Commit c749cdda authored by Davide Caratti's avatar Davide Caratti Committed by David S. Miller
Browse files

net/sched: act_skbedit: don't use spinlock in the data path 



use RCU instead of spin_{,un}lock_bh, to protect concurrent read/write on
act_skbedit configuration. This reduces the effects of contention in the
data path, in case multiple readers are present.

Signed-off-by: default avatarDavide Caratti <dcaratti@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6f3dfb0d

include/net/tc_act/tc_skbedit.h

+27 −10
Original line number Diff line number Diff line
@@ -22,14 +22,19 @@ 
#include <net/act_api.h>

#include <linux/tc_act/tc_skbedit.h>



struct tcf_skbedit {

	struct tc_action	common;

struct tcf_skbedit_params {

	u32 flags;

	u32 priority;

	u32 mark;

	u32 mask;

	u16 queue_mapping;

	u16 ptype;

	struct rcu_head rcu;

};



struct tcf_skbedit {

	struct tc_action common;

	struct tcf_skbedit_params __rcu *params;

};

#define to_skbedit(a) ((struct tcf_skbedit *)a)
@@ -37,15 +42,27 @@ struct tcf_skbedit { 
static inline bool is_tcf_skbedit_mark(const struct tc_action *a)

{

#ifdef CONFIG_NET_CLS_ACT

	if (a->ops && a->ops->type == TCA_ACT_SKBEDIT)

		return to_skbedit(a)->flags == SKBEDIT_F_MARK;

	u32 flags;



	if (a->ops && a->ops->type == TCA_ACT_SKBEDIT) {

		rcu_read_lock();

		flags = rcu_dereference(to_skbedit(a)->params)->flags;

		rcu_read_unlock();

		return flags == SKBEDIT_F_MARK;

	}

#endif

	return false;

}



static inline u32 tcf_skbedit_mark(const struct tc_action *a)

{

	return to_skbedit(a)->mark;

	u32 mark;



	rcu_read_lock();

	mark = rcu_dereference(to_skbedit(a)->params)->mark;

	rcu_read_unlock();



	return mark;

}



#endif /* __NET_TC_SKBEDIT_H */

net/sched/act_skbedit.c

+68 −39
Original line number Diff line number Diff line
@@ -37,14 +37,19 @@ static int tcf_skbedit(struct sk_buff *skb, const struct tc_action *a, 
		       struct tcf_result *res)

{

	struct tcf_skbedit *d = to_skbedit(a);

	struct tcf_skbedit_params *params;

	int action;



	tcf_lastuse_update(&d->tcf_tm);

	bstats_cpu_update(this_cpu_ptr(d->common.cpu_bstats), skb);



	spin_lock(&d->tcf_lock);

	if (d->flags & SKBEDIT_F_PRIORITY)

		skb->priority = d->priority;

	if (d->flags & SKBEDIT_F_INHERITDSFIELD) {

	rcu_read_lock();

	params = rcu_dereference(d->params);

	action = READ_ONCE(d->tcf_action);



	if (params->flags & SKBEDIT_F_PRIORITY)

		skb->priority = params->priority;

	if (params->flags & SKBEDIT_F_INHERITDSFIELD) {

		int wlen = skb_network_offset(skb);



		switch (tc_skb_protocol(skb)) {
@@ -63,23 +68,23 @@ static int tcf_skbedit(struct sk_buff *skb, const struct tc_action *a, 
			break;

		}

	}

	if (d->flags & SKBEDIT_F_QUEUE_MAPPING &&

	    skb->dev->real_num_tx_queues > d->queue_mapping)

		skb_set_queue_mapping(skb, d->queue_mapping);

	if (d->flags & SKBEDIT_F_MARK) {

		skb->mark &= ~d->mask;

		skb->mark |= d->mark & d->mask;

	if (params->flags & SKBEDIT_F_QUEUE_MAPPING &&

	    skb->dev->real_num_tx_queues > params->queue_mapping)

		skb_set_queue_mapping(skb, params->queue_mapping);

	if (params->flags & SKBEDIT_F_MARK) {

		skb->mark &= ~params->mask;

		skb->mark |= params->mark & params->mask;

	}

	if (d->flags & SKBEDIT_F_PTYPE)

		skb->pkt_type = d->ptype;



	spin_unlock(&d->tcf_lock);

	return d->tcf_action;

	if (params->flags & SKBEDIT_F_PTYPE)

		skb->pkt_type = params->ptype;



unlock:

	rcu_read_unlock();

	return action;

err:

	spin_unlock(&d->tcf_lock);

	qstats_drop_inc(this_cpu_ptr(d->common.cpu_qstats));

	return TC_ACT_SHOT;

	action = TC_ACT_SHOT;

	goto unlock;

}



static const struct nla_policy skbedit_policy[TCA_SKBEDIT_MAX + 1] = {
@@ -98,6 +103,7 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla, 
			    struct netlink_ext_ack *extack)

{

	struct tc_action_net *tn = net_generic(net, skbedit_net_id);

	struct tcf_skbedit_params *params_old, *params_new;

	struct nlattr *tb[TCA_SKBEDIT_MAX + 1];

	struct tc_skbedit *parm;

	struct tcf_skbedit *d;
@@ -185,25 +191,34 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla, 
		}

	}



	spin_lock_bh(&d->tcf_lock);

	ASSERT_RTNL();



	params_new = kzalloc(sizeof(*params_new), GFP_KERNEL);

	if (unlikely(!params_new)) {

		if (ret == ACT_P_CREATED)

			tcf_idr_release(*a, bind);

		return -ENOMEM;

	}



	d->flags = flags;

	params_new->flags = flags;

	if (flags & SKBEDIT_F_PRIORITY)

		d->priority = *priority;

		params_new->priority = *priority;

	if (flags & SKBEDIT_F_QUEUE_MAPPING)

		d->queue_mapping = *queue_mapping;

		params_new->queue_mapping = *queue_mapping;

	if (flags & SKBEDIT_F_MARK)

		d->mark = *mark;

		params_new->mark = *mark;

	if (flags & SKBEDIT_F_PTYPE)

		d->ptype = *ptype;

		params_new->ptype = *ptype;

	/* default behaviour is to use all the bits */

	d->mask = 0xffffffff;

	params_new->mask = 0xffffffff;

	if (flags & SKBEDIT_F_MASK)

		d->mask = *mask;

		params_new->mask = *mask;



	d->tcf_action = parm->action;



	spin_unlock_bh(&d->tcf_lock);

	params_old = rtnl_dereference(d->params);

	rcu_assign_pointer(d->params, params_new);

	if (params_old)

		kfree_rcu(params_old, rcu);



	if (ret == ACT_P_CREATED)

		tcf_idr_insert(tn, *a);
@@ -215,33 +230,36 @@ static int tcf_skbedit_dump(struct sk_buff *skb, struct tc_action *a, 
{

	unsigned char *b = skb_tail_pointer(skb);

	struct tcf_skbedit *d = to_skbedit(a);

	struct tcf_skbedit_params *params;

	struct tc_skbedit opt = {

		.index   = d->tcf_index,

		.refcnt  = refcount_read(&d->tcf_refcnt) - ref,

		.bindcnt = atomic_read(&d->tcf_bindcnt) - bind,

		.action  = d->tcf_action,

	};

	struct tcf_t t;

	u64 pure_flags = 0;

	struct tcf_t t;



	params = rtnl_dereference(d->params);



	if (nla_put(skb, TCA_SKBEDIT_PARMS, sizeof(opt), &opt))

		goto nla_put_failure;

	if ((d->flags & SKBEDIT_F_PRIORITY) &&

	    nla_put_u32(skb, TCA_SKBEDIT_PRIORITY, d->priority))

	if ((params->flags & SKBEDIT_F_PRIORITY) &&

	    nla_put_u32(skb, TCA_SKBEDIT_PRIORITY, params->priority))

		goto nla_put_failure;

	if ((d->flags & SKBEDIT_F_QUEUE_MAPPING) &&

	    nla_put_u16(skb, TCA_SKBEDIT_QUEUE_MAPPING, d->queue_mapping))

	if ((params->flags & SKBEDIT_F_QUEUE_MAPPING) &&

	    nla_put_u16(skb, TCA_SKBEDIT_QUEUE_MAPPING, params->queue_mapping))

		goto nla_put_failure;

	if ((d->flags & SKBEDIT_F_MARK) &&

	    nla_put_u32(skb, TCA_SKBEDIT_MARK, d->mark))

	if ((params->flags & SKBEDIT_F_MARK) &&

	    nla_put_u32(skb, TCA_SKBEDIT_MARK, params->mark))

		goto nla_put_failure;

	if ((d->flags & SKBEDIT_F_PTYPE) &&

	    nla_put_u16(skb, TCA_SKBEDIT_PTYPE, d->ptype))

	if ((params->flags & SKBEDIT_F_PTYPE) &&

	    nla_put_u16(skb, TCA_SKBEDIT_PTYPE, params->ptype))

		goto nla_put_failure;

	if ((d->flags & SKBEDIT_F_MASK) &&

	    nla_put_u32(skb, TCA_SKBEDIT_MASK, d->mask))

	if ((params->flags & SKBEDIT_F_MASK) &&

	    nla_put_u32(skb, TCA_SKBEDIT_MASK, params->mask))

		goto nla_put_failure;

	if (d->flags & SKBEDIT_F_INHERITDSFIELD)

	if (params->flags & SKBEDIT_F_INHERITDSFIELD)

		pure_flags |= SKBEDIT_F_INHERITDSFIELD;

	if (pure_flags != 0 &&

	    nla_put(skb, TCA_SKBEDIT_FLAGS, sizeof(pure_flags), &pure_flags))
@@ -257,6 +275,16 @@ nla_put_failure: 
	return -1;

}



static void tcf_skbedit_cleanup(struct tc_action *a)

{

	struct tcf_skbedit *d = to_skbedit(a);

	struct tcf_skbedit_params *params;



	params = rcu_dereference_protected(d->params, 1);

	if (params)

		kfree_rcu(params, rcu);

}



static int tcf_skbedit_walker(struct net *net, struct sk_buff *skb,

			      struct netlink_callback *cb, int type,

			      const struct tc_action_ops *ops,
@@ -289,6 +317,7 @@ static struct tc_action_ops act_skbedit_ops = { 
	.act		=	tcf_skbedit,

	.dump		=	tcf_skbedit_dump,

	.init		=	tcf_skbedit_init,

	.cleanup	=	tcf_skbedit_cleanup,

	.walk		=	tcf_skbedit_walker,

	.lookup		=	tcf_skbedit_search,

	.delete		=	tcf_skbedit_delete,

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