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Message-ID: <CAM0EoMmQ75NMqdnC32d_vQ_5p23je4g8SVQvUy+sbu2y5JXCPA@mail.gmail.com>
Date: Tue, 2 Sep 2025 08:13:15 -0400
From: Jamal Hadi Salim <jhs@...atatu.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
Cong Wang <xiyou.wangcong@...il.com>, Jiri Pirko <jiri@...nulli.us>, netdev@...r.kernel.org,
eric.dumazet@...il.com
Subject: Re: [PATCH net-next] net_sched: add back BH safety to tcf_lock
On Tue, Sep 2, 2025 at 7:56 AM Jamal Hadi Salim <jhs@...atatu.com> wrote:
>
> On Mon, Sep 1, 2025 at 5:26 AM Eric Dumazet <edumazet@...gle.com> wrote:
> >
> > Jamal reported that we had to use BH safety after all,
> > because stats can be updated from BH handler.
> >
> > Fixes: 3133d5c15cb5 ("net_sched: remove BH blocking in eight actions")
> > Fixes: 53df77e78590 ("net_sched: act_skbmod: use RCU in tcf_skbmod_dump()")
> > Fixes: e97ae742972f ("net_sched: act_tunnel_key: use RCU in tunnel_key_dump()")
> > Fixes: 48b5e5dbdb23 ("net_sched: act_vlan: use RCU in tcf_vlan_dump()")
> > Reported-by: Jamal Hadi Salim <jhs@...atatu.com>
> > Closes: https://lore.kernel.org/netdev/CAM0EoMmhq66EtVqDEuNik8MVFZqkgxFbMu=fJtbNoYD7YXg4bA@mail.gmail.com/
> > Signed-off-by: Eric Dumazet <edumazet@...gle.com>
>
> Reviewed-by: Jamal Hadi Salim <jhs@...atatu.com>
>
> Eric - i dont think this will fix that lockdep splat i was referring
> to though, no?
>
Quick test reveals it was fixed ;->
cheers,
jamal
> cheers,
> jamal
> > ---
> > net/sched/act_connmark.c | 4 ++--
> > net/sched/act_csum.c | 4 ++--
> > net/sched/act_ct.c | 4 ++--
> > net/sched/act_ctinfo.c | 4 ++--
> > net/sched/act_mpls.c | 4 ++--
> > net/sched/act_nat.c | 4 ++--
> > net/sched/act_pedit.c | 4 ++--
> > net/sched/act_skbedit.c | 4 ++--
> > net/sched/act_skbmod.c | 4 ++--
> > net/sched/act_tunnel_key.c | 4 ++--
> > net/sched/act_vlan.c | 4 ++--
> > 11 files changed, 22 insertions(+), 22 deletions(-)
> >
> > diff --git a/net/sched/act_connmark.c b/net/sched/act_connmark.c
> > index bf2d6b6da042..3e89927d7116 100644
> > --- a/net/sched/act_connmark.c
> > +++ b/net/sched/act_connmark.c
> > @@ -169,10 +169,10 @@ static int tcf_connmark_init(struct net *net, struct nlattr *nla,
> >
> > nparms->action = parm->action;
> >
> > - spin_lock(&ci->tcf_lock);
> > + spin_lock_bh(&ci->tcf_lock);
> > goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
> > oparms = rcu_replace_pointer(ci->parms, nparms, lockdep_is_held(&ci->tcf_lock));
> > - spin_unlock(&ci->tcf_lock);
> > + spin_unlock_bh(&ci->tcf_lock);
> >
> > if (goto_ch)
> > tcf_chain_put_by_act(goto_ch);
> > diff --git a/net/sched/act_csum.c b/net/sched/act_csum.c
> > index 8bad91753615..0939e6b2ba4d 100644
> > --- a/net/sched/act_csum.c
> > +++ b/net/sched/act_csum.c
> > @@ -101,11 +101,11 @@ static int tcf_csum_init(struct net *net, struct nlattr *nla,
> > params_new->update_flags = parm->update_flags;
> > params_new->action = parm->action;
> >
> > - spin_lock(&p->tcf_lock);
> > + spin_lock_bh(&p->tcf_lock);
> > goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
> > params_new = rcu_replace_pointer(p->params, params_new,
> > lockdep_is_held(&p->tcf_lock));
> > - spin_unlock(&p->tcf_lock);
> > + spin_unlock_bh(&p->tcf_lock);
> >
> > if (goto_ch)
> > tcf_chain_put_by_act(goto_ch);
> > diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
> > index 6d2355e73b0f..6749a4a9a9cd 100644
> > --- a/net/sched/act_ct.c
> > +++ b/net/sched/act_ct.c
> > @@ -1410,11 +1410,11 @@ static int tcf_ct_init(struct net *net, struct nlattr *nla,
> > goto cleanup;
> >
> > params->action = parm->action;
> > - spin_lock(&c->tcf_lock);
> > + spin_lock_bh(&c->tcf_lock);
> > goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
> > params = rcu_replace_pointer(c->params, params,
> > lockdep_is_held(&c->tcf_lock));
> > - spin_unlock(&c->tcf_lock);
> > + spin_unlock_bh(&c->tcf_lock);
> >
> > if (goto_ch)
> > tcf_chain_put_by_act(goto_ch);
> > diff --git a/net/sched/act_ctinfo.c b/net/sched/act_ctinfo.c
> > index 6f79eed9a544..71efe04d00b5 100644
> > --- a/net/sched/act_ctinfo.c
> > +++ b/net/sched/act_ctinfo.c
> > @@ -258,11 +258,11 @@ static int tcf_ctinfo_init(struct net *net, struct nlattr *nla,
> >
> > cp_new->action = actparm->action;
> >
> > - spin_lock(&ci->tcf_lock);
> > + spin_lock_bh(&ci->tcf_lock);
> > goto_ch = tcf_action_set_ctrlact(*a, actparm->action, goto_ch);
> > cp_new = rcu_replace_pointer(ci->params, cp_new,
> > lockdep_is_held(&ci->tcf_lock));
> > - spin_unlock(&ci->tcf_lock);
> > + spin_unlock_bh(&ci->tcf_lock);
> >
> > if (goto_ch)
> > tcf_chain_put_by_act(goto_ch);
> > diff --git a/net/sched/act_mpls.c b/net/sched/act_mpls.c
> > index ed7bdaa23f0d..6654011dcd2b 100644
> > --- a/net/sched/act_mpls.c
> > +++ b/net/sched/act_mpls.c
> > @@ -296,10 +296,10 @@ static int tcf_mpls_init(struct net *net, struct nlattr *nla,
> > htons(ETH_P_MPLS_UC));
> > p->action = parm->action;
> >
> > - spin_lock(&m->tcf_lock);
> > + spin_lock_bh(&m->tcf_lock);
> > goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
> > p = rcu_replace_pointer(m->mpls_p, p, lockdep_is_held(&m->tcf_lock));
> > - spin_unlock(&m->tcf_lock);
> > + spin_unlock_bh(&m->tcf_lock);
> >
> > if (goto_ch)
> > tcf_chain_put_by_act(goto_ch);
> > diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
> > index 9cc2a1772cf8..26241d80ebe0 100644
> > --- a/net/sched/act_nat.c
> > +++ b/net/sched/act_nat.c
> > @@ -95,10 +95,10 @@ static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
> >
> > p = to_tcf_nat(*a);
> >
> > - spin_lock(&p->tcf_lock);
> > + spin_lock_bh(&p->tcf_lock);
> > goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
> > oparm = rcu_replace_pointer(p->parms, nparm, lockdep_is_held(&p->tcf_lock));
> > - spin_unlock(&p->tcf_lock);
> > + spin_unlock_bh(&p->tcf_lock);
> >
> > if (goto_ch)
> > tcf_chain_put_by_act(goto_ch);
> > diff --git a/net/sched/act_pedit.c b/net/sched/act_pedit.c
> > index 8fc8f577cb7a..4b65901397a8 100644
> > --- a/net/sched/act_pedit.c
> > +++ b/net/sched/act_pedit.c
> > @@ -280,10 +280,10 @@ static int tcf_pedit_init(struct net *net, struct nlattr *nla,
> >
> > p = to_pedit(*a);
> > nparms->action = parm->action;
> > - spin_lock(&p->tcf_lock);
> > + spin_lock_bh(&p->tcf_lock);
> > goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
> > oparms = rcu_replace_pointer(p->parms, nparms, 1);
> > - spin_unlock(&p->tcf_lock);
> > + spin_unlock_bh(&p->tcf_lock);
> >
> > if (oparms)
> > call_rcu(&oparms->rcu, tcf_pedit_cleanup_rcu);
> > diff --git a/net/sched/act_skbedit.c b/net/sched/act_skbedit.c
> > index aa6b1744de21..8c1d1554f657 100644
> > --- a/net/sched/act_skbedit.c
> > +++ b/net/sched/act_skbedit.c
> > @@ -261,11 +261,11 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla,
> > params_new->mask = *mask;
> >
> > params_new->action = parm->action;
> > - spin_lock(&d->tcf_lock);
> > + spin_lock_bh(&d->tcf_lock);
> > goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
> > params_new = rcu_replace_pointer(d->params, params_new,
> > lockdep_is_held(&d->tcf_lock));
> > - spin_unlock(&d->tcf_lock);
> > + spin_unlock_bh(&d->tcf_lock);
> > if (params_new)
> > kfree_rcu(params_new, rcu);
> > if (goto_ch)
> > diff --git a/net/sched/act_skbmod.c b/net/sched/act_skbmod.c
> > index fce625eafcb2..a9e0c1326e2a 100644
> > --- a/net/sched/act_skbmod.c
> > +++ b/net/sched/act_skbmod.c
> > @@ -194,7 +194,7 @@ static int tcf_skbmod_init(struct net *net, struct nlattr *nla,
> > p->flags = lflags;
> > p->action = parm->action;
> > if (ovr)
> > - spin_lock(&d->tcf_lock);
> > + spin_lock_bh(&d->tcf_lock);
> > /* Protected by tcf_lock if overwriting existing action. */
> > goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
> > p_old = rcu_dereference_protected(d->skbmod_p, 1);
> > @@ -208,7 +208,7 @@ static int tcf_skbmod_init(struct net *net, struct nlattr *nla,
> >
> > rcu_assign_pointer(d->skbmod_p, p);
> > if (ovr)
> > - spin_unlock(&d->tcf_lock);
> > + spin_unlock_bh(&d->tcf_lock);
> >
> > if (p_old)
> > kfree_rcu(p_old, rcu);
> > diff --git a/net/sched/act_tunnel_key.c b/net/sched/act_tunnel_key.c
> > index e1c8b48c217c..876b30c5709e 100644
> > --- a/net/sched/act_tunnel_key.c
> > +++ b/net/sched/act_tunnel_key.c
> > @@ -531,11 +531,11 @@ static int tunnel_key_init(struct net *net, struct nlattr *nla,
> > params_new->tcft_enc_metadata = metadata;
> >
> > params_new->action = parm->action;
> > - spin_lock(&t->tcf_lock);
> > + spin_lock_bh(&t->tcf_lock);
> > goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
> > params_new = rcu_replace_pointer(t->params, params_new,
> > lockdep_is_held(&t->tcf_lock));
> > - spin_unlock(&t->tcf_lock);
> > + spin_unlock_bh(&t->tcf_lock);
> > tunnel_key_release_params(params_new);
> > if (goto_ch)
> > tcf_chain_put_by_act(goto_ch);
> > diff --git a/net/sched/act_vlan.c b/net/sched/act_vlan.c
> > index b46f980f3b2a..a74621797d69 100644
> > --- a/net/sched/act_vlan.c
> > +++ b/net/sched/act_vlan.c
> > @@ -253,10 +253,10 @@ static int tcf_vlan_init(struct net *net, struct nlattr *nla,
> > }
> >
> > p->action = parm->action;
> > - spin_lock(&v->tcf_lock);
> > + spin_lock_bh(&v->tcf_lock);
> > goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
> > p = rcu_replace_pointer(v->vlan_p, p, lockdep_is_held(&v->tcf_lock));
> > - spin_unlock(&v->tcf_lock);
> > + spin_unlock_bh(&v->tcf_lock);
> >
> > if (goto_ch)
> > tcf_chain_put_by_act(goto_ch);
> > --
> > 2.51.0.318.gd7df087d1a-goog
> >
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