From b6a2b971c0b00253197682fbdf1c55fc0e2610a4 Mon Sep 17 00:00:00 2001 From: Vlad Buslov Date: Fri, 10 Aug 2018 20:51:42 +0300 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- net/sched/act_csum.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/net/sched/act_csum.c b/net/sched/act_csum.c index 648a3a35b720..f01c59ba6d12 100644 --- a/net/sched/act_csum.c +++ b/net/sched/act_csum.c @@ -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); + params_new->update_flags = parm->update_flags; + spin_lock(&p->tcf_lock); 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); + 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; } -- 2.34.1