linux/net/sched/cls_cgroup.c
Patrick McHardy 47a1a1d4be pkt_sched: remove unnecessary xchg() in packet classifiers
The use of xchg() hasn't been necessary since 2.2.something when proper
locking was added to packet schedulers. In the case of classifiers they
mostly weren't even necessary before that since they're mainly used
to assign a NULL pointer to the filter root in the ->destroy path;
the root is destroyed immediately after that.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-20 04:14:28 -08:00

289 lines
6.3 KiB
C

/*
* net/sched/cls_cgroup.c Control Group Classifier
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Authors: Thomas Graf <tgraf@suug.ch>
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/cgroup.h>
#include <net/rtnetlink.h>
#include <net/pkt_cls.h>
struct cgroup_cls_state
{
struct cgroup_subsys_state css;
u32 classid;
};
static inline struct cgroup_cls_state *net_cls_state(struct cgroup *cgrp)
{
return (struct cgroup_cls_state *)
cgroup_subsys_state(cgrp, net_cls_subsys_id);
}
static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss,
struct cgroup *cgrp)
{
struct cgroup_cls_state *cs;
if (!(cs = kzalloc(sizeof(*cs), GFP_KERNEL)))
return ERR_PTR(-ENOMEM);
if (cgrp->parent)
cs->classid = net_cls_state(cgrp->parent)->classid;
return &cs->css;
}
static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
{
kfree(ss);
}
static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
{
return net_cls_state(cgrp)->classid;
}
static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
{
if (!cgroup_lock_live_group(cgrp))
return -ENODEV;
net_cls_state(cgrp)->classid = (u32) value;
cgroup_unlock();
return 0;
}
static struct cftype ss_files[] = {
{
.name = "classid",
.read_u64 = read_classid,
.write_u64 = write_classid,
},
};
static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
{
return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
}
struct cgroup_subsys net_cls_subsys = {
.name = "net_cls",
.create = cgrp_create,
.destroy = cgrp_destroy,
.populate = cgrp_populate,
.subsys_id = net_cls_subsys_id,
};
struct cls_cgroup_head
{
u32 handle;
struct tcf_exts exts;
struct tcf_ematch_tree ematches;
};
static int cls_cgroup_classify(struct sk_buff *skb, struct tcf_proto *tp,
struct tcf_result *res)
{
struct cls_cgroup_head *head = tp->root;
struct cgroup_cls_state *cs;
int ret = 0;
/*
* Due to the nature of the classifier it is required to ignore all
* packets originating from softirq context as accessing `current'
* would lead to false results.
*
* This test assumes that all callers of dev_queue_xmit() explicitely
* disable bh. Knowing this, it is possible to detect softirq based
* calls by looking at the number of nested bh disable calls because
* softirqs always disables bh.
*/
if (softirq_count() != SOFTIRQ_OFFSET)
return -1;
rcu_read_lock();
cs = (struct cgroup_cls_state *) task_subsys_state(current,
net_cls_subsys_id);
if (cs->classid && tcf_em_tree_match(skb, &head->ematches, NULL)) {
res->classid = cs->classid;
res->class = 0;
ret = tcf_exts_exec(skb, &head->exts, res);
} else
ret = -1;
rcu_read_unlock();
return ret;
}
static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
{
return 0UL;
}
static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
{
}
static int cls_cgroup_init(struct tcf_proto *tp)
{
return 0;
}
static const struct tcf_ext_map cgroup_ext_map = {
.action = TCA_CGROUP_ACT,
.police = TCA_CGROUP_POLICE,
};
static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
[TCA_CGROUP_EMATCHES] = { .type = NLA_NESTED },
};
static int cls_cgroup_change(struct tcf_proto *tp, unsigned long base,
u32 handle, struct nlattr **tca,
unsigned long *arg)
{
struct nlattr *tb[TCA_CGROUP_MAX+1];
struct cls_cgroup_head *head = tp->root;
struct tcf_ematch_tree t;
struct tcf_exts e;
int err;
if (head == NULL) {
if (!handle)
return -EINVAL;
head = kzalloc(sizeof(*head), GFP_KERNEL);
if (head == NULL)
return -ENOBUFS;
head->handle = handle;
tcf_tree_lock(tp);
tp->root = head;
tcf_tree_unlock(tp);
}
if (handle != head->handle)
return -ENOENT;
err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
cgroup_policy);
if (err < 0)
return err;
err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
if (err < 0)
return err;
err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
if (err < 0)
return err;
tcf_exts_change(tp, &head->exts, &e);
tcf_em_tree_change(tp, &head->ematches, &t);
return 0;
}
static void cls_cgroup_destroy(struct tcf_proto *tp)
{
struct cls_cgroup_head *head = tp->root;
if (head) {
tcf_exts_destroy(tp, &head->exts);
tcf_em_tree_destroy(tp, &head->ematches);
kfree(head);
}
}
static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
{
return -EOPNOTSUPP;
}
static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
{
struct cls_cgroup_head *head = tp->root;
if (arg->count < arg->skip)
goto skip;
if (arg->fn(tp, (unsigned long) head, arg) < 0) {
arg->stop = 1;
return;
}
skip:
arg->count++;
}
static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
struct sk_buff *skb, struct tcmsg *t)
{
struct cls_cgroup_head *head = tp->root;
unsigned char *b = skb_tail_pointer(skb);
struct nlattr *nest;
t->tcm_handle = head->handle;
nest = nla_nest_start(skb, TCA_OPTIONS);
if (nest == NULL)
goto nla_put_failure;
if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
goto nla_put_failure;
nla_nest_end(skb, nest);
if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
goto nla_put_failure;
return skb->len;
nla_put_failure:
nlmsg_trim(skb, b);
return -1;
}
static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
.kind = "cgroup",
.init = cls_cgroup_init,
.change = cls_cgroup_change,
.classify = cls_cgroup_classify,
.destroy = cls_cgroup_destroy,
.get = cls_cgroup_get,
.put = cls_cgroup_put,
.delete = cls_cgroup_delete,
.walk = cls_cgroup_walk,
.dump = cls_cgroup_dump,
.owner = THIS_MODULE,
};
static int __init init_cgroup_cls(void)
{
return register_tcf_proto_ops(&cls_cgroup_ops);
}
static void __exit exit_cgroup_cls(void)
{
unregister_tcf_proto_ops(&cls_cgroup_ops);
}
module_init(init_cgroup_cls);
module_exit(exit_cgroup_cls);
MODULE_LICENSE("GPL");