From: WANG Cong xiyou.wangcong@gmail.com
[ Upstream commit 74030603dfd9f76c0f279f19f1dd1ee3028fee7a ]
Laura reported a sleep-in-atomic kernel warning inside tcf_act_police_init() which calls gen_replace_estimator() with spinlock protection.
It is not necessary in this case, we already have RTNL lock here so it is enough to protect concurrent writers. For the reader, i.e. tcf_act_police(), it needs to make decision based on this rate estimator, in the worst case we drop more/less packets than necessary while changing the rate in parallel, it is still acceptable.
Reported-by: Laura Abbott labbott@redhat.com Reported-by: Nick Huber nicholashuber@gmail.com Cc: Jamal Hadi Salim jhs@mojatatu.com Signed-off-by: Cong Wang xiyou.wangcong@gmail.com Acked-by: Jamal Hadi Salim jhs@mojatatu.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- net/sched/act_police.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/net/sched/act_police.c b/net/sched/act_police.c index d1bd248fe146..ca30796290aa 100644 --- a/net/sched/act_police.c +++ b/net/sched/act_police.c @@ -132,22 +132,22 @@ static int tcf_act_police_init(struct net *net, struct nlattr *nla, } }
- spin_lock_bh(&police->tcf_lock); if (est) { err = gen_replace_estimator(&police->tcf_bstats, NULL, &police->tcf_rate_est, &police->tcf_lock, NULL, est); if (err) - goto failure_unlock; + goto failure; } else if (tb[TCA_POLICE_AVRATE] && (ret == ACT_P_CREATED || !gen_estimator_active(&police->tcf_bstats, &police->tcf_rate_est))) { err = -EINVAL; - goto failure_unlock; + goto failure; }
+ spin_lock_bh(&police->tcf_lock); /* No failure allowed after this point */ police->tcfp_mtu = parm->mtu; if (police->tcfp_mtu == 0) { @@ -193,8 +193,6 @@ static int tcf_act_police_init(struct net *net, struct nlattr *nla,
return ret;
-failure_unlock: - spin_unlock_bh(&police->tcf_lock); failure: qdisc_put_rtab(P_tab); qdisc_put_rtab(R_tab);