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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>
This commit is contained in:
WANG Cong 2017-06-13 13:36:24 -07:00 committed by David S. Miller
parent 20a3d5bf5e
commit 74030603df
1 changed files with 3 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
net/sched/act_police.c
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@ -132,21 +132,21 @@ static int tcf_act_police_init(struct net *net, struct nlattr *nla,
} }
} }
spin_lock_bh(&police->tcf_lock);
if (est) { if (est) {
err = gen_replace_estimator(&police->tcf_bstats, NULL, err = gen_replace_estimator(&police->tcf_bstats, NULL,
&police->tcf_rate_est, &police->tcf_rate_est,
&police->tcf_lock, &police->tcf_lock,
NULL, est); NULL, est);
if (err) if (err)
goto failure_unlock; goto failure;
} else if (tb[TCA_POLICE_AVRATE] && } else if (tb[TCA_POLICE_AVRATE] &&
(ret == ACT_P_CREATED || (ret == ACT_P_CREATED ||
!gen_estimator_active(&police->tcf_rate_est))) { !gen_estimator_active(&police->tcf_rate_est))) {
err = -EINVAL; err = -EINVAL;
goto failure_unlock; goto failure;
} }
spin_lock_bh(&police->tcf_lock);
/* No failure allowed after this point */ /* No failure allowed after this point */
police->tcfp_mtu = parm->mtu; police->tcfp_mtu = parm->mtu;
if (police->tcfp_mtu == 0) { if (police->tcfp_mtu == 0) {
@ -192,8 +192,6 @@ static int tcf_act_police_init(struct net *net, struct nlattr *nla,
return ret; return ret;
failure_unlock:
spin_unlock_bh(&police->tcf_lock);
failure: failure:
qdisc_put_rtab(P_tab); qdisc_put_rtab(P_tab);
qdisc_put_rtab(R_tab); qdisc_put_rtab(R_tab);