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pkt_sched: gen_kill_estimator() rcu fixes

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gen_kill_estimator() API is incomplete or not well documented, since
caller should make sure an RCU grace period is respected before
freeing stats_lock.

This was partially addressed in commit 5d944c640b
(gen_estimator: deadlock fix), but same problem exist for all
gen_kill_estimator() users, if lock they use is not already RCU
protected.

A code review shows xt_RATEEST.c, act_api.c, act_police.c have this
problem. Other are ok because they use qdisc lock, already RCU
protected.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2010-06-09 02:09:23 +00:00
committed by David S. Miller
parent cbd6890c59
commit c7de2cf053
6 changed files with 36 additions and 3 deletions
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11
net/sched/act_api.c
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@@ -26,6 +26,11 @@
#include <net/act_api.h>
#include <net/netlink.h>
static void tcf_common_free_rcu(struct rcu_head *head)
{
kfree(container_of(head, struct tcf_common, tcfc_rcu));
}
void tcf_hash_destroy(struct tcf_common *p, struct tcf_hashinfo *hinfo)
{
unsigned int h = tcf_hash(p->tcfc_index, hinfo->hmask);
@@ -38,7 +43,11 @@ void tcf_hash_destroy(struct tcf_common *p, struct tcf_hashinfo *hinfo)
write_unlock_bh(hinfo->lock);
gen_kill_estimator(&p->tcfc_bstats,
&p->tcfc_rate_est);
kfree(p);
/*
* gen_estimator est_timer() might access p->tcfc_lock
* or bstats, wait a RCU grace period before freeing p
*/
call_rcu(&p->tcfc_rcu, tcf_common_free_rcu);
return;
}
}