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linux-stable/include/net/act_api.h
Paolo Abeni 7fd4b288ea tc/act: remove unneeded RCU lock in action callback 
Each lockless action currently does its own RCU locking in ->act().
This allows using plain RCU accessor, even if the context
is really RCU BH.

This change drops the per action RCU lock, replace the accessors
with the _bh variant, cleans up a bit the surrounding code and
documents the RCU status in the relevant header.
No functional nor performance change is intended.

The goal of this patch is clarifying that the RCU critical section
used by the tc actions extends up to the classifier's caller.

v1 -> v2:
 - preserve rcu lock in act_bpf: it's needed by eBPF helpers,
   as pointed out by Daniel

v3 -> v4:
 - fixed some typos in the commit message (JiriP)

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-30 09:31:13 -07:00

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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __NET_ACT_API_H
#define __NET_ACT_API_H
/*
* Public action API for classifiers/qdiscs
*/
#include <linux/refcount.h>
#include <net/sch_generic.h>
#include <net/pkt_sched.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
struct tcf_idrinfo {
spinlock_t lock;
struct idr action_idr;
};
struct tc_action_ops;
struct tc_action {
const struct tc_action_ops *ops;
__u32 type; /* for backward compat(TCA_OLD_COMPAT) */
__u32 order;
struct list_head list;
struct tcf_idrinfo *idrinfo;
u32 tcfa_index;
refcount_t tcfa_refcnt;
atomic_t tcfa_bindcnt;
u32 tcfa_capab;
int tcfa_action;
struct tcf_t tcfa_tm;
struct gnet_stats_basic_packed tcfa_bstats;
struct gnet_stats_queue tcfa_qstats;
struct net_rate_estimator __rcu *tcfa_rate_est;
spinlock_t tcfa_lock;
struct gnet_stats_basic_cpu __percpu *cpu_bstats;
struct gnet_stats_queue __percpu *cpu_qstats;
struct tc_cookie __rcu *act_cookie;
struct tcf_chain *goto_chain;
};
#define tcf_index common.tcfa_index
#define tcf_refcnt common.tcfa_refcnt
#define tcf_bindcnt common.tcfa_bindcnt
#define tcf_capab common.tcfa_capab
#define tcf_action common.tcfa_action
#define tcf_tm common.tcfa_tm
#define tcf_bstats common.tcfa_bstats
#define tcf_qstats common.tcfa_qstats
#define tcf_rate_est common.tcfa_rate_est
#define tcf_lock common.tcfa_lock
/* Update lastuse only if needed, to avoid dirtying a cache line.
* We use a temp variable to avoid fetching jiffies twice.
*/
static inline void tcf_lastuse_update(struct tcf_t *tm)
{
unsigned long now = jiffies;
if (tm->lastuse != now)
tm->lastuse = now;
if (unlikely(!tm->firstuse))
tm->firstuse = now;
}
static inline void tcf_tm_dump(struct tcf_t *dtm, const struct tcf_t *stm)
{
dtm->install = jiffies_to_clock_t(jiffies - stm->install);
dtm->lastuse = jiffies_to_clock_t(jiffies - stm->lastuse);
dtm->firstuse = jiffies_to_clock_t(jiffies - stm->firstuse);
dtm->expires = jiffies_to_clock_t(stm->expires);
}
#ifdef CONFIG_NET_CLS_ACT
#define ACT_P_CREATED 1
#define ACT_P_DELETED 1
struct tc_action_ops {
struct list_head head;
char kind[IFNAMSIZ];
__u32 type; /* TBD to match kind */
size_t size;
struct module *owner;
int (*act)(struct sk_buff *, const struct tc_action *,
struct tcf_result *); /* called under RCU BH lock*/
int (*dump)(struct sk_buff *, struct tc_action *, int, int);
void (*cleanup)(struct tc_action *);
int (*lookup)(struct net *net, struct tc_action **a, u32 index,
struct netlink_ext_ack *extack);
int (*init)(struct net *net, struct nlattr *nla,
struct nlattr *est, struct tc_action **act, int ovr,
int bind, bool rtnl_held,
struct netlink_ext_ack *extack);
int (*walk)(struct net *, struct sk_buff *,
struct netlink_callback *, int,
const struct tc_action_ops *,
struct netlink_ext_ack *);
void (*stats_update)(struct tc_action *, u64, u32, u64);
size_t (*get_fill_size)(const struct tc_action *act);
struct net_device *(*get_dev)(const struct tc_action *a);
int (*delete)(struct net *net, u32 index);
};
struct tc_action_net {
struct tcf_idrinfo *idrinfo;
const struct tc_action_ops *ops;
};
static inline
int tc_action_net_init(struct tc_action_net *tn,
const struct tc_action_ops *ops)
{
int err = 0;
tn->idrinfo = kmalloc(sizeof(*tn->idrinfo), GFP_KERNEL);
if (!tn->idrinfo)
return -ENOMEM;
tn->ops = ops;
spin_lock_init(&tn->idrinfo->lock);
idr_init(&tn->idrinfo->action_idr);
return err;
}
void tcf_idrinfo_destroy(const struct tc_action_ops *ops,
struct tcf_idrinfo *idrinfo);
static inline void tc_action_net_exit(struct list_head *net_list,
unsigned int id)
{
struct net *net;
rtnl_lock();
list_for_each_entry(net, net_list, exit_list) {
struct tc_action_net *tn = net_generic(net, id);
tcf_idrinfo_destroy(tn->ops, tn->idrinfo);
kfree(tn->idrinfo);
}
rtnl_unlock();
}
int tcf_generic_walker(struct tc_action_net *tn, struct sk_buff *skb,
struct netlink_callback *cb, int type,
const struct tc_action_ops *ops,
struct netlink_ext_ack *extack);
int tcf_idr_search(struct tc_action_net *tn, struct tc_action **a, u32 index);
bool tcf_idr_check(struct tc_action_net *tn, u32 index, struct tc_action **a,
int bind);
int tcf_idr_create(struct tc_action_net *tn, u32 index, struct nlattr *est,
struct tc_action **a, const struct tc_action_ops *ops,
int bind, bool cpustats);
void tcf_idr_insert(struct tc_action_net *tn, struct tc_action *a);
void tcf_idr_cleanup(struct tc_action_net *tn, u32 index);
int tcf_idr_check_alloc(struct tc_action_net *tn, u32 *index,
struct tc_action **a, int bind);
int tcf_idr_delete_index(struct tc_action_net *tn, u32 index);
int __tcf_idr_release(struct tc_action *a, bool bind, bool strict);
static inline int tcf_idr_release(struct tc_action *a, bool bind)
{
return __tcf_idr_release(a, bind, false);
}
int tcf_register_action(struct tc_action_ops *a, struct pernet_operations *ops);
int tcf_unregister_action(struct tc_action_ops *a,
struct pernet_operations *ops);
int tcf_action_destroy(struct tc_action *actions[], int bind);
int tcf_action_exec(struct sk_buff *skb, struct tc_action **actions,
int nr_actions, struct tcf_result *res);
int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla,
struct nlattr *est, char *name, int ovr, int bind,
struct tc_action *actions[], size_t *attr_size,
bool rtnl_held, struct netlink_ext_ack *extack);
struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,
struct nlattr *nla, struct nlattr *est,
char *name, int ovr, int bind,
bool rtnl_held,
struct netlink_ext_ack *extack);
int tcf_action_dump(struct sk_buff *skb, struct tc_action *actions[], int bind,
int ref);
int tcf_action_dump_old(struct sk_buff *skb, struct tc_action *a, int, int);
int tcf_action_dump_1(struct sk_buff *skb, struct tc_action *a, int, int);
int tcf_action_copy_stats(struct sk_buff *, struct tc_action *, int);
#endif /* CONFIG_NET_CLS_ACT */
static inline void tcf_action_stats_update(struct tc_action *a, u64 bytes,
u64 packets, u64 lastuse)
{
#ifdef CONFIG_NET_CLS_ACT
if (!a->ops->stats_update)
return;
a->ops->stats_update(a, bytes, packets, lastuse);
#endif
}
#ifdef CONFIG_NET_CLS_ACT
int tc_setup_cb_egdev_register(const struct net_device *dev,
tc_setup_cb_t *cb, void *cb_priv);
void tc_setup_cb_egdev_unregister(const struct net_device *dev,
tc_setup_cb_t *cb, void *cb_priv);
int tc_setup_cb_egdev_call(const struct net_device *dev,
enum tc_setup_type type, void *type_data,
bool err_stop);
#else
static inline
int tc_setup_cb_egdev_register(const struct net_device *dev,
tc_setup_cb_t *cb, void *cb_priv)
{
return 0;
}
static inline
void tc_setup_cb_egdev_unregister(const struct net_device *dev,
tc_setup_cb_t *cb, void *cb_priv)
{
}
static inline
int tc_setup_cb_egdev_call(const struct net_device *dev,
enum tc_setup_type type, void *type_data,
bool err_stop)
{
return 0;
}
#endif
#endif
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