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net: sched: act_csum: remove dependency on rtnl lock 

Use tcf lock to protect csum action struct private data from concurrent
modification in init and dump. Use rcu swap operation to reassign params
pointer under protection of tcf lock. (old params value is not used by
init, so there is no need of standalone rcu dereference step)

Remove rtnl assertion that is no longer necessary.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vlad Buslov 2018-08-10 20:51:42 +03:00 committed by David S. Miller
parent 2142236b45
commit b6a2b971c0
1 changed files with 16 additions and 10 deletions
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26
net/sched/act_csum.c
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@ -50,7 +50,7 @@ static int tcf_csum_init(struct net *net, struct nlattr *nla,
struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, csum_net_id);
struct tcf_csum_params *params_old, *params_new;
struct tcf_csum_params *params_new;
struct nlattr *tb[TCA_CSUM_MAX + 1];
struct tc_csum *parm;
struct tcf_csum *p;
@ -88,20 +88,22 @@ static int tcf_csum_init(struct net *net, struct nlattr *nla,
}
p = to_tcf_csum(*a);
ASSERT_RTNL();
params_new = kzalloc(sizeof(*params_new), GFP_KERNEL);
if (unlikely(!params_new)) {
tcf_idr_release(*a, bind);
return -ENOMEM;
}
params_old = rtnl_dereference(p->params);
p->tcf_action = parm->action;
params_new->update_flags = parm->update_flags;
rcu_assign_pointer(p->params, params_new);
if (params_old)
kfree_rcu(params_old, rcu);
spin_lock(&p->tcf_lock);
p->tcf_action = parm->action;
rcu_swap_protected(p->params, params_new,
lockdep_is_held(&p->tcf_lock));
spin_unlock(&p->tcf_lock);
if (params_new)
kfree_rcu(params_new, rcu);
if (ret == ACT_P_CREATED)
tcf_idr_insert(tn, *a);
@ -599,11 +601,13 @@ static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind,
.index = p->tcf_index,
.refcnt = refcount_read(&p->tcf_refcnt) - ref,
.bindcnt = atomic_read(&p->tcf_bindcnt) - bind,
.action = p->tcf_action,
};
struct tcf_t t;
params = rtnl_dereference(p->params);
spin_lock(&p->tcf_lock);
params = rcu_dereference_protected(p->params,
lockdep_is_held(&p->tcf_lock));
opt.action = p->tcf_action;
opt.update_flags = params->update_flags;
if (nla_put(skb, TCA_CSUM_PARMS, sizeof(opt), &opt))
@ -612,10 +616,12 @@ static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind,
tcf_tm_dump(&t, &p->tcf_tm);
if (nla_put_64bit(skb, TCA_CSUM_TM, sizeof(t), &t, TCA_CSUM_PAD))
goto nla_put_failure;
spin_unlock(&p->tcf_lock);
return skb->len;
nla_put_failure:
spin_unlock(&p->tcf_lock);
nlmsg_trim(skb, b);
return -1;
}