From 74030603dfd9f76c0f279f19f1dd1ee3028fee7a Mon Sep 17 00:00:00 2001
From: WANG Cong <xiyou.wangcong@gmail.com>
Date: Tue, 13 Jun 2017 13:36:24 -0700
Subject: [PATCH] net_sched: move tcf_lock down after gen_replace_estimator()
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>
---
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 f42008b293112..b062bc80c7cb1 100644
--- a/net/sched/act_police.c
+++ b/net/sched/act_police.c
@@ -132,21 +132,21 @@ 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_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) {
@@ -192,8 +192,6 @@ 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);
--
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