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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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net/sched: act_csum: don't use spinlock in the fast path
use RCU instead of spin_{,unlock}_bh() to protect concurrent read/write on
act_csum configuration, to reduce the effects of contention in the data
path when multiple readers are present.
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Davide Caratti
David S. Miller
parent
f6052cf2fc
commit
9c5f69bbd7
@ -6,10 +6,16 @@
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#include <net/act_api.h>
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#include <linux/tc_act/tc_csum.h>
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struct tcf_csum_params {
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int action;
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u32 update_flags;
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struct rcu_head rcu;
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};
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struct tcf_csum {
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struct tc_action common;
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u32 update_flags;
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struct tcf_csum_params __rcu *params;
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};
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#define to_tcf_csum(a) ((struct tcf_csum *)a)
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@ -24,7 +30,13 @@ static inline bool is_tcf_csum(const struct tc_action *a)
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static inline u32 tcf_csum_update_flags(const struct tc_action *a)
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{
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return to_tcf_csum(a)->update_flags;
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u32 update_flags;
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rcu_read_lock();
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update_flags = rcu_dereference(to_tcf_csum(a)->params)->update_flags;
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rcu_read_unlock();
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return update_flags;
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}
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#endif /* __NET_TC_CSUM_H */
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@ -49,6 +49,7 @@ static int tcf_csum_init(struct net *net, struct nlattr *nla,
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int bind)
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{
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struct tc_action_net *tn = net_generic(net, csum_net_id);
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struct tcf_csum_params *params_old, *params_new;
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struct nlattr *tb[TCA_CSUM_MAX + 1];
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struct tc_csum *parm;
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struct tcf_csum *p;
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@ -80,10 +81,21 @@ static int tcf_csum_init(struct net *net, struct nlattr *nla,
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}
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p = to_tcf_csum(*a);
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spin_lock_bh(&p->tcf_lock);
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p->tcf_action = parm->action;
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p->update_flags = parm->update_flags;
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spin_unlock_bh(&p->tcf_lock);
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ASSERT_RTNL();
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params_new = kzalloc(sizeof(*params_new), GFP_KERNEL);
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if (unlikely(!params_new)) {
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if (ret == ACT_P_CREATED)
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tcf_idr_release(*a, bind);
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return -ENOMEM;
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}
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params_old = rtnl_dereference(p->params);
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params_new->action = parm->action;
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params_new->update_flags = parm->update_flags;
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rcu_assign_pointer(p->params, params_new);
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if (params_old)
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kfree_rcu(params_old, rcu);
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if (ret == ACT_P_CREATED)
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tcf_idr_insert(tn, *a);
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@ -539,19 +551,21 @@ static int tcf_csum(struct sk_buff *skb, const struct tc_action *a,
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struct tcf_result *res)
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{
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struct tcf_csum *p = to_tcf_csum(a);
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int action;
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struct tcf_csum_params *params;
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u32 update_flags;
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int action;
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rcu_read_lock();
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params = rcu_dereference(p->params);
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tcf_lastuse_update(&p->tcf_tm);
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bstats_cpu_update(this_cpu_ptr(p->common.cpu_bstats), skb);
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spin_lock(&p->tcf_lock);
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action = p->tcf_action;
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update_flags = p->update_flags;
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spin_unlock(&p->tcf_lock);
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action = params->action;
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if (unlikely(action == TC_ACT_SHOT))
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goto drop;
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goto drop_stats;
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update_flags = params->update_flags;
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switch (tc_skb_protocol(skb)) {
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case cpu_to_be16(ETH_P_IP):
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if (!tcf_csum_ipv4(skb, update_flags))
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@ -563,11 +577,16 @@ static int tcf_csum(struct sk_buff *skb, const struct tc_action *a,
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break;
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}
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unlock:
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rcu_read_unlock();
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return action;
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drop:
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action = TC_ACT_SHOT;
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drop_stats:
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qstats_drop_inc(this_cpu_ptr(p->common.cpu_qstats));
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return TC_ACT_SHOT;
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goto unlock;
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}
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static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind,
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@ -575,15 +594,18 @@ static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind,
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{
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unsigned char *b = skb_tail_pointer(skb);
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struct tcf_csum *p = to_tcf_csum(a);
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struct tcf_csum_params *params;
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struct tc_csum opt = {
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.update_flags = p->update_flags,
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.index = p->tcf_index,
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.action = p->tcf_action,
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.refcnt = p->tcf_refcnt - ref,
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.bindcnt = p->tcf_bindcnt - bind,
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};
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struct tcf_t t;
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params = rtnl_dereference(p->params);
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opt.action = params->action;
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opt.update_flags = params->update_flags;
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if (nla_put(skb, TCA_CSUM_PARMS, sizeof(opt), &opt))
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goto nla_put_failure;
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@ -598,6 +620,15 @@ static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind,
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return -1;
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}
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static void tcf_csum_cleanup(struct tc_action *a)
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{
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struct tcf_csum *p = to_tcf_csum(a);
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struct tcf_csum_params *params;
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params = rcu_dereference_protected(p->params, 1);
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kfree_rcu(params, rcu);
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}
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static int tcf_csum_walker(struct net *net, struct sk_buff *skb,
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struct netlink_callback *cb, int type,
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const struct tc_action_ops *ops)
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@ -621,6 +652,7 @@ static struct tc_action_ops act_csum_ops = {
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.act = tcf_csum,
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.dump = tcf_csum_dump,
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.init = tcf_csum_init,
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.cleanup = tcf_csum_cleanup,
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.walk = tcf_csum_walker,
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.lookup = tcf_csum_search,
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.size = sizeof(struct tcf_csum),
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