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net: sched: use rcu for action cookie update
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Implement functions to atomically update and free action cookie
using rcu mechanism.

Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Vlad Buslov authored and David S. Miller committed Jul 8, 2018
1 parent b233504 commit eec94fd
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Showing 3 changed files with 32 additions and 15 deletions.
2 changes: 1 addition & 1 deletion include/net/act_api.h
Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,7 @@ struct tc_action {
spinlock_t tcfa_lock;
struct gnet_stats_basic_cpu __percpu *cpu_bstats;
struct gnet_stats_queue __percpu *cpu_qstats;
struct tc_cookie *act_cookie;
struct tc_cookie __rcu *act_cookie;
struct tcf_chain *goto_chain;
};
#define tcf_index common.tcfa_index
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1 change: 1 addition & 0 deletions include/net/pkt_cls.h
Original file line number Diff line number Diff line change
Expand Up @@ -781,6 +781,7 @@ struct tc_mqprio_qopt_offload {
struct tc_cookie {
u8 *data;
u32 len;
struct rcu_head rcu;
};

struct tc_qopt_offload_stats {
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44 changes: 30 additions & 14 deletions net/sched/act_api.c
Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,24 @@ static void tcf_action_goto_chain_exec(const struct tc_action *a,
res->goto_tp = rcu_dereference_bh(chain->filter_chain);
}

static void tcf_free_cookie_rcu(struct rcu_head *p)
{
struct tc_cookie *cookie = container_of(p, struct tc_cookie, rcu);

kfree(cookie->data);
kfree(cookie);
}

static void tcf_set_action_cookie(struct tc_cookie __rcu **old_cookie,
struct tc_cookie *new_cookie)
{
struct tc_cookie *old;

old = xchg(old_cookie, new_cookie);
if (old)
call_rcu(&old->rcu, tcf_free_cookie_rcu);
}

/* XXX: For standalone actions, we don't need a RCU grace period either, because
* actions are always connected to filters and filters are already destroyed in
* RCU callbacks, so after a RCU grace period actions are already disconnected
Expand All @@ -65,10 +83,7 @@ static void free_tcf(struct tc_action *p)
free_percpu(p->cpu_bstats);
free_percpu(p->cpu_qstats);

if (p->act_cookie) {
kfree(p->act_cookie->data);
kfree(p->act_cookie);
}
tcf_set_action_cookie(&p->act_cookie, NULL);
if (p->goto_chain)
tcf_action_goto_chain_fini(p);

Expand Down Expand Up @@ -567,16 +582,22 @@ tcf_action_dump_1(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
int err = -EINVAL;
unsigned char *b = skb_tail_pointer(skb);
struct nlattr *nest;
struct tc_cookie *cookie;

if (nla_put_string(skb, TCA_KIND, a->ops->kind))
goto nla_put_failure;
if (tcf_action_copy_stats(skb, a, 0))
goto nla_put_failure;
if (a->act_cookie) {
if (nla_put(skb, TCA_ACT_COOKIE, a->act_cookie->len,
a->act_cookie->data))

rcu_read_lock();
cookie = rcu_dereference(a->act_cookie);
if (cookie) {
if (nla_put(skb, TCA_ACT_COOKIE, cookie->len, cookie->data)) {
rcu_read_unlock();
goto nla_put_failure;
}
}
rcu_read_unlock();

nest = nla_nest_start(skb, TCA_OPTIONS);
if (nest == NULL)
Expand Down Expand Up @@ -719,13 +740,8 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,
if (err < 0)
goto err_mod;

if (name == NULL && tb[TCA_ACT_COOKIE]) {
if (a->act_cookie) {
kfree(a->act_cookie->data);
kfree(a->act_cookie);
}
a->act_cookie = cookie;
}
if (!name && tb[TCA_ACT_COOKIE])
tcf_set_action_cookie(&a->act_cookie, cookie);

/* module count goes up only when brand new policy is created
* if it exists and is only bound to in a_o->init() then
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