net/sched: act_nat: transition to percpu stats and rcu

The tc action act_nat was using shared stats and taking the per action
lock in the datapath. Improve it by using percpu stats and rcu.

perf before:
- 10.48% tcf_nat_act
   - 81.83% _raw_spin_lock
        81.08% native_queued_spin_lock_slowpath

perf after:
- 0.48% tcf_nat_act

tdc results:
1..27
ok 1 7565 - Add nat action on ingress with default control action
ok 2 fd79 - Add nat action on ingress with pipe control action
ok 3 eab9 - Add nat action on ingress with continue control action
ok 4 c53a - Add nat action on ingress with reclassify control action
ok 5 76c9 - Add nat action on ingress with jump control action
ok 6 24c6 - Add nat action on ingress with drop control action
ok 7 2120 - Add nat action on ingress with maximum index value
ok 8 3e9d - Add nat action on ingress with invalid index value
ok 9 f6c9 - Add nat action on ingress with invalid IP address
ok 10 be25 - Add nat action on ingress with invalid argument
ok 11 a7bd - Add nat action on ingress with DEFAULT IP address
ok 12 ee1e - Add nat action on ingress with ANY IP address
ok 13 1de8 - Add nat action on ingress with ALL IP address
ok 14 8dba - Add nat action on egress with default control action
ok 15 19a7 - Add nat action on egress with pipe control action
ok 16 f1d9 - Add nat action on egress with continue control action
ok 17 6d4a - Add nat action on egress with reclassify control action
ok 18 b313 - Add nat action on egress with jump control action
ok 19 d9fc - Add nat action on egress with drop control action
ok 20 a895 - Add nat action on egress with DEFAULT IP address
ok 21 2572 - Add nat action on egress with ANY IP address
ok 22 37f3 - Add nat action on egress with ALL IP address
ok 23 6054 - Add nat action on egress with cookie
ok 24 79d6 - Add nat action on ingress with cookie
ok 25 4b12 - Replace nat action with invalid goto chain control
ok 26 b811 - Delete nat action with valid index
ok 27 a521 - Delete nat action with invalid index

Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/include/net/tc_act/tc_nat.h b/include/net/tc_act/tc_nat.h
index c144071..c869274 100644 (file)
--- a/include/net/tc_act/tc_nat.h
+++ b/include/net/tc_act/tc_nat.h
@@ -5,13 +5,17 @@
 #include <linux/types.h>
 #include <net/act_api.h>
 
-struct tcf_nat {
-       struct tc_action common;
-
+struct tcf_nat_parms {
        __be32 old_addr;
        __be32 new_addr;
        __be32 mask;
        u32 flags;
+       struct rcu_head rcu;
+};
+
+struct tcf_nat {
+       struct tc_action common;
+       struct tcf_nat_parms __rcu *parms;
 };
 
 #define to_tcf_nat(a) ((struct tcf_nat *)a)

diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
index 74c74be..4184af5 100644 (file)
--- a/net/sched/act_nat.c
+++ b/net/sched/act_nat.c
@@ -38,6 +38,7 @@ static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
 {
        struct tc_action_net *tn = net_generic(net, act_nat_ops.net_id);
        bool bind = flags & TCA_ACT_FLAGS_BIND;
+       struct tcf_nat_parms *nparm, *oparm;
        struct nlattr *tb[TCA_NAT_MAX + 1];
        struct tcf_chain *goto_ch = NULL;
        struct tc_nat *parm;
@@ -59,8 +60,8 @@ static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
        index = parm->index;
        err = tcf_idr_check_alloc(tn, &index, a, bind);
        if (!err) {
-               ret = tcf_idr_create(tn, index, est, a,
-                                    &act_nat_ops, bind, false, flags);
+               ret = tcf_idr_create_from_flags(tn, index, est, a, &act_nat_ops,
+                                               bind, flags);
                if (ret) {
                        tcf_idr_cleanup(tn, index);
                        return ret;
@@ -79,19 +80,31 @@ static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
        err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
        if (err < 0)
                goto release_idr;
+
+       nparm = kzalloc(sizeof(*nparm), GFP_KERNEL);
+       if (!nparm) {
+               err = -ENOMEM;
+               goto release_idr;
+       }
+
+       nparm->old_addr = parm->old_addr;
+       nparm->new_addr = parm->new_addr;
+       nparm->mask = parm->mask;
+       nparm->flags = parm->flags;
+
        p = to_tcf_nat(*a);
 
        spin_lock_bh(&p->tcf_lock);
-       p->old_addr = parm->old_addr;
-       p->new_addr = parm->new_addr;
-       p->mask = parm->mask;
-       p->flags = parm->flags;
-
        goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
+       oparm = rcu_replace_pointer(p->parms, nparm, lockdep_is_held(&p->tcf_lock));
        spin_unlock_bh(&p->tcf_lock);
+
        if (goto_ch)
                tcf_chain_put_by_act(goto_ch);
 
+       if (oparm)
+               kfree_rcu(oparm, rcu);
+
        return ret;
 release_idr:
        tcf_idr_release(*a, bind);
@@ -103,6 +116,7 @@ TC_INDIRECT_SCOPE int tcf_nat_act(struct sk_buff *skb,
                                  struct tcf_result *res)
 {
        struct tcf_nat *p = to_tcf_nat(a);
+       struct tcf_nat_parms *parms;
        struct iphdr *iph;
        __be32 old_addr;
        __be32 new_addr;
@@ -113,18 +127,16 @@ TC_INDIRECT_SCOPE int tcf_nat_act(struct sk_buff *skb,
        int ihl;
        int noff;
 
-       spin_lock(&p->tcf_lock);
-
        tcf_lastuse_update(&p->tcf_tm);
-       old_addr = p->old_addr;
-       new_addr = p->new_addr;
-       mask = p->mask;
-       egress = p->flags & TCA_NAT_FLAG_EGRESS;
-       action = p->tcf_action;
+       tcf_action_update_bstats(&p->common, skb);
 
-       bstats_update(&p->tcf_bstats, skb);
+       action = READ_ONCE(p->tcf_action);
 
-       spin_unlock(&p->tcf_lock);
+       parms = rcu_dereference_bh(p->parms);
+       old_addr = parms->old_addr;
+       new_addr = parms->new_addr;
+       mask = parms->mask;
+       egress = parms->flags & TCA_NAT_FLAG_EGRESS;
 
        if (unlikely(action == TC_ACT_SHOT))
                goto drop;
@@ -248,9 +260,7 @@ out:
        return action;
 
 drop:
-       spin_lock(&p->tcf_lock);
-       p->tcf_qstats.drops++;
-       spin_unlock(&p->tcf_lock);
+       tcf_action_inc_drop_qstats(&p->common);
        return TC_ACT_SHOT;
 }
 
@@ -264,15 +274,20 @@ static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
                .refcnt   = refcount_read(&p->tcf_refcnt) - ref,
                .bindcnt  = atomic_read(&p->tcf_bindcnt) - bind,
        };
+       struct tcf_nat_parms *parms;
        struct tcf_t t;
 
        spin_lock_bh(&p->tcf_lock);
-       opt.old_addr = p->old_addr;
-       opt.new_addr = p->new_addr;
-       opt.mask = p->mask;
-       opt.flags = p->flags;
+
        opt.action = p->tcf_action;
 
+       parms = rcu_dereference_protected(p->parms, lockdep_is_held(&p->tcf_lock));
+
+       opt.old_addr = parms->old_addr;
+       opt.new_addr = parms->new_addr;
+       opt.mask = parms->mask;
+       opt.flags = parms->flags;
+
        if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
                goto nla_put_failure;
 
@@ -289,6 +304,16 @@ nla_put_failure:
        return -1;
 }
 
+static void tcf_nat_cleanup(struct tc_action *a)
+{
+       struct tcf_nat *p = to_tcf_nat(a);
+       struct tcf_nat_parms *parms;
+
+       parms = rcu_dereference_protected(p->parms, 1);
+       if (parms)
+               kfree_rcu(parms, rcu);
+}
+
 static struct tc_action_ops act_nat_ops = {
        .kind           =       "nat",
        .id             =       TCA_ID_NAT,
@@ -296,6 +321,7 @@ static struct tc_action_ops act_nat_ops = {
        .act            =       tcf_nat_act,
        .dump           =       tcf_nat_dump,
        .init           =       tcf_nat_init,
+       .cleanup        =       tcf_nat_cleanup,
        .size           =       sizeof(struct tcf_nat),
 };