pkt_sched: gen_kill_estimator() rcu fixes
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 5d944c640b4
(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>
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 972378f..23b25f8 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -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 @@
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;
}
}
diff --git a/net/sched/act_police.c b/net/sched/act_police.c
index 654f73d..537a487 100644
--- a/net/sched/act_police.c
+++ b/net/sched/act_police.c
@@ -97,6 +97,11 @@
goto done;
}
+static void tcf_police_free_rcu(struct rcu_head *head)
+{
+ kfree(container_of(head, struct tcf_police, tcf_rcu));
+}
+
static void tcf_police_destroy(struct tcf_police *p)
{
unsigned int h = tcf_hash(p->tcf_index, POL_TAB_MASK);
@@ -113,7 +118,11 @@
qdisc_put_rtab(p->tcfp_R_tab);
if (p->tcfp_P_tab)
qdisc_put_rtab(p->tcfp_P_tab);
- kfree(p);
+ /*
+ * gen_estimator est_timer() might access p->tcf_lock
+ * or bstats, wait a RCU grace period before freeing p
+ */
+ call_rcu(&p->tcf_rcu, tcf_police_free_rcu);
return;
}
}
@@ -397,6 +406,7 @@
police_cleanup_module(void)
{
tcf_unregister_action(&act_police_ops);
+ rcu_barrier(); /* Wait for completion of call_rcu()'s (tcf_police_free_rcu) */
}
module_init(police_init_module);