_lookup_key(struct tc_u_hnode *ht, u32 handle) 
	if (sel > ht->divisor)

		goto out;



	for (n = ht->ht[sel]; n; n = n->next)

	for (n = rtnl_dereference(ht->ht[sel]);

	     n;

	     n = rtnl_dereference(n->next))

		if (n->handle == handle)

			break;

out:
@@ -272,7 +283,7 @@ static unsigned long u32_get(struct tcf_proto *tp, u32 handle) 
	struct tc_u_common *tp_c = tp->data;



	if (TC_U32_HTID(handle) == TC_U32_ROOT)

		ht = tp->root;

		ht = rtnl_dereference(tp->root);

	else

		ht = u32_lookup_ht(tp_c, TC_U32_HTID(handle));
@@ -293,6 +304,9 @@ static u32 gen_new_htid(struct tc_u_common *tp_c) 
{

	int i = 0x800;



	/* hgenerator only used inside rtnl lock it is safe to increment

	 * without read _copy_ update semantics

	 */

	do {

		if (++tp_c->hgenerator == 0x7FF)

			tp_c->hgenerator = 1;
@@ -328,11 +342,11 @@ static int u32_init(struct tcf_proto *tp) 
	}



	tp_c->refcnt++;

	root_ht->next = tp_c->hlist;

	tp_c->hlist = root_ht;

	RCU_INIT_POINTER(root_ht->next, tp_c->hlist);

	rcu_assign_pointer(tp_c->hlist, root_ht);

	root_ht->tp_c = tp_c;



	tp->root = root_ht;

	rcu_assign_pointer(tp->root, root_ht);

	tp->data = tp_c;

	return 0;

}
@@ -350,19 +364,27 @@ static int u32_destroy_key(struct tcf_proto *tp, struct tc_u_knode *n) 
	return 0;

}



static void u32_delete_key_rcu(struct rcu_head *rcu)

{

	struct tc_u_knode *key = container_of(rcu, struct tc_u_knode, rcu);



	u32_destroy_key(key->tp, key);

}



static int u32_delete_key(struct tcf_proto *tp, struct tc_u_knode *key)

{

	struct tc_u_knode **kp;

	struct tc_u_knode __rcu **kp;

	struct tc_u_knode *pkp;

	struct tc_u_hnode *ht = key->ht_up;



	if (ht) {

		for (kp = &ht->ht[TC_U32_HASH(key->handle)]; *kp; kp = &(*kp)->next) {

			if (*kp == key) {

				tcf_tree_lock(tp);

				*kp = key->next;

				tcf_tree_unlock(tp);

		kp = &ht->ht[TC_U32_HASH(key->handle)];

		for (pkp = rtnl_dereference(*kp); pkp;

		     kp = &pkp->next, pkp = rtnl_dereference(*kp)) {

			if (pkp == key) {

				RCU_INIT_POINTER(*kp, key->next);



				u32_destroy_key(tp, key);

				call_rcu(&key->rcu, u32_delete_key_rcu);

				return 0;

			}

		}
@@ -371,16 +393,16 @@ static int u32_delete_key(struct tcf_proto *tp, struct tc_u_knode *key) 
	return 0;

}



static void u32_clear_hnode(struct tcf_proto *tp, struct tc_u_hnode *ht)

static void u32_clear_hnode(struct tc_u_hnode *ht)

{

	struct tc_u_knode *n;

	unsigned int h;



	for (h = 0; h <= ht->divisor; h++) {

		while ((n = ht->ht[h]) != NULL) {

			ht->ht[h] = n->next;



			u32_destroy_key(tp, n);

		while ((n = rtnl_dereference(ht->ht[h])) != NULL) {

			RCU_INIT_POINTER(ht->ht[h],

					 rtnl_dereference(n->next));

			call_rcu(&n->rcu, u32_delete_key_rcu);

		}

	}

}
@@ -388,28 +410,31 @@ static void u32_clear_hnode(struct tcf_proto *tp, struct tc_u_hnode *ht) 
static int u32_destroy_hnode(struct tcf_proto *tp, struct tc_u_hnode *ht)

{

	struct tc_u_common *tp_c = tp->data;

	struct tc_u_hnode **hn;

	struct tc_u_hnode __rcu **hn;

	struct tc_u_hnode *phn;



	WARN_ON(ht->refcnt);



	u32_clear_hnode(tp, ht);

	u32_clear_hnode(ht);



	for (hn = &tp_c->hlist; *hn; hn = &(*hn)->next) {

		if (*hn == ht) {

			*hn = ht->next;

			kfree(ht);

	hn = &tp_c->hlist;

	for (phn = rtnl_dereference(*hn);

	     phn;

	     hn = &phn->next, phn = rtnl_dereference(*hn)) {

		if (phn == ht) {

			RCU_INIT_POINTER(*hn, ht->next);

			kfree_rcu(ht, rcu);

			return 0;

		}

	}



	WARN_ON(1);

	return -ENOENT;

}



static void u32_destroy(struct tcf_proto *tp)

{

	struct tc_u_common *tp_c = tp->data;

	struct tc_u_hnode *root_ht = tp->root;

	struct tc_u_hnode *root_ht = rtnl_dereference(tp->root);



	WARN_ON(root_ht == NULL);
@@ -421,17 +446,16 @@ static void u32_destroy(struct tcf_proto *tp) 


		tp->q->u32_node = NULL;



		for (ht = tp_c->hlist; ht; ht = ht->next) {

		for (ht = rtnl_dereference(tp_c->hlist);

		     ht;

		     ht = rtnl_dereference(ht->next)) {

			ht->refcnt--;

			u32_clear_hnode(tp, ht);

			u32_clear_hnode(ht);

		}



		while ((ht = tp_c->hlist) != NULL) {

			tp_c->hlist = ht->next;



			WARN_ON(ht->refcnt != 0);



			kfree(ht);

		while ((ht = rtnl_dereference(tp_c->hlist)) != NULL) {

			RCU_INIT_POINTER(tp_c->hlist, ht->next);

			kfree_rcu(ht, rcu);

		}



		kfree(tp_c);
@@ -443,6 +467,7 @@ static void u32_destroy(struct tcf_proto *tp) 
static int u32_delete(struct tcf_proto *tp, unsigned long arg)

{

	struct tc_u_hnode *ht = (struct tc_u_hnode *)arg;

	struct tc_u_hnode *root_ht = rtnl_dereference(tp->root);



	if (ht == NULL)

		return 0;
@@ -450,7 +475,7 @@ static int u32_delete(struct tcf_proto *tp, unsigned long arg) 
	if (TC_U32_KEY(ht->handle))

		return u32_delete_key(tp, (struct tc_u_knode *)ht);



	if (tp->root == ht)

	if (root_ht == ht)

		return -EINVAL;



	if (ht->refcnt == 1) {
@@ -473,7 +498,9 @@ static u32 gen_new_kid(struct tc_u_hnode *ht, u32 handle) 
	if (!bitmap)

		return handle | 0xFFF;



	for (n = ht->ht[TC_U32_HASH(handle)]; n; n = n->next)

	for (n = rtnl_dereference(ht->ht[TC_U32_HASH(handle)]);

	     n;

	     n = rtnl_dereference(n->next))

		set_bit(TC_U32_NODE(n->handle), bitmap);



	i = find_next_zero_bit(bitmap, NR_U32_NODE, 0x800);
@@ -523,10 +550,8 @@ static int u32_set_parms(struct net *net, struct tcf_proto *tp, 
			ht_down->refcnt++;

		}



		tcf_tree_lock(tp);

		ht_old = n->ht_down;

		n->ht_down = ht_down;

		tcf_tree_unlock(tp);

		ht_old = rtnl_dereference(n->ht_down);

		rcu_assign_pointer(n->ht_down, ht_down);



		if (ht_old)

			ht_old->refcnt--;
@@ -606,8 +631,8 @@ static int u32_change(struct net *net, struct sk_buff *in_skb, 
		ht->divisor = divisor;

		ht->handle = handle;

		ht->prio = tp->prio;

		ht->next = tp_c->hlist;

		tp_c->hlist = ht;

		RCU_INIT_POINTER(ht->next, tp_c->hlist);

		rcu_assign_pointer(tp_c->hlist, ht);

		*arg = (unsigned long)ht;

		return 0;

	}
@@ -615,7 +640,7 @@ static int u32_change(struct net *net, struct sk_buff *in_skb, 
	if (tb[TCA_U32_HASH]) {

		htid = nla_get_u32(tb[TCA_U32_HASH]);

		if (TC_U32_HTID(htid) == TC_U32_ROOT) {

			ht = tp->root;

			ht = rtnl_dereference(tp->root);

			htid = ht->handle;

		} else {

			ht = u32_lookup_ht(tp->data, TC_U32_HTID(htid));
@@ -623,7 +648,7 @@ static int u32_change(struct net *net, struct sk_buff *in_skb, 
				return -EINVAL;

		}

	} else {

		ht = tp->root;

		ht = rtnl_dereference(tp->root);

		htid = ht->handle;

	}
@@ -660,6 +685,7 @@ static int u32_change(struct net *net, struct sk_buff *in_skb, 
	n->handle = handle;

	n->fshift = s->hmask ? ffs(ntohl(s->hmask)) - 1 : 0;

	tcf_exts_init(&n->exts, TCA_U32_ACT, TCA_U32_POLICE);

	n->tp = tp;



#ifdef CONFIG_CLS_U32_MARK

	n->pcpu_success = alloc_percpu(u32);
@@ -675,21 +701,23 @@ static int u32_change(struct net *net, struct sk_buff *in_skb, 


	err = u32_set_parms(net, tp, base, ht, n, tb, tca[TCA_RATE], ovr);

	if (err == 0) {

		struct tc_u_knode **ins;

		for (ins = &ht->ht[TC_U32_HASH(handle)]; *ins; ins = &(*ins)->next)

			if (TC_U32_NODE(handle) < TC_U32_NODE((*ins)->handle))

		struct tc_u_knode __rcu **ins;

		struct tc_u_knode *pins;



		ins = &ht->ht[TC_U32_HASH(handle)];

		for (pins = rtnl_dereference(*ins); pins;

		     ins = &pins->next, pins = rtnl_dereference(*ins))

			if (TC_U32_NODE(handle) < TC_U32_NODE(pins->handle))

				break;



		n->next = *ins;

		tcf_tree_lock(tp);

		*ins = n;

		tcf_tree_unlock(tp);

		RCU_INIT_POINTER(n->next, pins);

		rcu_assign_pointer(*ins, n);



		*arg = (unsigned long)n;

		return 0;

	}

#ifdef CONFIG_CLS_U32_PERF

	kfree(n->pf);

	free_percpu(n->pf);

#endif

	kfree(n);

	return err;
@@ -705,7 +733,9 @@ static void u32_walk(struct tcf_proto *tp, struct tcf_walker *arg) 
	if (arg->stop)

		return;



	for (ht = tp_c->hlist; ht; ht = ht->next) {

	for (ht = rtnl_dereference(tp_c->hlist);

	     ht;

	     ht = rtnl_dereference(ht->next)) {

		if (ht->prio != tp->prio)

			continue;

		if (arg->count >= arg->skip) {
@@ -716,7 +746,9 @@ static void u32_walk(struct tcf_proto *tp, struct tcf_walker *arg) 
		}

		arg->count++;

		for (h = 0; h <= ht->divisor; h++) {

			for (n = ht->ht[h]; n; n = n->next) {

			for (n = rtnl_dereference(ht->ht[h]);

			     n;

			     n = rtnl_dereference(n->next)) {

				if (arg->count < arg->skip) {

					arg->count++;

					continue;
@@ -735,6 +767,7 @@ static int u32_dump(struct net *net, struct tcf_proto *tp, unsigned long fh, 
		     struct sk_buff *skb, struct tcmsg *t)

{

	struct tc_u_knode *n = (struct tc_u_knode *)fh;

	struct tc_u_hnode *ht_up, *ht_down;

	struct nlattr *nest;



	if (n == NULL)
@@ -762,7 +795,9 @@ static int u32_dump(struct net *net, struct tcf_proto *tp, unsigned long fh, 
			    sizeof(n->sel) + n->sel.nkeys*sizeof(struct tc_u32_key),

			    &n->sel))

			goto nla_put_failure;

		if (n->ht_up) {



		ht_up = rtnl_dereference(n->ht_up);

		if (ht_up) {

			u32 htid = n->handle & 0xFFFFF000;

			if (nla_put_u32(skb, TCA_U32_HASH, htid))

				goto nla_put_failure;
@@ -770,8 +805,10 @@ static int u32_dump(struct net *net, struct tcf_proto *tp, unsigned long fh, 
		if (n->res.classid &&

		    nla_put_u32(skb, TCA_U32_CLASSID, n->res.classid))

			goto nla_put_failure;

		if (n->ht_down &&

		    nla_put_u32(skb, TCA_U32_LINK, n->ht_down->handle))



		ht_down = rtnl_dereference(n->ht_down);

		if (ht_down &&

		    nla_put_u32(skb, TCA_U32_LINK, ht_down->handle))

			goto nla_put_failure;



#ifdef CONFIG_CLS_U32_MARK